. . . See also: Planetary Space News.)
. . . Note, too, that there's 8 times more H floating free than there is in stars.
. . This is the clearest explanation I've found on dark energy & the expansion of the universe (eXit to return).
* My (prob'ly wacky) idea: the so-called anti-gravity now
known to exist between galaxies --pushing them apart &
speeding up the expansion-- must also push IN on the edges of all widely-separated galaxies. This would make them more compact & would rotate faster, making it seem like they're heavier than they are. i.e. they don't rotate fast because there's a heavy center --BH or not, but because it's Anti-Grav "pushing", rather than gravity "pulling". I wonder if this has been inserted into their calculations.
Neutron star gravity: 300,000 times that at Earth.
If the sun collapsed into a singularity, its event horizon
would measure approximately 3 km across. If Earth followed
suit, its event horizon would only measure 1 centimeter.
For perhaps its first million years, the Universe was small and dense enough that sound waves could travel through it [!] --so efficiently, in fact, that they moved at about half the speed of light! 500,000 X as fast. & the Universe was so small then, sound cuda gotten across quickly.
The Milky Way in its entirety spans more than 100,000 light-years.
.
Feb 2003: a joint NASA–Princeton University satellite, the Wilkinson Microwave Anisotropic Probe, produced a high-resolution map that captured the oldest light in the universe. This ancient light, called the cosmic microwave background, is the cooled remnant of the Big Bang. This has accurately determined the age of the universe -—with just a 1% margin of error: 13.7 billion years old.
. . The Earth is 4.6 billion years old.
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NEWS:
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Dec 18, 08: The origin of life and the habitability of worlds other than Earth are two of the biggest mysteries facing science today. Much research has been dedicated to these topics, but there is still a lack of definite answers.
. . Jan Hendrik Bredehöft from the UK's Open University has been considering habitability on other worlds. "I'm one of those guys who takes a piece of meteorite, grinds it up and finds out what the organic chemistry is in there", said Bredehöft.
. . Based on these types of studies, he has come to believe that habitable worlds can be split into four categories, each with varying likelihoods of being home to extraterrestrial organisms. This has great potential for assisting the search for life in the universe.
. . His four groups of habitable worlds are: Earth-like, Mars-Like, Europa-like and water-worlds.
. . The second class of planets are those that were once much like Earth, such as Mars and Venus. "For some reason these planets left the classical habitable zone", said Bredehöft. "Mars became too dry, there's very little water left, at least not liquid water. Venus became just so enormously hot due to the greenhouse effect."
. . Still, Bredehöft believes there is some chance for life to exist on this type of world. He reasons that organisms could have developed when the planet was more hospitable, and this life could maintain a grip even through the hard times. "Once life has established itself it is really hard to kill off."
. . Bodies that possess liquid water, but under an ice layer rather than on the surface, make up the third class of worlds.
. . The traditional view of habitable zones thinks of a local star as being the prime energy source. But on icy worlds like Europa, other factors come into play, such as the gravitational pull of another planet. Worlds with liquid water hidden beneath icy layers could potentially be inhabited by simple organisms despite being far from the conventional habitable zone, so long as energy is provided in some other way.
. . The fourth kind of habitable planets are made almost entirely of water. These hypothetical worlds would be Mercury to Earth-sized and would feature extensive oceans. Unlike oceans on Earth, the water on these types of planets would not be in contact with silicates or other rocks.
. . One theory for life's origin on Earth says organic material collected in shallow pools and then became concentrated by clinging to the surface of rocks. Eventually, this early life spread into the wider ocean. Another theory for life's origin is that the necessary chemistry occurred at hydrothermal volcanic vents. On water worlds, however, these scenarios are impossible. Therefore, Bredehöft thinks life is not likely to originate on such planets.
. . Bredehöft said the best bet to find extraterrestrial ecosystems is to hunt for Earth-like planets, after all. So in Bredehöft's carefully considered opinion, what kind of organisms are we most likely to find? "Probably something slimy."
Dec 17, 08: Astronomers detected water in a galaxy 11 billion light-years from earth, the farthest it has ever been found.
Dec 16, 08: No matter the heft of the black hole, its surrounding material took the shape of a doughnut with a black hole at its center.
Dec 16, 08: Billions of years ago, the universe was crowded with tight-knit clusters of galaxies. Then, a party crasher got the upper hand. This mysterious force now called dark energy has since been expanding the universe at an increasing pace. Some "force" is causing galaxies to fly away from one another, operating like antigravity.
. . New measurements of this accelerating expansion, which drives galaxies away from one another on large scales but so far shows no effects on small scales (such as within a galaxy), provide details about the nature of the unseen and unknown dark energy that is at work.
. . The results, announced today at a news conference organized by NASA, reveal a decrease in the mass of galaxy clusters in more recent times, which would be a consequence of this hastening and ripping force that some think could eventually tear apart even star systems, planets and eventually the very molecules we're made of.
. . If dark energy is indeed some kind of repulsive force that is linked with "nothing", and the density of dark energy stays the same over time, astrophysicists say the expansion of the universe will continue to speed up. It seems to have another effect: It prevents the biggest clusters of galaxies from getting too fat.
. . Dark energy was discovered in 1998 by two teams of astronomers, who measured light coming from exploding stars called Type IA supernovae, known as "standard candles" for their consistent brightness. The striking result was that distant supernovae were dimmer (farther away) than they would be in a universe that was slowing down. The result suggested the expansion of the universe was accelerating. And the teams proposed something called dark energy could be driving this acceleration. This acceleration, it is thought, began about 5 billion years ago.
Dec 15, 08: A pair of failed stars takes the record of being the dimmest bulbs ever detected, astronomers find. Each of the substellar objects, called brown dwarfs, is one million times fainter than the sun in total light on the electromagnetic spectrum, and at least one billion times fainter in visible light alone.
. . A brown dwarf is a compact ball of gas floating freely in space that's too cool and lightweight to generate the thermonuclear fusion that powers real stars, but too warm and massive to be considered a planet.
. . Until now, astronomers thought this dim duo was a single, faint brown dwarf. Past research has shown the object is the fifth closest known brown dwarf to us, 17 light-years away.
. . The data showed that what was still thought to be a single object had a warm atmospheric temp of 293 to 360 degrees C. While this is hundreds of degrees hotter than Jupiter, it's still downright cold as far as stars go.
. . They also estimated the brightness, which they found to be twice what would be expected for a brown dwarf with its particular temperature. The solution: The object must have twice the surface area. So each body shines only half as bright, and each has a mass of 30 to 40 times that of Jupiter.
Dec 13, 08: A hot and aging star exhibits something never seen before. Sounds like a lurid Hollywood tale, but the discovery is a cosmic one. Astronomers have found a white dwarf star with a surface temperature of 200,000 C. It's so hot that "its photosphere exhibits emission lines in the ultraviolet spectrum, a phenomenon that has never been seen before", the researchers said.
. . The white dwarf, named KPD 0005+5106, is among the hottest stars ever known. Catching one so hot is a low-probability affair, because they don't stay that hot for long.
. . Our sun is about 10,000 degrees F. Scientists have previously theorized that surfaces of the hottest stars could be up to 120,000 degrees C For short times, when stars much more massive than the sun explode, the inside temperature could reach as high as 10 billion degrees F.
Dec 10, 08: A new giant virtual telescope is the most powerful tool scientists have ever had to study the universe in a part of the electromagnetic spectrum called long wavelength submillimeter light. Mauna Kea's lofty location at 4,000 meters is perfect.
. . The Extended Submillimeter Array (eSMA) was created by combining three telescopes in Hawaii using computer software. By routing them together in a process called interferometry, the combined telescopes have the virtual resolution of one huge telescope the size of the distance between them. In this case, the virtual telescope has a diameter of 782 meters.
. . The SubMillimeter Array, which contains eight dishes with 6-meter diameters, as well as the 15-meter James Clerk Maxwell Telescope and the 10-meter Caltech Submillimeter Observatory, all on the summit of Mauna Kea on the Big Island of Hawaii. All the dishes are linked via fiber optic cable to form an enormous virtual telescope akin to the sum of its parts.
Dec 9, 08: There is a giant black hole at the center of our galaxy, a study has confirmed. German astronomers tracked the movement of 28 stars circling the center of the Milky Way ,27,000 light years in. It's four million times heavier than our Sun.
. . The results suggest that galaxies form around giant black holes in the way that a pearl forms around grit. Dr Massy said: "Although we think of black holes as somehow threatening, in the sense that if you get too close to one you are in trouble, they may have had a role in helping galaxies to form --not just our own, but all galaxies.
Dec 9, 08: A sugar molecule that's linked to the origin of life has been detected in a region of our galaxy where habitable planets could exist. The sweet find is good news in the search for alien life, the researchers say.
. . Called glycolaldehyde, the sugar molecule is considered a life ingredient because it can react with a substance called propenal to form ribose, a central constituent of ribonucleic acid (RNA), which is similar to DNA and considered one of the central molecules in the origin of life.
. . An international team of scientists used the IRAM radio telescope in France to detect glycolaldehyde in a massive star-forming region of space, some 26,000 light-years from Earth.
. . Previously, the organic sugar had been detected toward the center of our galaxy, where conditions are extreme and not conducive to planet-forming compared with the rest of the galaxy.
. . "Possibly, this material is actually rotating around the stars, which may imply that it's a disk and that's where planets may form." She added, "Also the fact that it's just a normal star-forming region suggests that the production of this molecule could be common throughout the galaxy."
Dec 4, 08: Three undergraduate students have discovered a large planet orbiting a fast-rotating star. Extrasolar planet discoveries like this have become common, but this one is unusual both for who found it and the type of star it orbits. It turns out to be the first planet discovered around a fast-rotating star, and it's also the hottest star found with a planet."
. . It's about five times as massive as Jupiter, circles its host star every 2.5 days. It lies at only 3% of the Earth-sun distance from its star, making it very hot and much larger than many other planets.
. . The students detected the exoplanet while testing a method for investigating light fluctuations of thousands of stars in the OGLE database in an automated way.
. . The planet has not been seen directly. But the brightness of one of the stars decreased for two hours every 2.5 days by about 1%. The fast spin makes it difficult to measure the stellar 'wobble' needed to determine the mass of the object orbiting it, and confirming it to be a planet.
Dec 1, 08: A planet outside of the Solar System has been discovered orbiting a dying, puffed-up star called a red giant. To date, about 20 red giants are known to support planets. The finding could help astronomers learn more about the fate of our solar system.
. . The newly discovered exoplanet is nearly six times the mass of Jupiter and orbits the red giant star HD 102272, which is located 1,200 light-years away. The researchers suspect another world is orbiting farther out in the system. If confirmed, the system would be the first red giant star known to support more than one planet.
. . The new planet orbits closer than any other world to its red giant parent, orbiting just 0.6 astronomical units (AU) from the star. The researchers suggest this distance could be the limit, with no planets venturing in closer to a red giant.
. . The host star is currently about 10 times the size of Sol, but it will eventually expand to up to 100 times the size of the sun. Since the star is a relatively young red giant, this mushrooming will probably not take place for another 100 million years, Wolszczan said. At that time, the star's outer shell will engulf this exoplanet.
Nov 25, 08: Astronomers say they have directly imaged a giant exoplanet orbiting its parent star. The announcement comes on the heels of two other reports this month of direct images of planets beyond the Solar System. The new infrared image shows the object as a speck of light near the star Beta Pictoris, which is 70 light-years from Earth, toward the constellation Pictor.
. . "We cannot yet rule out definitively, however, that the candidate companion could be a foreground or background object", said study team member Gael Chauvin of Grenoble Observatory in France. "To eliminate this very small possibility, we will need to make new observations that confirm the nature of the discovery."
Nov 23, 08: CO2, a potential fingerprint of life, has been discovered for the first time in the atmosphere of a planet orbiting another star. However, the planet, HD 189733b, is too hot to be habitable.
. . But the discovery nonetheless has scientists excited, because CO2 is one of four chemicals that life can generate, so being able to detect it shows that astronomers have the ability to find the signs of life on other worlds.
. . Three of the Big Four biomarkers for habitable/inhabited worlds have now been seen: water, methane, and now CO2", explained Alan Boss, a planet-formation theorist at the Carnegie Institution of Washington who was not involved in the finding. "The only one that has not yet been detected is oxygen/ozone."
. . The researchers measured the spectrum of light reflected from the planet's day side by using an interesting trick: They recorded the light of the planet and its star, then recorded it again when the planet was hidden behind the star. The difference revealed what light was coming from the planet.
. . It could be that since it is so close to its star, intense radiation is breaking other chemicals down to create the gas.
Nov 19, 08: An international team of researchers has discovered a puzzling surplus of high-energy electrons bombarding Earth from space. The source of these cosmic rays is unknown, but it must be close to the solar system and it could be made of dark matter.
. . Galactic cosmic rays are subatomic particles accelerated to almost light speed by distant supernova explosions and other violent events. They swarm through the Milky Way, forming a haze of high energy particles that enter the solar system from all directions. Cosmic rays consist mostly of protons and heavier atomic nuclei with a dash of electrons and photons spicing the mix.
. . By the time an electron has traveled a whole kiloparsec, it isn't so 'high energy' any more. High-energy electrons are therefore local.
. . An even more tantalizing possibility is dark matter. There is a class of physical theories called "Kaluza-Klein theories" which seek to reconcile gravity with other fundamental forces by positing extra dimensions. In addition to the familiar 3D of human experience, there could be as many as eight more dimensions woven into the space around us. A popular yet unproven explanation for dark matter is that dark matter particles inhabit the extra dimensions. We feel their presence via the force of gravity, but do not sense them in any other way.
