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By Daniel Fischer Every page present in Europe & the U.S.!
| Ahead | Awards 
The latest issue!
| A German companion! (SuW version) Current mission news: MGS (latest pictures!) + Cassini + Galileo + NEAR |
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2nd pulsar linked to observed supernovaUntil now the Crab pulsar was the only one for which actual observations of the supernova exist that created it - but now there is a 2nd clearcut case: The X-ray observatory Chandra with its high resolution has located a pulsar exactly at the geometric center of the supernova remnant G11.2-0.3. This location provides very strong evidence that the pulsar, a neutron star spinning 14 times per second, was formed in the supernova of 386 AD which left the remnant, making it 1,615 years old. The stellar explosion had been observed by Chinese astronomers - one of less than 10 reliably observed supernovae over the past 2000 years. In the 1970's the supernova remnant was found and in 1997 the pulsar, but only now has it been possible to make a connection.Since pulsars move rapidly once they are formed, Chandra's ability to pinpoint the pulsar at the remnant's center implies the system must be very young. While this is exciting by itself, it also raises new questions about pulsars, especially during their infancies. For if one applies the present spin rate of the pulsar to current models to determine the pulsar's estimated lifetime, the result is an age of roughly 24,000 years - far predating the birth year of 386 AD. To explain this contradiction, the Chandra team argues that this pulsar may have had approximately the same spin rate today as it did at its birth. If true, this could have important implications for conventional wisdom regarding pulsars, which may be spinning more slowly than previously thought. |
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Two new multi-planet systems the most bizarre yetThe leading team of planet-hunting astronomers has announced the discovery of two multi-planet systems that are among the most bizarre found to date. One system calls into the question the very meaning of the term "planet", and the second system has two planets eternally locked in sync, with orbital periods of 60 and 30 days. Both systems were known previously to contain one planet, but now appear to have two planets each orbiting a central star; only one multi-planet system apart from our own had been known until now (see Update # 126 for the discovery).One of the systems is around the sun-like star HD 168443: The star is orbited by both a massive planet and another bulkier object at least 17 times more massive than Jupiter, the largest planet orbiting the Sun. Whether this bulky companion is a planet, a dim failed star called a brown dwarf or some as-yet unidentified astronomical object is unclear. The two objects orbiting HD168443 have masses of at least seven and 17 times that of Jupiter. They have eccentric orbits, as do most planets around other stars, residing 0.3 and 3 AU from the star. The larger planet wasn't detected until now because several years of data were needed in order to see the wobble created by its 4.7-year orbit. Around a second star the team discovered a pair of planets locked in resonant orbits, moving in synchrony around their star with orbital periods of 60 and 30 days. Because of this 2-to-1 ratio, the inner planet goes around twice for each orbit of the outer one: They gravitationally shepherd one another to maintain this synchrony, their elliptical orbits nested and aligned like Russian Matrioshka dolls. These two resonant planets have masses of at least 0.5 and 1.8 the mass of Jupiter, and orbit Gliese 876, a dim red dwarf star only 15 light years from Earth. The team had enough data on the wobble of Gliese 876 two years ago to detect the second planet, but the resonant orbits confounded them. |
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Largest structure in the Universe found?The data are still sketchy, and it is not possible yet to give an actual figure for its mass, but there is evidence for an immense concentration of galaxies over 6.5 billion light years away in the largest known group of quasars (18 of them), possibly the largest structure anywhere in the observable universe. The 11 galaxies found so far in the same supercluster were revealed by light they absorbed from the spectra of even more distant quasars which are located behind the large quasar group. If the concentration of galaxies and quasars is caused by a larger than usual amount of matter in the area, traditional theories of the evolution of the universe have difficulty explaining how gravity could pull extremely massive structures together over such a large distance, in such a relatively short time. Measuring the actual amount of matter connected with quasars and galaxies at such great distances is crucial to find out whether the theories still hold.The massive galaxy concentration is located in Leo, in a region spanning up to two by five degrees. It is contained within a large quasar group, which measures about 600 million light years across. The galaxy cluster is outlined by an unusually large number of quasars - hence the designation "large quasar group". This large quasar group holds 18 quasars in a swath of space roughly a half billion light years across. Normally, only about two to three quasars would be expected in a region this size if there were no galaxy cluster present. And in addition to the quasars, a large number of clouds of gas in the same area have now been found, which are thought to originate in the haloes surrounding galaxies. Those galaxies themselves are faint and have not yet been directly seen, but magnesium atoms in the halo gas of the galaxies absorb light coming from quasars behind the cluster. So far, 11 such faint absorber galaxies have also been found in the same space as the large group of quasars, which is nearly three times more than expected. |