. . How does this produce excess cosmic rays? Kaluza-Klein particles have the curious property (one of many) that they are their own anti-particle. When two collide, they annihilate one another, producing a spray of high-energy photons and electrons. The electrons are not lost in hidden dimensions, however, they materialize in the 3-dimensions of the real world where ATIC can detect them as "cosmic rays."
. . "Our data could be explained by a cloud or clump of dark matter in the neighborhood of the solar system. In particular, there is a hypothesized Kaluza-Klein particle with a mass near 620 GeV which, when annihilated, should produce electrons with the same spectrum of energies we observed."
Nov 18, 08: Dead stars known as magnetars —-the most-magnetic objects in the universe-— are a little less mysterious, thanks to new observations from the European Space Agency's XMM-Newton and Integral space telescopes.
. . Magnetars are are a type of star remnant called a neutron star. They have magnetic fields 10 million times larger than the strongest magnet ever created on Earth. Only 15 of these bizarre objects have ever been spotted.
. . A magnetar forms when an extremely massive star has exhausted its fuel for internal combustion, and collapses into itself. The gravity is so strong that all the matter in the star condenses into neutrons, and the resulting stuff is so dense that a teaspoon of it would weigh about a hundred million tons. "They have the mass of a star, in a radius of only 10 km. They are as dense as nuclear matter, and they rotate extremely fast."
. . On top of neutron stars' already wacky characteristics, magnetars add one more: a magnetic field a thousand times stronger than that of ordinary neutron stars. No one knows why some stars become magnetars, and some experts suggest they may even be the same as regular neutron stars, just seen at a unique phase of life.
Nov 18, 08: Outbursts from the black hole at the center of our Milky Way galaxy generate material that is stretched as it orbits near the gravitational behemoth.
. . New observations from two telescopes provide a better look at what's going on down there. While black holes can't be seen, material swirling into one is superheated, giving off radiation that can be observed. While the Milky Way's black hole is not among the most active in the universe, it is prone to flare-ups.
Nov 13, 08: Telescopes on land have caught the first real visual images of multiple planets orbiting another star. The orbiting Hubble Space Telescope has found its own planet, the first so-called exoplanet to be found purely visually --25 light years from Earth.
. . None of the giant planets would be candidates to host life --they are large and hot, like Jupiter, and orbit far away from their suns. But if large planets are there, astronomers believe at least some of the planetary systems would have smaller, rocky planets like Mars or Earth that are much harder to spot.
Nov 12, 08: The raw ingredients for planets could be created by supersonic shock waves around young stars, a new study suggests.
. . NASA's Spitzer Space Telescope recently examined five baby planetary systems with planets just beginning to form. The observations revealed the presence of tiny quartz crystals that can only form after flash heating followed by rapid cooling, conditions that scientists think could be the result of shock waves of pressure, akin to those from jets that cause sonic booms.
. . The quartz crystals Spitzer found, called cristobalite and tridymite, are some of the building blocks of planets. During the early stages of planet formation, dust grains in the pancake-like disks of dust and gas surrounding young stars crystallize and stick together, eventually snowballing to form a planet.
Nov 5, 08: A computer simulation showing the formation and evolution of a galaxy like the Milky Way points to where scientists should look to spot dark matter. They do not know what it is made of, but think it could be a kind of particle.
. . The international research team looked at a dark matter halo --structures surrounding galaxies which weigh a trillion times more than the sun. Their simulations showed how the galaxy's halo grew through a series of violent collisions between much smaller clumps of dark matter that emerged from the Big Bang.
. . In the densest part of the halo, the dark matter particles collide at high speed to produce a form of radiation called gamma rays. These gamma rays make the halo glow, giving scientists a potential way to detect dark matter.
Oct 27, 08: A nearby star, visible with the unaided eye, is ringed with two rocky planetisimal belts and an outer icy halo, making it a three-ring cosmic circus. The inner planetisimal belt appears to be a virtual twin to the belt in the Solar System.
. . The presence of the separate rings of material around the nearby star, called Epsilon Eridani, suggests unseen planets lurk there, where they confine and shape the rings. The worlds would likely reside within the star's habitable zone.
. . The star is the ninth closest to Sol. Eridani's three nearest known stars are gravitationally bound in a system called Alpha Centauri that's located 4.36 light-years away from us.
. . Epsilon Eridani is slightly smaller and cooler than Sol. And it's also younger. While Sol is an estimated 4.5 billion years old, Epsilon Eridani has been around for just 850 million years.
. . The inner planetisimal belt looks identical to ours in terms of material, and it orbits at 3 astronomical units (AU) from Epsilon Eridani —-the same distance between Sol and the rocky belt between Mars and Jupiter.
. . Epsilon Eridani's second planetisimal belt is 20 AU from the star, or about where Uranus is in relation to our sun, and it is crowded with as much mass as Earth's moon.
. . The outer icy ring, previously observed, extends about 35 AU to 100 AU from Epsilon Eridani and is similar in composition to our Kuiper Belt, a region of icy objects beyond Neptune. Eridani's outer ring holds about 100 times more material than ours, however.
. . Three planets with masses between those of Neptune and Jupiter could be in orbit about Epsilon Eridani. A Jupiter-mass exoplanet was detected in 2000 by the radial velocity method in which astronomers look for wobbling motion of a star due to the gravitational tug of a planet. That planet is located near the edge of the innermost ring.
. . A second planet must lurk near the second planetisimal belt, and a third at about 35 AU near the inner edge of Epsilon Eridani's Kuiper Belt, the researchers say. Terrestrial planets could reside inside the innermost planetisimal belt as well, though there currently is no clear indication of that.
. . Fomalhaut b is about 25 light-years from Earth. It is the 18th brightest star in the sky.
The planet closest to the star weighs in at 10 times the mass of Jupiter, followed by another 10 Jupiter-mass planet and then, farther out, a world seven times the heft of Jupiter. By astronomical standards, the planets are fresh out of the oven, forming about 60 million years ago.
. . "I think there's a very high probability that there are more planets in the system that we can't detect yet."
. . One star is called HR 8799. It’s a bit more massive (1.5 times) and more luminous (5x) than Sol, and lies about 130 light years from Earth. The planets in this picture orbit it at distances of 6 billion km and 10.5 billion km. A third planet, not seen in this image but discovered later using the Keck 10 meter telescope, orbits the star closer in at a distance of 3.8 billion km.
. . It's about 60 million years old. That means the planets are still glowing from the leftover heat of their formation, and that adds to their brightness. Eventually (in millions of years), as they cool, they will glow only by reflected light from the star, and be far harder to see. Fomalhaut b, in the Hubble image, is much older (200 million years), and glows only by reflected light from Fomalhaut. If it were much smaller or dimmer (or closer to the blinding light of the star), we wouldn’t have been able to see it at all.
. . caveats: We now know of more than 300 planets orbiting other stars. And a planet has been imaged before, but it was orbiting a brown dwarf, which is different than a normal star like the Sun. Brown dwarfs are so-called "failed stars", much smaller than the Sun. Another possible planet orbiting a sun-like star has been imaged, but has not yet been confirmed.
. . Kalas thinks there might yet be other planets in orbits between Fomalhaut b and the star; possibly even a planet that could host liquid water on the surface. The James Webb Space Telescope, a large, infrared-optimized space telescope, scheduled for launch in 2013, might just be able to bring such a planet (or planets) into view.
Oct 23, 08: Planets around small mass stars may only have a billion-year window during which life can form. This is the implication of research into the tidal forces that can pull a planet into a tighter orbit around a star.
. . The so-called habitable zone around a star is loosely defined as planetary orbits in which water would be liquid, not vapor or solid, on the planets' surface. These orbits are closer-in for smaller (less bright) stars. However, habitability is not a permanent property of a planet.
. . If some of these migrating planets can be detected, they could provide a test of the Gaia hypothesis, which says that life can force changes to a planet in order to keep it in a habitable state. If astronomers could detect a biosignature (such as an unstable mixture of atmospheric gases) on a planet that had migrated out of the habitable zone, then this might imply that the planet's biology had altered the planet –-maybe by increasing the reflectivity of the atmosphere-– in order to survive.
. . These migrating planets "might tell us something about how life mitigates disasters and adapts to climate change", Barnes says.
Oct 21, 08: Astronomers have long talked about a "habitable zone" around a star as being a confined and predictable region where temperatures were not to cold, not to hot, so that a planet could retain liquid water and therefore support life as we know it. The zone may not be so fixed.
. . Some planets travel non-circular, or elongated paths around their stars. As such a world moves closer to the star, it stretches more, and when it moves farther away, the stretching decreases. When a planet's orbit is particularly oblong, the stretching changes are so great that its interior warms up in a process called tidal heating. The oblong orbits that cause the phenomenon are quite common.
. . "Most of the extrasolar planets we've found so far are in pretty elongated orbits, which is surprising because most of the planets in our solar system have orbits that are roughly circular", Jackson said. Scientists aren't sure why the Solar System is unique in this way.
. . Tidal heating could further boost some planets' habitability by warming them enough to spur volcanism, which in turn drives plate tectonics, the process that recycles rock through a planet's surface layers.
. . Plate tectonics is a definite boon for life, because stirring up the surface layers helps to regulate the amount of CO2 in the atmosphere, since rock absorbs CO2 from the air. And having the perfect balance of CO2 in the atmosphere helps a planet maintain that "just right" temperature range.
Oct 16, 08: In the hunt for extrasolar planets, a new find is shattering records left and right. A planet called WASP-12b is the hottest planet ever discovered, 2,200 degrees C, and orbits its star faster and closer in than any other known world. This sizzling monster whips its way around its parent star about once a day. The planet circles extremely close-in to its star —-about 2% of the distance from the Earth to the sun, in fact, or 3.4 million km. WASP-12b is a gaseous planet, about 1.5 times the mass of Jupiter, and almost twice the size.
. . The planet, which orbits a star 870 light years from Earth, is especially notable because it pushes the bounds of how close planets can ever come to their stars without being destroyed. "There is a limit because as a planet gets closer to its star, the radiation field gets more and more intense, and at some point that whole planet will be evaporated by its star."
. . WASP-12b is one of only about 50 extrasolar planets that have been detected through the transit method, meaning they were found by measuring the dip in brightness of their parent star as they pass in front of it and block part of its light.
Oct 12, 08: The hunt for extraterrestrial life is getting a major boost from revolutionary new technology that will give some of the world's largest telescopes the capability to detect Earth-size planets outside of our solar system, a feat not equaled even by the Hubble Space Telescope.
. . The technique, called nulling interferometry, combines the light captured by several large telescopes to mimic a single giant telescope with enough power to detect a quarter on Luna from Earth.
. . The array of telescopes in Chile's Atacama Desert collectively known as the Very Large Telescope Interferometer (VLTI) is currently being outfitted with a nulling interferometry device called PRIMA. The technology will give the combined telescopes precision equivalent to the distance a human hair grows in a minute — 0.0003 millimeter — from 100 meters away.
. . The US had a big technological lead in nulling interferometry earlier in the decade with plans to install a system to combine the light from the two 10-Meter Keck telescopes and a surrounding array of six smaller telescopes on Mauna Kea in Hawaii. The project was supposed to be completed by 2004, but was stalled by funding cuts at NASA, allowing the Europeans to jump ahead.
Oct 7, 08: Planet-hunters have found "big Jupiters" before; and they have found plenty of small, failed stars --balls of gas that do not have sufficient mass to initiate the nuclear reactions that drive sunlight.
. . But Corot-exo-3b is an in-between object. It is about the size of Jupiter, but packs more than 20 times the mass. As a planet, it would be the most massive and the densest found to date --more than twice as dense as lead. It takes just four days and six hours to orbit its parent star, which is slightly larger than Sol. Scientists say they are not sure if the object is a planet or a type of failed star known as a brown dwarf --neither description really seems to fit.
. . Corot was launched in 2006 and placed in a vantage point some 830km above the Earth. Using its 27cm aperture telescope, it is observing many tens of thousands of stars, looking for the slight drop in light caused by the transit of a planet.
Oct 6, 08: Some observations suggest that galaxies do have the power to expand rapidly. Astronomers found a star factory 12.3 billion light-years away that churns out 4,000 stars per year, compared with our Milky Way's 10 stars annually. That burst of star-making activity suggests such a galaxy would only need 50 million years to grow into one of the largest ever observed.
Sept 23, 08: As if the mysteries of dark matter and dark energy weren't vexing enough, another baffling cosmic puzzle has been discovered. Patches of matter in the universe seem to be moving at very high speeds and in a uniform direction that can't be explained by any of the known gravitational forces in the observable universe. Astronomers are calling the phenomenon "dark flow."
. . Scientists discovered the flow by studying some of the largest structures in the cosmos: giant clusters of galaxies. These clusters are conglomerations of about a thousand galaxies. They discovered that the clusters were moving nearly 3.2 million kph.
Sept 22, 08: Astronomers have long believed that most stars are homebodies which stick close to their birthplaces. But a new simulation supports the suggestion that our sun might have once hitchhiked through the galaxy.
. . Where our sun or another star ends up migrating seems to depend on its position in a spinning spiral galaxy. Stars tagging along behind a massive spiral arm can get a gravitational speed boost that sends them into a bigger orbit around the galactic center. The stars leading in front of a spiral arm may end up getting slowed by the arm's gravitational pull and fall back into a smaller orbit.
Sept 19, 08: Astronomers have confirmed the weight of the most massive star in the galaxy. This behemoth, estimated to be roughly 116 times the mass of the sun, dwarfs most other stars in the galaxy. In fact, the next most massive star is about 89 solar masses, and it is a gravitationally bound sister to the record setter. The next most massive ever weighed is 83 solar masses. Theory holds that stars can be up to about 150 solar masses.
Sept 19, 08: Masses of dust floating around a distant binary star system suggest that two Earth-like planets obliterated each other in a violent collision, U.S. researchers reported. BD +20 307 appears to be composed of two stars, both very similar in mass, temperature and size to the Earth's sun. They spin about their common center of mass every 3 1/2 days or so.
. . "Astronomers have never seen anything like this before; apparently major, catastrophic, collisions can take place in a fully mature planetary system. If any life was present on either planet, the massive collision would have wiped out everything in a matter of minutes: the ultimate extinction event.
. . "This poses two very interesting questions", said Tennessee State's Francis Fekel. "How do planetary orbits become destabilized in such an old, mature system? Could such a collision happen in our own solar system?"
Sept 19, 08: An explosion originating near the edge of the universe has been seen by an orbiting NASA telescope. The burst of gamma rays is the farthest such event ever detected. The burst took 12.8 billion years to reach Earth and so is a snapshot of activity from when the universe was just one-seventh its present age. This one was 70 million light-years farther than the previous record holder.
. . Gamma-ray bursts are the universe's most luminous explosions. Most occur when massive stars run out of nuclear fuel. As their cores collapse into a black hole or neutron star, gas jets -- driven by processes not fully understood -- punch through the star and blast into space. There, they strike gas previously shed by the star and heat it, which generates bright afterglows.
Sept 18, 08: Astronomers have identified the least luminous galaxy known, but it's surprisingly massive. The reason: It is loaded with dark matter, mysterious, unseen stuff that permeates the universe. Astronomers know it's there because of the gravity it creates. Without invoking dark matter, theories can't explain how galaxies stay together.
. . The galaxy, called Segue 1, is one of about two dozen small satellite galaxies orbiting our own Milky Way galaxy. A separate study last month found that all the known satellite galaxies are loaded with dark matter.
. . But among them, Segue 1 is special. It is a billion times less bright than the Milky Way. Yet it's nearly a thousand times more massive than its star light would suggest. It contains only a few hundred stars.
. . In the past two years alone, the number of known dwarf galaxies orbiting the Milky Way has doubled from the dozen or so brightest that were discovered during the first half of the 20th century.
Sept 15, 08: Astronomers have argued for years over whether massive galaxies form from scratch, or by chunking together smaller galaxies.
. . Lately, evidence is building for the latter theory, and a new study adds to the growing picture of galaxy formation as a clumpy affair. Using an array of both ground-based and space telescopes, including ESO's Very Large Telescope in Chile and the Hubble Space Telescope, a team of astronomers recently observed groups of huge galaxies in the process of merging, showing that large, established galaxies can still grow bigger.
Sept 15, 08: Astronomers have taken what may the first picture of a planet orbiting a star similar to the sun. This distant world is giant (about eight times the mass of Jupiter) and lies far out from its star (about 330 times the Earth-Sun distance). The farthest planet in our solar system, Neptune, lies only 30 times the Earth-sun distance away from the sun. It's about 500 light-years from Earth. Though the star has about 85% the mass of the sun, it is younger than our star.
. . Previously, the only photographed extrasolar planets have belonged to tiny, dim stars known as brown dwarfs. And while hundreds of exoplanets have been detected by noting their gravitational tug on their parent stars, it is rare to find one large enough to image directly.
Sept 10, 08: Six months ago, satellite telescopes spotted an exceptionally bright burst of energy that would have been the most distant object in the universe ever visible to the naked eye, if anyone saw it.
. . Even though no humans have reported seeing it directly, the gamma-ray burst, an explosion that signals the violent death of a massive star, is changing theories of how these events look. Gamma ray bursts are typically accompanied by intense releases of other forms of radiation, from X-rays to visible light. This burst, dubbed GRB 080819B, was first detected by the Swift satellite on March 19, while the spacecraft was serendipitously looking at another gamma-ray burst in the same area of the sky.
. . The light it emitted in the visible part of the spectrum was so intense that the burst would have been visible to the naked eye in the constellation Bootes for about 40 seconds —-no other gamma-ray burst has ever been visible without a telescope. It took the light of GRB 080819B about 7.4 billion years to reach Earth --3 billion years before the sun or Earth even formed.
. . Gamma-ray bursts are something of an extreme form of supernovas. Possibly one in every 1,000 supernovae is not one of these "normal" explosions; instead of the star simply dying, its core collapses to form a black hole —-that event generates a gamma-ray burst. It shot material directly toward Earth at 99.99995% the speed of light.
Sept 10, 08: A spectacular nearby star explosion observed in 1843 is now thought to be a previously unknown type of explosion that leaves stars intact.
. . Eta Carinae is a well studied energetic star, some 7,500 light-years away and within our Milky Way Galaxy. It is more than 100 times as massive as our sun, and it's hot and incredibly bright. In cosmic terms, this unpredictable giant is considered to be in our backyard.
. . Eta Carinae brightened incredibly in 1843, and astronomers in recent decades have photographed and studied the resulting cloud of gas and dust, known as the Homunculus Nebula, that billows away from the star. A farther-out faint shell of debris from an earlier explosion is also visible, probably dating from around 1,000 years ago.
. . Smith now proposes that the 1843 event was a true explosion that produced a fast blast wave similar to, but less energetic than, a real supernova.
Aug 28, 08: A violent merger between two galaxy clusters appears to have split ordinary matter from dark matter. NASA's Hubble Space Telescope and Chandra X-ray Observatory show dark matter from each cluster appearing to pass through the cosmic mess unscathed, leaving ordinary matter behind in the galactic pileup. It suggests that dark-matter particles interact only weakly outside of gravity's influence, given that they passed by one another inside the collision zone with little visible effect.
. . The research team also estimated the mass distribution of both dark and ordinary matter by using Hubble's visible-light images. Each cluster boasted almost a quadrillion times the mass of the sun.
Aug 27, 08: A study of small galaxies circling around the Milky Way founnd that while they range dramatically in brightness, they all surprisingly pack about the same mass. The work suggests there is a minimum size for galaxies, and it could shed light on mysterious dark matter.
. . Spinning around the Milky Way are at least 23 pint-sized galaxies, each shining with the light of anywhere from a thousand to a billion suns. Though each of these galaxies is very dim compared to large galaxies like our own, they span a large range in brightness. The finding could help explain the mysterious stuff called dark matter and how it affects the formation of galaxies.
. . Despite their wide-ranging brightnesses, all of the 23 satellite galaxies around the Milky Way seem to have a central mass of 10 million times that of the sun. And what's more, almost all of that mass seems to be made up of dark matter, with just the tiniest smidgen of visible matter producing stars. These dwarf galaxies look more like diffuse, puffy balls of light.
. . The fact that these galaxies, the smallest ever seen, all weigh about the same may mean that there is a lower threshold for the mass of galaxies. Maybe there are no dark matter clumps smaller than these galaxies, and their size represents the critical mass necessary for dark matter to condense into a clump. Another option is that dark matter can form smaller clumps than these, but it just can't give rise to visible-light galaxies.
Aug 20, 08: There is no middle ground when it comes to black holes, which tend instead to be either petite or gargantuan, a new study suggests.
Aug 16, 08: A new map of the halo of stars that surrounds our Milky Way Galaxy has revealed a complicated structure of crisscrossing stellar streams, many of which have never been detected before.
Aug 7, 08: The phenomenon that causes a diamond to sparkle could be used to find large bodies of water on rocky, Earth-like planets, says Darren M. Williams, lead author of a paper in Icarus that describes the process.
. . The trick, he says, is to look for planets when they are in crescent phase, ideally in orbits that lie at an edge-on angle to Earth. In that position, the glare bouncing off the water would make the planet seem unusually bright.
Aug 6, 08: A newly popular theory that suggests the rest of space may teem with microbes. This once-controversial notion holds that the universe is filled with the ingredients of microbial life, and that earthly life first came from the skies as comet dust or meteorites salted with hardy bacteria. "Studies have shown that microbes can survive the shock levels of being launched into space."
. . "One hundred years ago, people wondered if animals could go from one land mass to another", said Cockell. But then people discovered that birds migrate for thousands of miles, that storms carry insects across oceans and seeds between continents. "Panspermia is the next step", he said.
. . Wickramasinghe even concluded that organic material found in comets -- most recently by the Stardust spacecraft, which plucked amino acids from the 81P/Wild 2 comet -- is biological in origin. In other words, the comet is not just a good place for life to grow, but actually contains organic material produced by earlier life, Wickramasinghe believes. That is, of course, hypothetical, and not everyone is convinced.
Aug 4, 08: A Dutch primary school teacher and amateur astronomer has discovered what some are calling a "cosmic ghost", a strange, gaseous object with a hole in the middle that may represent a new class of astronomical object.
. . Made entirely of very hot gas, the eerie green object is illuminated by remnant light from the nearby galaxy. He said light from the past still illuminates the ghostly object, even though the quasar shut down some 100,000 years ago and the galaxy's black hole went quiet. "It's this light echo that has been frozen in time for us to observe."
Aug 4, 08: Scientists have found more intriguing evidence for dark energy —-one of nature's most befuddling phenomena. Dark energy is thought to make up about 74% of the universe, while dark matter. Now they have seen this mysterious force in some of the largest known features of the cosmos, called superclusters and supervoids.
. . The former are particularly crowded areas of space, each with a lot of galaxies huddled in a region half a billion light-years across, while the latter are the opposite, rather barren expanses notably lacking galaxies.
. . Astronomers led by Istv?n Szapudi of the U of Hawaii Institute for Astronomy observed dark energy stretching out these areas by detecting changes in rays of microwave light before and after they passed through the regions. As the researchers predicted, the microwaves were a bit stronger if they had passed through a supercluster, and a bit weaker if they had passed through a supervoid.
July 30, 08: The first object to brighten the dark, primordial universe after the Big Bang was the tiny seed of a star that rapidly grew into a behemoth 100 times more massive than Sol, scientists said.
. . The first generation of stars apparently lived hard and died quickly. While Sol may live 5 billion years, this first generation of stars likely lasted only a slim fraction of that --about 1 million years. The first protostar was born about 300 million years after the Big Bang, the researchers said.
. . Hernquist said these stars may have died in a very bright supernova or might have collapsed in on themselves, forming black holes with relatively little of their material ejected into space as ingredients for future stars.
July 16, 08: A known star has reemerged on the scene as the second brightest in our galaxy and may in fact be the brightest. The "Peony nebula star" shines as brightly as 3.2 million suns, but lurked in obscurity among interstellar gas and dust in the central region of the Milky Way — until now. NASA's Spitzer Space Telescope used infrared vision to scope out the star behind the Peony nebula's reddish cloud of dust.
. . The newcomer is thought to fall short of the current brightest star, Eta Carina, which blazes with the light of 4.7 million suns. But astronomers hold out the possibility that the Peony nebular star may prove even brighter, if they could just get a better look at it.
July 10, 08: Telescopes looking back in time to more than 12 billion years ago have spotted a star factory --a galaxy producing so many new stars that they have nicknamed it the "baby boom" galaxy. Our galaxy cranks out about 10 new stars per year. Now astronomers have found one near the beginning of time that's generating a whopping 4,000 a year.
Jun 17, 08: The invisible stuff called dark matter is thought to make up as much as 90% of the universe's matter. To date, astrophysicists have only inferred the existence of some mysterious substance by identifying its gravitational effects on visible matter such as stars and galaxies. Now, for the first time a team hopes to look inside the sun for one of the prime candidates.
. . Two hypothetical particles have become the prime suspects to explain the fundamental make-up of dark matter: so-called axions and WIMPs (Weakly Interacting Massive Particles). Tens of teams are on the hunt for the heavyweight WIMPs, such as the GLAST team, which hopes to detect the gamma rays produced when, hypothetically, WIMPs and their antimatter selves annihilate each other.
. . Only a handful of groups are searching for the lightweight particles called axions. For both sociological and technical reasons, WIMP searches far outnumber axion ones, according to David Tanner, a physicist at the U of Florida, and others. For instance, he said, detectors for WIMPs build more on the expertise of many astrophysicists. In addition, these massive particles are more fantastical. The axion is extremely lightweight with neither electric charge nor spin, so it hardly interacts with the universe's surrounding matter — that's if the particle even exists.
. . The sun is thought to possibly be a factory for these axions. When photons at the sun's core feel a magnetic field, they become axions, the thinking goes. Since the teensy particles only weakly interact with ordinary matter, they are thought to easily fly through the sun's core toward the surface unimpeded by other particles. Once at the solar corona, where the sun's magnetic field is strong, the axions would convert back into photons.
. . "The axion is so light that it doesn't decay into two photons in free space. However, you can play a very remarkable trick", van Bibber said. "If I shoot a photon into a magnetic field (which you can think of as a sea of virtual photons), a real photon and a virtual photon [interact] to make an axion and vice versa."
. . Evidence that axions exist would not exclude the existence of WIMPs, van Bibber said. "It might be that we live in a universe that is kind of a cocktail, that it might be 90% WIMPs and 10% axions, or fifty-fifty or something like that."
Jun 16, 08: European researchers said they discovered a batch of three "super-Earths" orbiting a nearby star, and two other solar systems with small planets as well. They said their findings suggest that Earth-like planets may be very common.
. . The trio of planets orbit a star slightly less massive than our Sun, 42 light-years away. The planets are bigger than Earth --one is 4.2 times the mass, one is 6.7 times and the third is 9.4 times. They orbit their star at extremely rapid speeds --one whizzing around in just four days, compared with Earth's 365 days, one taking 10 days and the slowest taking 20 days.
. . More than 270 so-called exoplanets have been found. The team also said they found a planet 7.5 times the mass of Earth orbiting the star HD 181433 in 9.5 days. This star also has a Jupiter-like planet that orbits every three years.
. . In addition, HARPS astronomers have tallied about 45 new candidate planets with a mass below 30 Earth masses and an orbital period shorter than 50 days. The researchers say the deluge implies one out of every three sun-like stars harbors such planets. The researchers say about one out of every 14 stars outside our solar system harbors a hot-Jupiter.
Jun 11, 08: Perhaps ET is just a planetary system away, and perhaps all we need is one more telescope to find him. That's the hope, at least, of some scientists who say a new radio observatory being built in Europe may hold a chance of finding alien life beyond our planet.
. . The Low Frequency Array, or LOFAR, is a network of up to 25,000 small antennae being built in the Netherlands, Germany, Sweden, France and the United Kingdom. The distributed radio arrays will collectively scan the universe in the low radio frequency of light when they are completed in 2009.
. . "LOFAR can extend the search for extraterrestrial intelligence to an entirely unexplored part of the low-frequency radio spectrum, an area that is heavily used for civil and military communications here on Earth," said Michael Garrett, general director of ASTRON, the Netherlands Institute for Radio Astronomy and professor of radio techniques in astronomy at Leiden U in the Netherlands. "In addition, LOFAR can survey large areas of the sky simultaneously — an important advantage if SETI signals are rare or transient in nature."
. . So far, the world's most famous alien-hunting telescope, the Arecibo Observatory in Puerto Rico, has been unsuccessful in locating extraterrestrials. The giant dish, which has been listening for radio waves since 1963.
Jun 11, 08: The International Astronomical Union has decided on the term "plutoid" as a name for dwarf planets like Pluto at a meeting of its Executive Committee in Oslo. Sidestepping concerns of many astronomers worldwide, the IAU's decision comes almost two years after it stripped Pluto of its planethood and introduced the term "dwarf planets" for Pluto and other small round objects that often travel highly elliptical paths around the sun in the far reaches of the solar system.
. . The dwarf planet Ceres is not a plutoid as it is located in the planetisimal belt between Mars and Jupiter. Current scientific knowledge lends credence to the belief that Ceres is the only object of its kind, the IAU stated. Therefore, a separate category of Ceres-like dwarf planets will not be proposed at this time, the reasoning goes.
Jun 9, 08: While the number of confirmed extrasolar planets is now approaching 300, the tally of extrasolar moons so far identified is still a rather disappointing zero. But the search is not impossible, says Darren Williams, associate professor of physics and astronomy at Penn State Erie, the Behrend College. Williams believes a moon in orbit around a known extrasolar planet will also be detectable if we look hard enough with the right techniques. "It will add a periodic component to the combined infrared signal" of the planet-moon system, he said.
. . It's possible, for example, that life could exist on extrasolar moons, researchers say. And it has been suggested that the ocean tides induced by Earth's moon may have been necessary to create the conditions for life on our planet to begin.
. . Future missions, such as NASA's Terrestrial Planet Finder and The European Space Agency's Darwin, will have the ability to return the valuable data required both for finding other Earths and, Williams figures, some moons.
Jun 6, 08: A team of physicists has claimed that our view of the early Universe may contain the signature of a time before the Big Bang. The discovery comes from studying the cosmic microwave background (CMB), light emitted when the Universe was just 400,000 years old. Their model may help explain why we experience time moving in a straight line from yesterday into tomorrow.
. . The microwave background is mostly smooth, the Cobe satellite in 1992 discovered small fluctuations that were believed to be the seeds from which the galaxy clusters we see in today's Universe grew.
. . Dr Adrienne Erickcek, and colleagues, now believes these fluctuations contain hints that our Universe "bubbled off" from a previous one. Their model suggests that new universes could be created spontaneously from apparently empty space. From inside the parent universe, the event would be surprisingly unspectacular. Co-author Professor Sean Carroll explained that "a universe could form inside this room and we’d never know".
. . The inspiration for their theory isn't just an explanation for the Big Bang our Universe experienced 13.7 billion years ago, but lies in an attempt to explain one of the largest mysteries in physics --why time seems to move in one direction.
. . Much work remains to be done on the theory: the researchers' first priority will be to calculate the odds of a new universe appearing from a previous one. Detailed measurements made by the satellite have shown that the fluctuations in the microwave background are about 10% stronger on one side of the sky than those on the other. Sean Carroll conceded that this might just be a coincidence, but pointed out that a natural explanation for this discrepancy would be if it represented a structure inherited from our universe's parent.
Jun 3, 08: Quark stars, exotic objects that have yet to be directly observed, are part of a new theory to explain some of the brightest stellar explosions recorded in the universe.
Jun 3, 08: For decades, astronomers have pictured our galaxy as sporting four major, spiral arms, however new images effectively sever two appendages, revealing the Milky Way has just two major arms.
Jun 2, 08: Astronomers have sighted the smallest extrasolar planet yet orbiting a normal star - a distant world just 3.3 times the size of our own. Researchers want to find other worlds that could host life.
. . The new planet orbits a star which is itself of such low mass that it may be a "failed star" known as a brown dwarf. Astronomers found the new world using a technique called gravitational microlensing.
May 28, 08: The Milky Way galaxy weighs slightly less than 1 trillion times as much as our sun, according to a new estimate. Previous estimates had ranged from 750 billion solar masses to up to 2 trillion.
. . The new estimate is based on a large sample of stars in the galactic halo, a relatively sparse sphere of stars that surrounds our galaxy's main disk. The speeds of stars in the halo reveal the mass of the galaxy by allowing astrophysicists to infer the amount of gravity required to keep those stars in orbit.
May 19, 08: A tiny star recently unleashed what is considered the brightest burst of light ever seen in the universe from a normal star other than the sun, astronomers announced. Shining with only 1% of the sun's light and boasting just a third of the sun's mass, this run-of-the-mill star previously was nothing to write home about. On April 25, the red dwarf star, known as EV Lacertae, unleashed a mega-flare, packing the power of thousands of solar flares. "Flares like this would deplete the atmospheres of life-bearing planets, sterilizing their surfaces."
. . The star, with an estimated age of a few hundred million years, has a history of flares, though none as bright as the most recent one. The giant flares are powered by energy stored in EV Lacertae's magnetic field, say NASA scientists involved in the recent discovery. The star rotates once every four days, much faster than the sun's four-week rotation. The star's quick rotation generates strong localized magnetic fields, about 100 times as powerful as the sun's.
May 15, 08: Astronomers have known about interstellar dust for a while, but they haven't been able to quantify just how much light it blocks. Now a team of researchers has studied a catalogue of galaxies and found that dust shields roughly 50% of their light.
. . Dust is made up of lumps of carbon and silicates that form dust grains only a few thousandths of a millimeter long. It hangs out in galaxies, but generally steers clear of the space between them.
. . They counted the number of galaxies in the catalogue that were directly facing us, and compared it to the number that were tilted 90 degrees away from us. Without dust, they reasoned, they should see just about equal numbers of galaxies in each orientation. But with dust, they would likely find fewer edge-on than face-on galaxies. Since dust lies in the disks of spiral galaxies, and not the dense central bulge, when we view galaxies from the side we are looking through thicker layers of dust, so we should see less light. In fact, the researchers counted about 70% fewer edge-on galaxies than face-on galaxies.
May 14, 08: About 140 years ago, our time, a stellar explosion lit up our galaxy with a blinding flash of light, sending out powerful shock waves to boot. Now, astronomers have spotted the youthful remains from the explosion. The newly discovered remains mark the youngest known supernova remnant in the Milky Way. The shell of hot gas and high-energy particles glows as X-rays, radio waves and other wavelengths of radiation for thousands of years. The astronomers estimate the centenarian is hiding out about 1,000 light-years from the galactic center, or roughly 25,000 light-years from us.
. . Two or three supernovae should light up the Milky Way every century, resulting in about 60 supernova remnants younger than 2,000 years old. To date, just 10 such remnants have been confirmed.
. . Supernovae and their remnants are critical for creating and distributing the majority of the elements in the universe through the interstellar medium, spreading everything from cobalt to gold to radium to planets, plants, people and far beyond.
May 12, 08: Astronomers have found a piece of the universe's puzzle that's been missing for awhile: a type of extremely hot, dense matter that is all but invisible to us. Engaging in something like cosmic accounting, astronomers have tried to balance the scant amount of matter that has been directly observed with the vast amount that remains unobserved directly. The latter constitutes about 90% of the universe's matter.
. . Dark matter remains a total mystery. But the new study squares the balance sheet a bit in regards to baryonic matter. Previously, only about half of the baryonic matter in the universe was accounted for by the known gas, stars and galaxies. A team of astrophysicists has now found evidence of part of the missing half in a bridge-like filament connecting two clusters of galaxies.
. . Along with dark matter, the missing baryonic matter is thought to form an enormous spider web of tendrils that connect galaxy clusters, which sit on threads and knots in the web. The missing part of this matter was thought to be a hot, ultra-thin gas haze of very low density between larger structures. Its hellacious temperature means that it only emits far-ultraviolet and X-ray radiation.
. . A similar baryonic haze, 150 times hotter than the sun's surface, was indirectly detected surrounding the Milky Way and connecting about three dozen other galaxies known collectively as the Local Group. It is thought that these hot intergalactic hazes were created from material that did not fall into galaxies when they first formed more than 13 billion years ago.
May 6, 08: In a distant galaxy, a star orbiting a massive central black hole strays too close to the insatiable giant and is torn apart. But before it can be devoured, the star lets out one last flare of light that slowly moves across the galaxy. Astronomers on Earth pick up this faint call and use it to map the nucleus of the galaxy from which it emanated.
. . The team is still monitoring the "light echo", and for the first time, one of these events can be observed in great detail, allowing astronomers "to probe different regions of the galaxy." Galactic nuclei are normally hard to resolve because a permanent accretion disk of dust and gas around the black hole illuminates everything simultaneously. "But this light echo effect makes different components shine up temporarily, but ... at different times.
May 2, 08: Scientists might be giving up on the notion of sending ridiculously large pieces of glass into space. Using a Fresnel-zone lens instead, astronomers at Observatoire Midi Pyrenees in France propose to take extremely high-contrast images at vast distances without a large lens or mirror. A 30-meter Fresnel telescope will provide visual confirmation of Earth-like planets up to 30 light years away. Since it can also observe a wide spectrum range including UV and IR, it can do follow-up detection of life signs, too. The main advantage of the Fresnel telescope is, of course, the fact that it's a perforated sheet of roll-up metal instead of heavy, breakable glass. But there are some major reasons it's not super easy to just whip up one of these telescopes in the machine shop:
. . Though a Fresnel sensor has the same sharpness as a glass lens, it only collects about 10% of the light. That's why the sheet has to be really really big, like the 30-meter one mentioned above. Even worse, the Fresnel lens brings light to focus far away from its own surface. A 30-meter panel may require a spaceship with secondary lens and camera located several kilometers away to line up within a few millimeters to capture the image precisely on camera. That's some tricky flying, and would require a lot of energy, especially when the panel itself is constantly tilting to look at new, wondrous things.
Apr 29, 08: A colossal black hole has been spotted exiting its home galaxy, kicked out after a huge cosmic merger took place. When two colliding galaxies finally merge, it is thought that the black holes at their cores may fuse together too. Astronomers have theorized that the resulting energy release could propel the new black hole from its parent galaxy out into space
. . Eventually, the black holes would fuse, and "in the final coalescence, or merger, of these two black holes, a giant burst of gravitational waves is emitted", she said. "Since these waves are generally emitted in one preferred direction, the black hole is then kicked in the other direction." It can propel the black hole to speeds of up to several thousand kilometers per second, according theoretical simulations. The escaping black hole Komossa and her team observed was racing along at 2,650 kilometers per second.
. . In theory, these mergers and escapes would leave several black holes without galaxies and galaxies without black holes out in space. In simulations where a black hole receives a slightly weaker kick, it can't escape the galaxy's gravity, so it falls back and oscillates until it comes to rest again at the galaxy's core.
Apr 29, 08: Several newfound galaxies seen as they existed when the universe was young are packed with improbable numbers of stars. Astronomers don't know what's going on.
. . The nine galaxies are 11 billion light-years away, which means the light astronomers are looking at left the galaxies 11 billion years ago, when the universe was less than 3 billion years old.
. . Each of the newly studied galaxies weighs about 200 billion times the mass of the sun yet is a mere 5,000 light-years across. Our Milky Way Galaxy is a fraction of that heft at roughly 3 million times the sun's mass, and yet it stretches across 100,000 light-years of space.
. . Shortly after the theoretical Big Bang, the universe contained an uneven landscape of dark matter. Hydrogen gas became trapped in puddles of the invisible material, the thinking goes, and began spinning rapidly in dark matter's gravitational whirlpool, forming stars at a furious rate.
Apr 23, 08: Using powerful radio telescopes, scientists have captured a supermassive black hole just as it was belching out a jet of supercharged particles, offering a first look at how these cosmic jets are formed, they said.
. . Supermassive black holes form the core of many galaxies and astronomers have long believed they were responsible for ejecting jets of particles at nearly the speed of light. But just how they did it had remained a mystery.
. . A kind of supermassive black hole known as a blazar was suspected of spewing out a pair of forceful streams of plasma. What they saw was a close up of this charged material winding in corkscrew fashion out of the supermassive black hole, behaving just as astronomers had predicted.
Apr 21, 08: Alien life may well exist in a primitive form somewhere in our corner of the galaxy, famed astrophysicist Stephen Hawking said. Given the size of the universe, it is unlikely that Earth is the only planet to develop some sort of life, Hawking told an audience at George Washington U in Washington, D.C. He added that humanity must embrace space exploration, if only to ensure its long-term survival.
. . The lack of success by the Search for Extra-Terrestrial Intelligence (SETI) project to discover signals from an alien civilization suggests that none exist within several 100 light-years of Earth, Hawking said, though he offered three theories on the dearth of interplanetary communications.
. . The probability of primitive life developing on a suitable planet may be extremely low, or it may be high, but aliens intelligent enough to beam signals into space may also be smart enough to build civilization-destroying weapons like nuclear bombs, he said. More likely, he added, is that primitive life is likely to develop, but intelligent life as we know it is exceedingly rare.
. . Sending astronauts back to Luna, establishing a lunar base with a clear target of going on to Mars would do much to restore the public's support for spaceflight, he added. "If the human race is to continue for another million years we will have to boldly go where no one has gone before", Hawking said.
Apr 18, 08: Baby stars have been discovered spawning in the otherwise barren outskirts of a galaxy. The finding has surprised astronomers because the galactic periphery was assumed to lack high concentrations of ingredients needed to form stars. They are forming from 100,000 light-years from M83's center, & up to 140,000 light-years.
Apr 16, 08: The odds of intelligent life arising on another Earth-like planet are low, a British scientist has calculated. Prof Watson completed his PhD under the supervision of James Lovelock, author of the Gaia hypothesis, "whose view of the earth as a whole system has influenced me ever since".
. . His model has echoes of the Drake equation, a formula for predicting the number of civilizations in our galaxy with which we might hope to be able to communicate. The answer depends on the fraction of stars in our galaxy which have planets that can support life, the time it would take for them to release detectable signals into space, and other variables. Based on the values used by Frank Drake and his colleagues in 1961, the number of detectable civilizations was ten, in the Milky Way alone.
Apr 15, 08: There is a slumbering matter-munching monster in the middle of our galaxy, and every once in a while, this black hole flares up and releases plumes of X-rays.
. . Matter is constantly falling into the Milky Way's central supermassive black hole, but sometimes enough builds up and gets hot enough to release a big flash. For instance, if humans had an X-ray observatory 300 years ago, we would have seen a giant flash caused by a clump of gas heating up as it fell toward the black hole.
. . Although we missed this mighty burst, astronomers have recently spotted echoes of it in a large gas cloud called Sagittarius B2. The X-rays took 300 years to travel from the central black hole to the cloud, and when they arrived, they collided with iron atoms, causing them to emit X-rays.
Apr 7, 08: Astronomers have discovered a planetary system orbiting a distant star which looks much like our own. They found two planets that were close matches for Jupiter and Saturn orbiting a star about half the size of our Sun. The finding suggested systems like our own could be much more common than we thought. And he told a major meeting that astronomers were on the brink of finding many more of them.
. . The OGLE planets were found using a technique called gravitational micro-lensing, in which light from the faraway planets is bent and magnified by the gravity of a foreground object, in this case a another star.
Apr 7, 08: Some of the most massive stars might not explode as supernovae, a new study suggests. Rather, researchers speculate, they simply collapse into black holes or if they do generate explosions, they're not as intense as the deaths of less massive stars.
. . More massive stars explode in massive supernova explosions. The new finding suggests that stars of around 20 to 30 times the mass of the sun might not explode at all, but rather collapse to form black holes.
. . The research, which also asserts that stars as small as seven times the mass of the sun still apparently have enough fuel to "go supernova". NASA and other sources frequently cite eight solar masses as the lower limit for supernova generation.
. . If the astronomers find a star at the location of the later explosion, they can work out the mass and type of star from its brightness and color. Several such stars have been identified before they exploded, and the Queen's team studied the nature of five of them.
. . However, in their analysis, the team found no very massive stars that had exploded, suggesting that the red supergiant stars between 18 and 30 solar masses may instead collapse to form black holes.
Apr 10, 08: Brown dwarfs are the oddballs of the cosmos, more massive than planets but not heavy enough to generate the thermonuclear fusion that powers real stars. Now astronomers have found the coldest brown dwarf to date. The failed star might represent a new class of objects that are a missing link between planets and stars.
. . The cold brown dwarf floats freely in space, not bound to a star ...about 40 light-years away. Its mass is somewhere between 15 and 30 times that of Jupiter. And it is about 350 Celsius.
The surface of the sun is about 6,000 degrees C. The temperature at the top of Jupiter's clouds is about -145 degrees C, though at its core the mercury soars to 24,000 degrees C.
. . Clouds of dust and aerosols, as well as large amounts of methane, were detected in the atmospheres of the coolest brown dwarfs, just as in the atmosphere of Jupiter and Saturn.
. . However, there were still two major differences. In the brown dwarf atmospheres, water is always in gaseous state, while it condenses into water ice in giant planets; and ammonia has never been detected in the brown dwarf, while it is a major component from Jupiter's atmosphere.
. . The newly-discovered brown dwarf looks much more like a giant planet than the known classes of brown dwarfs, both because of its low temperature and because of the presence of ammonia.
. . To date, two classes of brown dwarfs have been known: the L dwarfs --temp of 1,200-2,000 C-- which have clouds of dust and aerosols in their high atmosphere, and the T dwarfs (temp lower than 2,100 F), which have a very different spectrum because of methane forming in their atmosphere.
. . Because it contains ammonia and has a much lower temperature than do L and T dwarfs, CFBDS0059 might be the protoype of a new class of brown dwarfs to be called the Y dwarfs, the researchers propose.
Apr 10, 08: Douglas Vakoch, Director of Interstellar Message Composition, SETI Institute
. . As the search for extraterrestrial intelligence (SETI) enters a new phase, with the recent start of observations for radio signals from other worlds with the SETI Institute's Allen Telescope Array, the international scientific community has begun preparing all the more earnestly for the cascade of events that would follow the detection of an alien civilization. Among the most important questions humankind will ponder on that day is whether we should reply, and if so, what we should say.
. . A message from extraterrestrials will include their suggestions for a reply. After all, the reasoning goes, they will probably have made contact with many other civilizations before us, so they will be well versed in the productive first steps in interspecies communication.
. . But what could we say that would be of interest to extraterrestrials? Before we answer that question, we must acknowledge that any extraterrestrials we make contact with may well be thousands or millions of years more advanced than we are. Why do SETI scientists assume this? Because for our search to succeed, it needs to be true.
. . If other civilizations transmit evidence of their existence for only a few decades ? the length of time that humans have been capable of interstellar communication ? and then they lose the interest or ability to make contact, it's extremely unlikely that the precise time they are transmitting and the time that we are listening will coincide. On a galactic scale, where time is measured in billions of years, it is extremely unlikely that these two "blips" would happen at the same time.
Apr 9, 08: If you thought one black hole was scary, be very afraid, because triple black-hole mergers are a real possibility in the universe, according to a new supercomputer calculation. Astrophysicists used a computer model to predict what would happen if several black holes were to orbit each other. Often the trio would merge into one giant black hole.
Apr 9, 08: The smallest planet discovered outside the Solar System has been found by Spanish scientists. "I think we are very close, just a few years away, from detecting a planet like Earth", team leader Ignasi Ribas told a news conference.
. . The rocky planet, with a radius about 50% greater than the Earth's, circles a small red dwarf star 30 light years away. The planet, known as GJ 436c, was found by analyzing distortions in the orbit of another, larger planet around the star GJ 436, a technique similar to that used more than 100 years ago to discover Neptune.
. . With a mass about five times greater than Earth's, it is the smallest planet yet discovered outside the solar system and improving techniques are opening the way to discovering worlds ever more like our own. "In a very short time, we are going to be able to see a planet with the same mass as the Earth, although it's going to be in an orbit much closer to its star than that of the Earth around the sun, so it won't strictly be a planet like the Earth."
. . It orbits close to its small, relatively cool star once every five Earth days. Its rotation means 22 Earth days pass between each time the red dwarf star rises on its horizon --so its days are four times as long as its years.
Apr 2, 08: A new discovery of a middleweight black hole suggests black holes come in all sizes. Astronomers have long debated the existence of a class of middleweight black holes, which could be a missing link in the evolution of the universe's first stellar black holes to supermassive black holes that anchor most major galaxies.
. . Data gathered by instruments on the Hubble Space Telescope and the Gemini South telescope in Chile show that the sky's largest star cluster, Omega Centauri, might harbor an elusive intermediate-mass black hole in its center.
. . The entire cluster contains about 10 million stars tightly bound by gravity, making Omega Centauri among the biggest and most massive of some 200 globular clusters orbiting the Milky Way. These clusters tend to house mostly ancient stars and are thought to be remnants of the early universe.
. . They calculated Omega's total mass to be far higher than expected based on the number and type of stars seen. The researchers suspect the missing mass comes from a black hole weighing 40,000 solar masses at the center of the cluster.
Apr 2, 08: Ten worlds were identified by a group of astronomers in the past six months using earthbound instruments.
. . Instead of spending weeks babysitting single stars to seek out gravitational wiggles, as many planet-hunters do, some European astronomers are monitoring millions of stars with inventive camera setups such as one called SuperWASP. "SuperWASP is now a planet-finding production line."
. . The planets range in mass from half the size of Jupiter to more than eight times the size of Jupiter, the largest planet in our solar system. One orbits its sun once a day and is so close that its daytime temperature could reach about 2,300 degrees Celsius.
. . They found a baby planet while using radio astronomy to examine a disk of gas and rocky particles around the star HL Tau. This star is thought to be young, also --100,000 years old compared to our 4.6 billion-year-old Sun.
. . They found a clump that appears to contain rocky pebbles. The protoplanet is about 14 times as massive as Jupiter and is about twice as far from HL Tau as Neptune is from our Sun."
Apr 1, 08: NASA scientists have identified the smallest, lightest black hole yet found. The new lightweight record-holder weighs in at about 3.8 times the mass of our sun and is only 24 km in diameter. It sits in a binary system.
. . astronomers can weigh black holes by using a relationship between the apparent size of the black hole and the X-rays emitted by the torrent of gas that swirls into the black hole's disk from its companion star.
. . As it is squeezed, the gas heats up and radiates X-rays. The intensity of the X-rays varies in a pattern repeated over a nearly regular interval. Astronomers have long suspected that the frequency of this signal, called the quasi-periodic oscillation, or QPO, depends on the mass of the black hole. As the black hole gets bigger, the zone of swirling gas is pushed farther out, so the QPO ticks away slowly. But for smaller black holes, the gas sits closer in and the QPO ticks rapidly.
. . Astronomers know that some unknown critical threshold, possibly between 1.7 and 2.7 solar masses, marks the boundary between a star that generates a black hole upon its death and one that produces a neutron star.
Seth Shostak: The best guess of the exoplanet specialists is that the number of Earth-size planets in our galaxy exceeds tens of billions. Planets are not great new habitat, because they're spheres. They're cursed with the minimum surface area for their mass. As pointed out three decades ago by Gerry O'Neill, it's both more efficient and enormously cheaper to build artificial habitats in your home star system.
Mar 27, 08: Astronomers have peered into the womb of a stellar disk to capture an image of material falling onto what could be a planet in an early stage of formation.
. . The new image shows a somewhat horseshoe-shaped void in the disk surrounding a young star called AB Aurigae. Within the void, a barely visible bright spot could indicate a developing object that's currently between 5 and 37 times the mass of Jupiter. If this object is a planet, the image does not show the planet itself. Oppenheimer said the image shows what's thought to be dust accreting onto the object. Boss speculates the object is more likely a brown dwarf.
. . The star AB Aurigae is quite young, estimated to be between 1 million and 3 million years old. Our sun, by comparison, is 4.6 billion years old, but most of the planet formation in our solar system is thought to have taken place in the first hundred million years or so.
Mar 21, 08: A powerful stellar explosion that has shattered the record for the most distant object visible to the naked eye was detected by NASA's Swift satellite. The explosion, known as a gamma-ray burst, also ranks as the most intrinsically bright object in the universe ever observed by humans.
. . "It's amazing —-we've been waiting for a flash this bright from a gamma-ray burst ever since Swift began observing the sky three years ago, and now we've got one that is so bright that it was visible to the naked eye even though its source is half-way across the universe."
. . Gamma-ray bursts are the most luminous explosions in the universe since the Big Bang and occur when massive stars run out of nuclear fuel. The stars' cores collapse to form black holes or neutron stars and release an intense burst of high-energy gamma-rays and jets of energetic particles.
. . "If this burst had happened in our galaxy, it would have been shining brighter than the Sun for almost a minute —-sunglasses would definitely be advised." The afterglow of GRB 080319B was 2.5 million times more luminous than the most luminous supernova ever recorded, making it the most intrinsically bright object ever recorded.
. . Astronomers have placed the star in the constellation Bootes. They have estimated it to be 7.5 billion light years away from Earth, meaning the explosion took place when the universe was less than half its current age and before Earth formed.
Mar 19, 08: A carbon-containing molecule has been detected for the first time on a planet outside our Solar System. The organic compound methane was found in the atmosphere of a Jupiter-sized planet orbiting a star some 63 light years away. Water has also been found in its atmosphere, but scientists say the planet is far too hot to support life.
. . Under certain circumstances, methane can play a key role in prebiotic chemistry --the chemical reactions considered necessary to form life.
. . The observations were made as the planet passed in front of its parent star, as viewed from Earth. As the star's light passed briefly through the planet's atmosphere, the gases imprinted their chemical signatures on the transmitted light.
. . The number of known planets orbiting stars other than our own now stands at about 270.
Mar 18, 08: Scientists have detected water vapor in the spinning disks that surround two newly formed stars, where planets are born. The spinning disks of particles may eventually coalesce to form planets. These initial observations portend more to come. "We were surprised at how easy it is to find water in planet-forming disks once we had learned where to look."
Mar 18, 08: The term "planetary nebula" has always been a misnomer, but these spectacular clouds of dust and gas may actually have something to do with planets after all, astronomers have found.
. . When astronomers discovered these celestial objects 300 years ago, they couldn't tell what they were and so named them for the resemblance they had to the planet Uranus as seen through early, relatively crude telescopes. But by the mid-19th century, it was realized that they were actually great clouds of dust emitted by dying stars.
. . Now, researchers at the U of Rochester have found that low-mass stars or possibly even giant gas planets orbiting these aged stars could be pivotal in creating some of the nebulae's unusual shapes.
. . "Planetary" nebulae are the last stage of life for most medium-sized stars, such as our Sun. This stage only lasts for several tens of thousands of years—a blink of an eye in the star's 10 billion year lifespan. Of the 200 billion stars in the Milky Way, only about 1,500 have been found to be in the nebula phase.
. . The stage begins as the star depletes its fuel near the end of its life. Its core contracts and its envelope expands, eventually throwing off its outermost layers millions of miles into space.
. . One time in five, the envelope keeps its spherical shape as it expands, forming a glowing orb. But more often, the envelope contorts into a dazzling array of shapes. [does this imply that 80% of those stars have planets?!] Blackman and his team explored the role that low-mass companion stars or super-Jupiter-sized planets might have in sculpting the shapes of planetary nebulae.
Mar 12, 08: If the nearest star system, Alpha Centauri, does harbor rocky planets similar to Earth as new findings suggest, there exist a host of ways to get us there, in theory.
. . Conventional rockets are nowhere near efficient enough. At a maximum speed of about 28,300 kph, it would take the space shuttle, for example, about 165,000 years to reach Alpha Centauri. In any case, "the problem with conventional rockets is that if you're carrying fuel, you need fuel just to carry all the fuel you bring with you, and it just gets exponentially worse", Landis said.
. . But antimatter engines might work. These drives rely on the extraordinary amount of energy released when antimatter and matter annihilate each other. The problem, however, is creating enough and storing any antimatter for the trip.
. . "All of the current methods of manufacturing antimatter require enormous particle accelerators and produce antimatter in very small quantities", Landis said. "And to store antimatter, if you need a ton of magnets for one gram of antimatter, the entire idea of a lightweight way to store immense amounts of energy is no longer lightweight. If even the tiniest amount ever leaked out and touched the walls surrounding it, the whole thing catastrophically goes away."
. . Instead of rockets that carry all their fuel with them, spaceships might scoop it up along the way. One design proposed by physicist Robert Bussard (who died last year) would employ giant electromagnetic fields to suck in hydrogen to fuel a nuclear rocket.
. . Unfortunately, this "ramscoop" or Bussard ramjet, probably could not work. "The interstellar medium is not as dense as Bob Bussard thought it would be", Landis said. "And so far all attempts to design some kind of scoop had the unfortunate effect of producing more drag than you get back thrust, working kind of like parachutes." Moreover, "we don't really have any notion of how to use the pure hydrogen we find in interstellar space as fusion fuel."
. . Light sails might be another way to go —-giant, thin, lightweight reflective sails that rely on the slight push provided by light beams. "The point is to not carry the energy you need for propulsion with you, but to get it transmitted to you." Instead of relying just on the enormous amount of light given off by the sun, light sails to Alpha Centauri could also ride laser beams. Very powerful and extraordinarily large lasers are needed in order to focus on sails that get farther and farther away.
. . "Pulsed propulsion" would hurl bombs behind a ship, which is shielded with a giant plate. The explosions would push against the plate, propelling the ship. Project Orion suggested using nuclear bombs, while other proposals have since proposed smaller explosives.
. . It might easily take more than one lifetime to reach the star system —-one antimatter engine design would take 200 years to send humans there. If that proves so, mission designers might have to take sex and family into account so offspring of the original crew would be around at the end of the trip, unless someone successfully invents a technique for placing people in suspended animation.
Mar 11, 08: A Nasa space probe measuring the oldest light in the Universe has found that cosmic neutrinos made up 10% of matter shortly after the Big Bang. Five years of study data also shows that the first stars took over half a billion years to light up the Universe.
. . WMAP launched in 2001 on a mission to measure remnants of light left over from the Big Bang. This is the oldest light in the Universe, shifted to microwave wavelengths as the Universe expanded over 13.7 billion years.
Mar 10, 08: "It may explode any time within the next few hundred thousand years." When the Wolf-Rayet goes supernova, "it could emit an intense beam of gamma rays coming our way", Tuthill said. "If such a 'gamma ray burst' happens, we really do not want Earth to be in the way." Since the initial blast would travel at the speed of light, there would be no warning of its arrival.
. . Gamma ray bursts are the most powerful explosions known in the universe. They can loose as much energy as our sun during its entire 10 billion year lifetime in anywhere from milliseconds to a minute or more.
. . The spooky thing about this pinwheel is that it appears to be a nearly perfect spiral to us, according to new images taken with the Keck Telescope in Hawaii. "It could only appear like that if we are looking nearly exactly down on the axis of the binary system."
. . Gamma rays would not penetrate Earth's atmosphere well to burn the ground, but they would chemically damage the stratosphere. Melott estimates that if WR 104 were to hit us with a burst 10 seconds or so long, its gamma rays could deplete about 25% of the world's ozone layer, which protects us from damaging ultraviolet rays.
. . Gamma ray bursts would also trigger smog formation that could blot out sunlight and rain down acid. However, at 8,000 light-years away, "there's probably not a large enough effect there for much of a darkening effect", Melott estimated. "It'd probably cut off 1 or 2% of total sunlight. It might cool the climate somewhat, but it wouldn't be a catastrophic ice age kind of thing."
. . If a gamma ray burst was pretty close, any high-energy particles would blast right through the galaxy's magnetic field and hit us", Melott said. "Their energies would be so high, they would arrive at almost the same time as the light burst. The side of the Earth facing the gamma ray burst would experience something like getting irradiated by a not-too-distant nuclear explosion, and organisms on that side might see radiation sickness.
. . Future research should focus on whether WR 104 really is pointed at Earth and on better understanding how supernovae produce gamma ray bursts. Melott and others have speculated that gamma ray bursts might have caused mass extinctions on Earth. But when it comes to whether this pinwheel might pose a danger to us, "I would worry a lot more about global warming", Melott said.
Mar 7, 08: Earth may have a twin orbiting one of our nearest stellar neighbors, a new study suggests. . . U of California, Santa Cruz graduate student Javiera Guedes used computer simulations of planet formation to show that terrestrial planets are likely to have formed around one of the stars in the Alpha Centauri star system, our closest stellar neighbors. The model also showed that if such planets do in fact exist, we should be able to see them with a dedicated telescope.
. . Guedes' model showed planets forming around the star Alpha Centauri B (its sister star, Proxima Centauri, is actually our nearest neighbor) in what is called the "habitable zone", or the region around a star where liquid water can exist on a planet's surface.
. . The metallicity of Alpha Centauri B (or how much of its matter is made up of elements heavier than hydrogen and helium) is higher than our Sun's, so there would be plenty of heavier-mass material for planets to form from, he said.
. . Also, because the planet is a triple star system, the processes that form large Jupiter-mass gas giants, which account for most of the extrasolar planets found so far, would be suppressed. So it would be more likely for the system to produce terrestrial planets.
. . Because Alpha Centauri B is so bright and nearby, detecting a small terrestrial planet's miniscule wobble would be that much easier. Also, its position high in the sky of the Southern Hemisphere means it is observable for most of the year, just as the Big Dipper is observable for most of the year in the Northern Hemisphere.
. . According to Laughlin, five years of observations using a dedicated telescope would be needed to detect an Earth-like planet around Alpha Centauri B. If astronomers do dedicate substantial resources to detecting an Earth-like planet, this is the star to focus on, he added.
. . If such a planet is found, spacecraft, such as the proposed Terrestrial Planet Finder, could be launched to find out more information about the world, such as whether or not it had water on its surface.
Mar 4, 08: There just happens to be a binary star about 8,000 light years from us that's on the brink of exploding. Not a big deal normally, but this one happens to have its pole pointed right at us, which means that if it explodes in a gamma-ray burst it could shoot a beam of destructive, ozone-layer-melting gamma rays at us all Death-Star-like.
. . There are enough ifs involved in the situation to make the likelihood pretty slim, but this is definitely one of those situations that astronomers are keeping a careful eye on. It all revolves around WR 104, a humungous star classified as a Wolf Rayet star. Generally, these blow up as a supernova, which is no biggie. But sometimes, they blow up as gamma-ray bursts.
. . Models of a GRB exploding at roughly the same distance indicate that the immediate impacts are damage to the ozone layer, and the creation of nitrogen dioxide, which is basically smog. Gamma rays emitted by the burst would hit ozone molecules and shatter them, and models indicate that a GRB at this distance could deplete the ozone layer by 30% globally, with local pockets depleted by 50%. It would take years for the ozone to recover from that. Note that the ozone holes we have been dealing with the past few years are actually depletions of less than 5%. Obviously, this is a big deal.
. . The good news is that we don't know when it's going to explode, be it tomorrow or 20,000 years from now, and we don't know how it'll explode either. Basically, the chances are really slim that anything bad will happen.
Mar 4, 08: Cosmic magnifying glasses called gravitational lenses help scientists zoom in on far-away scenes they could never spot otherwise. In a recent survey of a section of the universe, researchers counted 67 new gravitational lenses, leading them to believe there are nearly half a million similar lenses in the rest of the universe. "It's like a second telescope in front of your telescope."
. . The 67 newly discovered lenses are caused by large galaxies, although clusters of galaxies often produce strong gravitational lenses too. "You can think of the lenses as glass beads", Capak said. "If you hold up a glass bead and look thorough it, it distorts the picture behind it.
Mar 3, 08: For the first time, astronomers have pinpointed the spot where the intense winds of two massive stars in a binary system violently collide and detected the production of high-energy X-rays there. The monstrously large Eta Carinae binary contains between 100 and 150 times the mass of Sol and glows more brightly than four million sols together. The so-called hypergiant contains two massive stars, the second of which was not discovered until 2005.
. . Astronomers have long suspected that the stellar pair should give off high-energy X-rays, but until now, they didn't have the instruments to detect the radiation. But the European Space Agency's Integral telescope, launched to detect some of the most violent events in the universe, has conclusively detected such X-rays emanating from Eta Carinae, more or less as astronomers had thought.
. . The stellar winds of Eta Carinae can reach speeds of 1,500 to 2,000 km per second. Because the two stars are in such close proximity, the winds collide in a ferocious shockwave where temperatures reach several billion degrees Kelvin.
. . "In our galaxy, there are probably only 30 to 50 colliding-wind binaries that display a clear signature of wind-wind collision." Astronomers estimate that the Eta Carinae system loses one Earth mass per day of ejected material.
Feb 28, 08: If aliens had an antenna-farm that was 25km on a side consisting of a collection of rooftop TV antennas spaced every 3 meters, and receivers as noise-free as those we build for our radio telescopes, they could pick up our TV carriers in two minutes of listening from 50 light-years away. That, incidentally, is where the earliest episodes of "I Love Lucy" are hanging out now.
. . If they found the carrier too boring, and wanted to actually watch Lucy drive Desi nuts, they'd need an antenna farm 150 times bigger in each direction. That's a large herd of antennas, approximately the size of the US.
. . By 2030, radio astronomers hope to have a radio telescope in Europe that's a square kilometer in size. With that rate of improvement, we should be building antennas of the dimensions needed to at least detect TV-strength signals from tens of thousands of star systems by the second half of this century.
. . NASA's recent broadcast of Beatles music to Polaris (the North Star). For this, the space agency used the 65 meter Deep Space Network antenna near Madrid, Spain, and a mere 20 kilowatts of transmission power. In order for the Polarians, if there are any, to notice that this unsolicited serenade is washing over their planet, they'll need an antenna about 12 km across. Polaris, of course, is not next door. Its 430 light-years distant. There are about 100,000 stellar systems that are closer.
Feb 27, 08: Two scientists think they have decoded the gassy recipe to create stars as much as 100 times bigger than the sun, perhaps solving the mystery of their formation. They used mathematical models to show how small stars can prime superstar formation. "Gravity tends to break interstellar gas clouds into small pieces, preventing massive star formation", Krumholz said. "But little stars heating up a gas cloud can smooth it out, forcing gravity to create a huge star."
. . Although massive stars are about a million times rarer than the most common stars —-those about 80% smaller than the sun-— they are the movers and shakers of the universe. "They're the things that can push around and heat up interstellar gas, which is essentially where all stars come from." He also explained that big stars seed the cosmos with elements that are required for life. "They enrich the universe with metals from their supernovae."
. . "We estimate the number of stars in a galaxy on the amount of light we see, and if massive stars are missing, then it's possible that we've dramatically underestimated the rate of star formation in distant regions of the universe."
Feb 19, 08: The first stars to appear in the Universe may have been powered by dark matter, according to US scientists. Normal stars are powered by nuclear fusion reactions, where hydrogen atoms meld to form heavier helium. But when the Universe was still young, there would have been abundant dark matter, made of particles called Wimps: Weakly Interacting Massive Particles. These would have fused together and obliterated each other long before nuclear fusion had the chance to start. . . As a result, the first stars would have looked quite different from the ones we see today, and they may have changed the course of the Universe's evolution --or at least held it up. The theory depends on particles that astronomers can't see, but are certain exist, and physicists have never detected. But the indirect evidence for their existence is overwhelming.
. . The nature of the first stars has long puzzled astronomers. Immediately after the Big Bang, the Universe expanded and cooled, so that for millions of years it was filled with dark, featureless hydrogen and helium --and perhaps Wimps. Astronomers can see that there were normal stars 700 million years after the Big Bang.
. . The new paper says reactions between the Wimps, colliding and annihilating each other, would have generated enough heat to keep the protostars inflated --like hot air balloons. And as more Wimps rained down on them the heating would have kept going. These giant, diffuse stars could have filled the orbit of the Earth.
. . The details of what the stars would have looked like have yet to be worked out. But in five years' time, Nasa will launch its James Webb Space Telescope (JWST), the successor to the Hubble Space Telescope, and that might be able see right back to these "dark" stars. There is also the intriguing possibility, says Professor Freese, that in some corner of our local Universe, there may be a few survivors lurking unnoticed.
Feb 18, 08: Using the Spitzer Space Telescope, researchers looked for signs of hot dust at distances plausible for planet formation around various stars, categorized by age. They found that warm dust at that distance was relatively common around stars that were 10 million to 20 million years old, but that it fell off almost entirely by the time stars were about 300 million years old. That's about the right time scale to correspond with the time the Earth and other planets are believed to have formed slowly through the collision of smaller bodes, out of the Sun's own dust cloud.
. . At worst, it appears to show that at least one out of five Sun-like stars has the potential for forming rocky planets, they said. An optimistic interpretation might be that some massive discs of dust would form planets more quickly –-and in that case, up to 62% of stars could be planet-forming.
Feb 15, 08: Astronomers and amateur stargazers have used an unusual technique to find a planetary system that closely resembles our own and say it may be a new and more productive way to scour the universe for planets --and life. They said technique, called microlensing, shows promise for finding many more stars, perhaps with Earthlike planets orbiting them.
. . Two planets of similar size and orbit to Jupiter and Saturn. It is the first time microlensing has been used to find two planets orbiting a single star 5,000 light-years away from Earth. The star is smaller, dimmer and fainter than our sun and the two planets are less massive than Jupiter and Saturn, but orbit at distances similar to the distances that Jupiter and Saturn orbit our own sun. "So it looks like a scale model of [the] Solar System", Gaudi said.
. . "Microlensing works by using the gravity of the star and the planet to bend and focus light rays from a star behind it", Gaudi said. "If you are looking at one star and another passes in the foreground (gravity from the front star) will focus and bend light rays. That causes the background star to be magnified", he added. Any planets orbiting the star cause "a little bump" in this magnification effect, Gaudi said. In this case, the light from the more distant star was magnified 500 times. The discovery suggests these planets are common.
. . The 80-odd members of the Optical Gravitational Lensing Experiment worked frantically night after night during the 11-day period from late March through early April 2006 when the two stars were close enough to one another, as viewed from Earth, to cause the microlensing effect.
. . "We tried to get 24/7 coverage of the event", said Andrew Gould, professor of astronomy at Ohio State University. "It gets to be dawn in one place and we have to get somebody observing in another place."
Feb 12, 08: Astronomers have glimpsed what may be the farthest galaxy we've ever seen, providing a picture of a baby galaxy born soon after the beginning of the universe. Images taken with the Hubble Space Telescope have revealed the galaxy at almost 13 billion light-years away, making it the strongest candidate for the most distant galaxy ever seen.
. . The discovery was made possible by a natural magnifying glass —-the galaxy cluster Abell 1689, which lies between us and the distant galaxy. Abell 1689's gravity is so strong it bends light that passes near it, acting like a giant zoom lens that magnifies what we see.
Feb 11, 08: The two biggest mysteries in cosmology may be one. A new theory says that dark matter and dark energy could arise from a single dark fluid that permeates the whole universe. And this could mean Earth-based dark matter searches will come up empty.
. . Dark energy is needed to explain the more recently-discovered acceleration of the universe's expansion. It supposedly exists all throughout space, delivering a pressure that counteracts gravity. It's counterintuitive that one substance could be both a gravitational anchor for galaxies and anti-gravity force for the universe. However, HongSheng Zhao of the U of St Andrews in Scotland claims that a fluid-like dark energy can act like dark matter when its density becomes high enough.
. . "Dark energy is a property of the vacuum —-of fields that we do not easily see", Zhao said. "From it, we can derive the dark matter effect." Zhao compares this dark fluid to Earth's atmosphere. Atmospheric pressure causes air to expand, but part of the air can collapse to form clouds. In the same way, the dark fluid might generally expand, but it also could collect around galaxies to help hold them together.
. . It's similar to one that Pedro Ferreira of the U of Oxford and his colleagues devised a few years ago. "[Our theory] involves positing a preferred time direction, in some sense a special time frame", Ferreira said. "It has the interesting effect of modifying Einstein's theory of general relativity."
. . The idea is similar to the "ether", an invisible medium that physicists once thought light waves travelled through. Einstein's relativity did away with the need for such a medium, but cosmologists have recently found that an ether-like substance can mimic dark matter.
. . The presence of such a substance changes the way gravity works. This is most noticeable in the distant outskirts of a galaxy, where the galaxy's gravitational pull would be expected to be small, but the ether makes it much stronger. The ether "effectively softens space-time in regions of low [gravitational] acceleration making it more sensitive to the presence of mass than usual", Ferreira explained. Zhao has refined this approach and found that it can match a lot of astronomical data.
. . But the fluid does affect the speed at which galaxies can rotate. Some 75 years ago, astronomers noticed that galaxies were turning faster than would be expected from the amount of normal light-emitting matter they contained. The answer seemed to require some form of unseen dark matter. However, Zhao has shown that his fluid can keep galaxies from flying apart just as well as dark matter can.
. . Zhao has also tested his model against the bullet cluster of galaxies, where a massive collision appears to have stripped hot gas from its dark matter envelope. This "naked" dark matter was seen as iron-clad proof for traditional dark matter theories, but Zhao claims that his fluid can reproduce the same effect. Chris Boehmer from University College London thinks it "compelling" that Zhao's model can reproduce so much galaxy data.
. . If the dark fluid is mimicking dark matter, then scientists are searching in vain for the elusive dark matter particle, often called a WIMP (for weakly interacting massive particle). Currently, several experiments are trying to detect a rare collision of a WIMP on Earth or observe gamma rays from distant WIMP self-annihilations.
. . But not many cosmologists are ready to abandon dark matter just yet. The dark fluid idea is still fairly new, so some issues have yet to be worked out, whereas dark matter is a fairly mature theory. "The current [dark matter] model provides the best fit to the data and is therefore the best model at hand", Boehmer said.
. . However, Boehmer agrees that having two unknowns —-dark matter and dark energy-— make up 95% of the universe is a bit embarrassing for cosmology. "Frankly speaking, these are just fancy words we use to name something we do not understand", he said. If a simpler model (with a single word) can explain all the data, then cosmologists will gladly accept it, Boehmer said.
Feb 4, 08: A telescope arms race is taking shape around the world. Astronomers are drawing up plans for the biggest, most powerful instruments ever constructed, capable of peering far deeper into the universe —-and further back in time-— than ever before.
. . The building boom, which is expected to play out over the next decade and cost billions of dollars, is being driven by technological advances. The super-sized telescopes will yield even finer pictures than the Hubble Space Telescope.
. . Two new technologies: The first is adaptive optics. It allows telescopes on the ground to get rid of the distortion caused when looking through Earth's thick atmosphere into space.
. . The second breakthrough involves technology that makes bigger mirrors possible. Instead of casting a giant mirror in one piece, which is difficult and limits size, astronomers now make smaller mirror segments and piece them together. This technique is going from 36 segments in current telescopes to 492 segments with his new project.
. . The European Extremely Large Telescope. A partnership of European countries called the European Southern Observatory already has telescopes in Chile and is aiming for a new one with a mirror of 42 meters, scaled back from initial plans of 100 meters. The Europeans are aiming for a 2018 completion.
Feb 4, 08: Dr HongSheng Zhao, of of St Andrews U's School of Physics and Astronomy, has shown that the puzzling dark matter and its counterpart dark energy may be more closely linked than was previously thought. Only 4% of the universe is made of known material --the other 96% is traditionally labelled into two sectors, dark matter and dark energy. A British astrophysicist and Advanced Fellow of the UK's Science and Technology Facilities Council, Dr Zhao points out, "Both dark matter and dark energy could be two faces of the same coin.
. . In Dr Zhao's model, dark energy and dark matter are simply different manifestations of the same thing, which he has considered as a 'dark fluid'. On the scale of galaxies, this dark fluid behaves like matter and on the scale of the Universe overall as dark energy, driving the expansion of the Universe. Importantly, his model, unlike some similar work, is detailed enough to produce the same 3:1 ratio of dark energy to dark matter as is predicted by cosmologists.
. . "The search for dark-matter particles so far has concentrated on highly-energetic particles. If dark matter however is a twin phenomenon of dark energy, it will not show up at instruments like the LHC, but has been seen over and over again in galaxies by astronomers."
. . However, the Universe might be absent of dark-matter particles at all. The findings of Dr Zhao are also compatible with an interpretation of the dark component as a modification of the law of gravity rather than particles or energy.
Jan 30, 08: A young star speeding away from the Milky Way is in fact an alien visitor, astronomers have confirmed. The wayward object is one of several rogues that are giving astronomers a glimpse into the volatile nature of our galaxy and others.
. . Astronomers have found about 10 stars hurtling away from our galaxy, at speeds that exceed its gravitational grasp. While most stars rush through space at speeds on the order of hundreds of kilometers per second, these aptly-named "hypervelocity stars" are rocketing away at least twice as fast. Most of these speedy stars are thought to be exiles from the center of our galaxy, flung out into intergalactic space by the powerful forces of the massive black hole at the center of our galaxy.
. . The theory was that binary star systems at the galaxy's center would occasionally wander too close to the massive black hole looming there, which would disrupt their orbital dance. While one of the pair was captured by the black hole, the other would be sent rocketing off at an incredible speed. "That's the only way you can accelerate a star to go thousands of kilometers per second." By examining the age of these exiled stars, astronomers concluded that they seem to have had time to come from the center of our galaxy.
. . Of these 10 strange stars, one, dubbed HE 0437-5439, seemed a bit stranger than the rest. Based on its current position, the star would have to be 100 million years old to have come from the center of the Milky Way. But it is only 35 million years old.
. . Bonanos and Lopez-Morales took a closer look at the elemental composition of the star and found that it seemed to be a visitor from our small galactic neighbor, the Large Magellanic Cloud. But while the elemental profile matched, there's one big conundrum: The LMC "is not known to have a massive black hole that could eject it."
. . Another strange consequence of these roving stars is the contradiction they provide to the long-held notion that intergalactic space is pretty much empty. 'There seem to be all these stars flying around between galaxies", Bonanos said. If stars are shot out from our galaxy, they are likely propelled from others, she says, though we are unlikely to be able to see them because stars are too hard to individually identify from the distance of most galaxies.
. . So far, all of the hypervelocity stars found are moving away from us, but they could be shot out of the galaxy's center in any direction, up or down from the galactic plane, or even toward us.
Jan 27, 08: Explosions of small stars, long thought to create stellar dust, actually sweep dust away, scientists discovered. For years, researchers have observed swirling dust clouds around systems called recurring novas, which periodically explode. New images of a distant nova have now overturned astronomers' long-standing assumption that the dust originates in the blasts.
Jan 16, 08: A new map reveals dense pools of invisible matter tipping the scales at 10 trillion times the mass of the sun and housing a cosmic city of ancient galaxies. The map provides indirect evidence for so-called dark matter and how this mysterious substance affects galaxy formation.
. . Scientists theorize that dark matter, considered to make up about 85% of the universe's matter, acts as scaffolding on which galaxies mature. As the universe evolves, the tug from dark matter's gravitational field causes galaxies to collide and swirl into superclusters.
. . "The dark matter halos are what allow the galaxies to form in the first place. The dark matter is the underlying skeleton of the universe," said Meghan Gray of the University of Nottingham. "Most of the universe is dark matter. Galaxies are just froth on this ocean of dark matter."
. . By averaging the shape-distortions from the thousands of galaxies, the researchers found four pools of dark matter. And the invisible clumps matched up with the location of hundreds of ancient galaxies, which have experienced a violent history in their passage from the outskirts of the supercluster into the central hubs.
. . The galaxies in the central hubs, they are finding, show signs of aging, as they are elliptical, red in color and are no longer forming stars. Disk galaxies reside on the outskirts of the supercluster. These youthful galaxies are blue-hued and buzzing with star birth. It's these young galaxies that constantly fall into the supercluster, adding to its galactic girth.
Jan 15, 08: Supermassive black holes spin at speeds approaching the speed of light, new research suggests. Nine huge galaxies were found to contain furiously whirling black holes that pump out energetic jets of gas into the surrounding environment, according to a study. They can drag material around them at close to the speed of light.
. . Einstein's theory suggests spinning black holes would make space itself rotate. The overall effect makes gas spiral in toward the black hole, and also creates a magnetic field that shoots inflowing gas back out as a jet.
. . Researchers previously found that the greater the amount of gas falling into supermassive black holes —-known as the accretion rate-— the greater the energy of the jets shooting out. The jets produced by such high-speed spins heat the surrounding gaseous atmosphere and can help trigger the birth of stars. However, such powerful jets could also destroy the atmospheres of neighboring planets.
Jan 11, 08: New work by a team of US astronomers has shown that wherever there is room for a planet to form around a young star, it does.
. . The researchers predicted the existence of an unknown planet circling a star more than 200 light-years from Earth. This prediction was based on a study of the orbits of two planets already known to orbit the star HD 74156. They then observed the system and confirmed there was a new planet just where they predicted it would be. The find represents the first time astronomers have successfully forecast the existence of an unknown planet since Neptune was predicted in the 1840s.
. . They found that planets' orbits tend to be as closely packed together as they can be. There is a limiting factor on packing: if planets huddle too closely together, gravity will start to destabilize their orbits. The researchers reasoned that there must be universal rules applying to how planets form around young stars.
. . When they looked at two planets, called "b" and "c", already identified orbiting the star HD 74156, they found that there was a large gap between them. If the scientists' "Packed Planetary Systems" theory was correct, there should be a planet between "b" and "c", and in a particular orbit around its parent star.
. . "This is a new way to find planets. And more speculatively, it might be a new way to try and search for life. It may be a coincidence, but this new planet was found inside the habitable zone (around its parent star)."
. . Another group of astronomers has since found another planet where Dr Barnes and his colleagues had predicted one to be in another system they had considered during their analysis. The team also forecast the presence of a planet in a stable region around the star HD 38529, and Dr Barnes said he hoped this would be confirmed soon, too.
Jan 11, 08: A colossal cloud of gas is racing toward a collision with our galaxy, and when it hits, the crash could trigger an intense burst of star formation. The collision and stellar light show will occur in 20 million to 40 million years.
. . The cloud, dubbed Smith's Cloud after the astronomer who discovered it in 1963, is just 8,000 light-years from our galaxy's disk. Jam-packed with enough hydrogen to make a million stars like the sun, it is 11,000 light-years long and 2,500 light-years wide. "My guess is that this [gas cloud] is a remnant of the original formation of the Milky Way in the way that comets and meteors are remnants of the formation of the solar system", said Jay Lockman.
. . If you could see the cloud, it would span 30 times the width of Luna. Since the cloud is made of cold gas, it emits only in the radio wavelengths, Lockman said. It does not generate any visible light.
. . Results showed Smith's Cloud is plunging into the Milky Way, not heading out. And it's falling in at more than 869,000 kmph. Tidal forces of gravity, like the moon tugging on Earth, pull the front parts of an object greater than the regions on the far side. He said the cloud would likely strike a region somewhat farther from the galactic center than our solar system.
Jan 11, 08: Antimatter, which annihilates matter upon contact, seems to be rare in the universe. Still, for decades, scientists had clues that a vast cloud of antimatter lurked in space, but they did not know where it came from. The mysterious source of this antimatter has now been discovered —-stars getting ripped apart by neutron stars and black holes.
. . These gamma rays apparently came from a cloud of antimatter roughly 10,000 light-years across surrounding our galaxy's core. This giant cloud shines brightly with gamma rays, with about the energy of 10,000 suns.
. . Their new findings suggest these positrons originate mainly from stars getting devoured by black holes and neutron stars. As a black hole or neutron star destroys a star, tremendous amounts of radiation are released. Just as electrons and positrons emit the tell-tale gamma rays upon annihilation, so too can gamma rays combine to form electrons and positrons, providing the mechanism for the creation of the antimatter cloud, scientists think.
. . The researchers calculate that a relatively ordinary star getting torn apart by a black hole or neutron star orbiting around it —-a so-called "low mass X-ray binary"-— could spew on the order of one hundred thousand billion billion billion billion positrons (a 1 followed by 41 zeroes) per second. These could account for a great deal of the antimatter that scientists have inferred, reducing or potentially eliminating the need for exotic explanations such as ones involving dark matter.
Jan 11, 08: Research findings from this week's annual meeting of U.S. astronomers range from blue orphaned baby stars to menacing "rogue" black holes that roam our galaxy, devouring any planets unlucky enough to be within their limited reach. The odds of one of these black holes swallowing up Earth or the sun or wreaking other havoc is somewhere around 1 in 10 quadrillion in any given year.
. . One example is an approaching gas cloud. The cloud has a mass 1 million times that of the sun. It is 47 quadrillion miles away. But it's heading toward our Milky Way galaxy at 150 miles per second. Photos of "blue blobs" that astronomers figure are orphaned baby stars. They're called orphans because they were "born in the middle of nowhere" instead of within gas clouds.
Jan 11, 08: Two old stars may be undergoing a second episode of planet formation, long after their initial window of opportunity. Astronomers believe the stars once had orbiting companions, but that these were engulfed when the stars expanded. This caused matter to be ejected from the stars, forming a disc of dust and gas from which planets could form anew.
Jan 10, 08: A quartet of stars has been discovered in an intimate cosmic dance, swirling around each other within a region about the same as Jupiter's orbit around the sun. Astronomers say a gaseous disk might have once engulfed and pushed the stars into their tight orbits. Though bright, the stellar system was thought to be a single star. Each of the stars is about half as massive as Sol and older than 500 million years.
. . Since most stars form as part of a multiple-star system, the new findings could have implications for understanding the evolution of stars.
. . Two of the stars were orbiting each other at 483,000 km per hour, taking a under a mere five days to complete an orbit. The other couple had an orbit speed of 193,000 km per hour and takes about 55 days for a complete jaunt around their common gravitational midpoint in space.
. . The researchers say that fewer than 1 in 2,000 stars observed might be involved in such intimately bound systems. In fact, the spin energy of the more rapidly rotating pair, mixed with the gravitational interaction between the two pairs, has pushed the other pair farther away over the years.
Jan 10, 08: New discoveries in a strange spiral galaxy show it has a pair of arms winding backward compared to the typical direction for most galaxies. Most spiral arms observed so far tend to trail in the wake of their galaxy's spin, meaning they wind in the direction opposite the rotation.
Jan 10, 08: A half-dozen hefty black holes hide out where they are least expected, in relatively skinny galaxies. The discovery implies galaxies don't need bulging bellies to harbor monstrous black holes.
Jan 9, 08: The most massive black hole in the universe tips the cosmic scales at 18 billion times more massive than the sun, astronomers suggest today. Even though researchers suggested black holes up to this mass might exist in quasars, this is the first direct confirmation of such a behemoth. The hefty gravity well is six times more massive than the previous record and is orbited by a smaller black hole, which allowed the measurement of the giant's mass.
. . The binary black hole system powers a quasar known as OJ287, which is located 3.5 billion light-years from us.
. . There is a simple physical explanation for the 12-year pulsing. "In addition to the primary back hole in the [accretion] disk, we have a secondary black hole that crosses the disk twice during the orbital period", Valtonen said. "And that's what gives us the two pulses."
. . Our home galaxy could be chockfull of rogue black holes that devour anything that crosses their paths, new computer simulations suggest.
Jan 9, 08: When two black holes merge, under certain conditions the energy produced can kick the newly merged black hole clear out of its galaxy at jaw-dropping speeds, the simulations suggest. The masked fugitive is called a rogue black hole. "Rogue black holes like this would be very difficult to spot. Unless it's swallowing a lot of gas, about the only way to detect the approach of such a black hole would be to observe the way in which its super-strength gravitational field bends the light that passes nearby", she said.
. . Some mergers would also create gravitational waves, which would be strong enough to hurl the merged black hole at speeds as high as 4,000 km per second).
. . Results showed that even if every globular cluster in our galaxy started out with an intermediate-sized black hole, only 30% of these would hold onto them through a merger.
. . Taking the speculation a step further, if the roughly 150 to 200 globular clusters known to reside in the Milky Way have spawned intermediate-sized black holes, 100 or more of them are probably wandering invisibly around our galaxy, the researchers conclude.
Jan 9, 08: An extrasolar planet about one-fourth the heft of Jupiter might have formed from the collision and merger of two planets, astronomers announced. The object orbits a brown-dwarf star called 2M1207A located 170 light-years from Earth.
. . Astronomers have long puzzled over the mysterious object, which seems to fall outside the spectrum of physical possibility. Its temperature, age and brightness don't match up with what astrophysical theory would predict.
. . Researchers have debated since 2004 what exactly the object is, however — whether it's a planet or perhaps a brown dwarf, which is a failed star and not a planet. Past estimates put the object's mass at about five times that of Jupiter. However, the new study, if accurate, suggests the object weighs less than Jupiter. If the new model is correct, it would mean 2M1207B formed in a similar fashion to a planet. It would also means that a 2004 picture of the object would go down in history as the first photo of a planet outside our solar system.
. . This titanic-collision theory would explain why 2M1207B is a feverish 2,400 degrees Fahrenheit (1,315 degrees Celsius) even though it's had possibly 8 million years or so since formation to cool off. It should have cooled to 704 degrees C by now. A smashup between a Saturn-sized gas giant and a planet about three times the size of Earth could explain the extra heat.
. . From nudges to colossal crashes, such encounters are common. "Most, if not all, planets in our solar system were hit early in their history", Mamajek said. Perhaps most notably, a collision created Earth's moon. And another knocked Uranus on its side.
. . They estimate the object has a radius of 50,000 km with a mass of about 80 times that of Earth. And the only way for such a small object to remain so hot so long after its birth is if it suffered a recent, titanic collision that heated it, they say.
Jan 8, 08: Brilliant blue blobs weighing tens of thousands of solar masses have been found lurking in the seemingly barren expanse of intergalactic space. The "eyes" of the Hubble Space Telescope resolved the objects, which appear to be clusters of stars born in the swirls and eddies of a galactic smashup some 200 million years ago.
. . The mysterious star clusters are considered orphaned, as they don't belong to any particular galaxy. Instead, they are clumped together into a structure called Arp's Loop along a wispy bridge of gas stretched like taffy between three colliding galaxies —-M81, M82 and NGC 3077. These galaxies are located about 12 million light-years from us. "We could not believe it, the stars were in the middle of nowhere."
. . Astronomers had not considered the gas tendrils thick enough to accumulate enough material needed to build so many stars. But the new images reveal they hold the star-equivalent of five Orion Nebulae.
. . While more massive than most open clusters housed inside galaxies, the blue blobs are just a fraction of the mass of globular star clusters that orbit a galaxy. The astronomers estimate that many of the clusters' stars are as young as 10 million years and younger. Our sun, for comparison, is 4.6 billion years old.
. . De Mello and her colleagues suggest galactic collisions and the turbulent aftermaths might have triggered the starbirth. In fact, it was about 200 million years ago that M81 and M82 had their last encounter.
Jan 8, 08: Astronomers have spotted small galaxies near the beginning of time that resemble ancestors of our own galactic home. The tiny galaxies are about one-tenth to one-twentieth the size of the Milky Way and have 40 times fewer stars. Light from the ancient clusters was emitted about 2 billion years after the Big Bang.
. . "Finding these objects and discovering that they are a step in the evolution of our galaxy is akin to finding a key fossil in the path of human evolution", said Eric Gawiser. The spiral galaxies, which are made mostly of hot, bright stars that emit a unique "Lyman alpha" signature of ultraviolet light.
Jan 8, 08: An explosive star within our galaxy is showing signs of an impending eruption, at least in a cosmic time frame, and has for quite some time. From 1838 to 1858, the star called Eta Carinae brightened to rival the light of Sirius, the brightest star in the sky, and then faded to a dim star. Since 1940 it has been brightening again, and scientists think Eta Carinae will detonate in 10,000 to 20,000 years.
. . Fortunately, Eta Carinae is far away, at least 7,500 light-years from Earth. If it explodes, most of its energy will be scattered or absorbed in the vast emptiness of space. It also happens to be tilted about 45 degrees from the line of sight to Earth, so any type of gamma-ray burst, a high-energy outburst expected with this star's eventual eruption, would miss the Earth. Cosmic rays would be diffused by magnetic fields, and most of the damaging light would not affect life on Earth.
. . SN 2006gy was the brightest supernova ever recorded until an even brighter one was discovered in November. Astronomers now know the progenitor of SN 2006gy was remarkably similar to Eta Carinae. They warn a superluminous supernova might explode right in our own galaxy.
Jan 7, 08: Astronomers have found the first signature of complex organic molecules in the dust cloud around a distant star, suggesting that these building blocks of life may be a common feature of planetary systems. In the Solar System, the large carbon molecules, called tholins, have been found in comets and on Saturn's moon, Titan, giving its atmosphere a red tinge.
. . Tholins are thought to be precursors to the biomolecules that make up living organisms on Earth (though they are no longer found on our planet because the oxygen in our atmosphere would quickly destroy them).
. . It's a massive 8-million-year-old star about 220 light-years from Earth. Its dust disk, discovered in 1991, is considered a prime example of a planetary system in formation.
Jan 2, 08: The mysterious origins of cosmic rays that slam into the Earth's atmosphere could soon be revealed, thanks to a better ground-based sensor that costs less than balloons or satellites. Cosmic rays are thought to come from either the center of the galaxy or a nearby supernova, and knowing which is true will help astrophysicists paint a more accurate picture of the cosmos.
Jan 2, 08: Astronomers say they have discovered the youngest planet to date circling a sun-like star, a find that will be a boon to the field of planet-formation theory. The extrasolar planet is an estimated 8 million to 10 million years old, a mere toddler compared to Earth, which is 4.5 billion years old. Until now, the researchers say, no planet younger than 100 million years old has been detected circling a sun-like star.
. . The newly found world is so infantile that it resides in the star's "protoplanetary disk"; a ring of gas and dust circling the star. Weighing in at nearly 10 Jupiter masses, the planet circles at a distance of .04 Astronomical Units (AU) from its host star, TW Hydrae. The gassy "hot Jupiter" takes 3.56 days to orbit its star. The host star is located 180 light-years away.
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