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A "pipeline" of matter between colliding galaxieshas been imaged with the HST: Although astronomers have taken many stunning pictures of galaxies slamming into each other, the new image represents the clearest view of how some interacting galaxies dump material onto their companions. The "pipeline" begins in NGC 1410, crosses over 20,000 light-years of intergalactic space, and wraps around NGC 1409 like a ribbon around a package. Scientists believe that the tussle between these compact galaxies somehow created the pipeline, but they're not certain why NGC 1409 was the one to begin gravitationally siphoning material from its partner. And it's a puzzle why the galaxy is seemingly unaware that it is gobbling up a steady flow of material. A stream of matter funneling into the galaxy should have fueled a spate of star birth, but that didn't happen.It's estimated that NGC 1409 has consumed only about a million solar masses of gas and dust, which is not enough material to spawn star-forming regions like those seen in our Milky Way. The glancing blow between the galaxies was enough, however, to toss stars deep into space and ignite a rash of star birth in NGC 1410: The arms of NGC 1410, an active, gas-rich spiral galaxy classified as a Seyfert, are awash in blue, the signature color of star-forming regions. The bar of material bisecting the center of NGC 1409 also is a typical byproduct of galaxy collisions. |
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Molecular hydrogen found in circumstellar disksIn data from the infrared satellite ISO, a key ingredient for planet making, has been discovered in the faint 'debris disks' that surround three nearby stars, aged 8 to 30 million years: the gas molecular hydrogen. That's relevant because current theories about the formation of giant planets were built on the assumption that the gas was not present in these older disks observed by ISO - these models will now have to be reviewed. They said, for instance, that Jupiter-like planets had to form in just a few million years, but the ISO result implies that the process can take up to 20 million years.This sheds new light on the theories describing how giant gas-rich planets form. There are basically two models: According to the first there are 'instabilities' due to the piling up of material, triggering the collapse of part of the disk and the quick building up of the planets. The second model says that a small 'Earth-like' core is formed first, and then the lighter material in the disk, the gas, is attracted by gravity. In this second model planet formation takes longer than just a few million years. The ISO results imply that it cannot be ruled out: You don't need to make giant planets that quickly. (Thi & al., Nature of Jan. 4, p. 61-3 + Lissauer, ibid. p. 23-4) |
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Stardust's vision has cleared to almost normal!After a few months of foggy vision, NASA's Stardust mission team has improved the spacecraft's navigation-camera resolution to nearly normal, just as Stardust is preparing to make a close flyby of the Earth on Jan. 15 at 11:20 UTC. By heating the camera's optical path, the Stardust team was able to help its nearsighted spacecraft boil away contaminants that had been deposited on optical surfaces. One year ago, the imaging team took pictures of a small lamp inside the optical path of the camera. Apparent contamination of the navigation-camera prevented a clear test-image of the squiggly line of the lamp's filament, and the lens seemed to be covered with a veil of light-scattering material that produced a blurry image.The team concluded that the contamination might have been released with gases escaping from the spacecraft after its launch, and that heating the optical path of the camera might evaporate the contaminant covering the camera lens. After a series of heating cycles, they retested the camera by taking more pictures of the lamp. Pictures taken after the heating revealed that the zigzag line of the lamp's filament was visible again. Images of stars taken by the camera are also clearer. The team estimates the camera can now photograph stars two magnitudes better. The navigation camera has detected stars as faint as 9th mag., which should allow the spacecraft to perform its final navigation maneuvers during approach to the comet nearly at the time originally planned. |
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3 finalists for new Discovery missionAt the end of this year one of the following 3 proposals - just downselected from 26 entries - will be chosen under NASA's Discovery program for a launch in 2005 or 2006, with a total cost of at most $299 million:
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ISS UpdateAtlantis is now on the pad, with preparations under way for the Jan. 19 launch of the U.S. lab module "Destiny." Status Report # 2, 1/2001 plus a Boeing Press Release on Destiny.Coverage of Jan. 12: FT. Jan. 11: AvNow, FT. Jan. 10: SlashDot, SC, FT. Jan. 9: FT. Jan. 8: Interfax. Jan. 6: SC. Jan. 5: SN. Jan. 4: Discovery, CNN. Jan. 3: SN. |
The formal decision to dump Mir has been made by the Russian government
on Dec. 30 - the final Progress will launch on Jan. 18, an emergency crew is
training for possible problems, and a special commission will oversee the deorbiting:
MirNews
(earlier long
report),
AFP
(
earlier),
SC
(earlier,
still earlier),
Interfax,
BBC,
AP
[FT],
SPIEGEL,
RP.
Former Challenger commission chair Rogers dead - William P. Rogers, who was also attorney general and secretary of state, was 87: AP. |
Saturn: 30, Jupiter: 28 moons!That's the latest tally after 2 more Saturn and ten (!) more tiny Jupiter moons (of under 10 km size) have been discovered in recent weeks: MPEC # 2001 - A28 & A29 plus IAUC # 7555 and MPEC # 2000 - Y33 & Y13, a U HI Press Release and coverage by SN, CNN, Discovery, SC.No new pictures from Cassini have been released in the first 2 weeks of the new year, but perhaps the spacecraft and its handlers are just too busy: Status Report. Meanwhile, more info on the joint Cassini/HST observations and GAVRT. Super-Kuiperoid becomes asteroid # 20 000The bookkeepers of minor planets were not allowed to give Pluto the asteroid number 10,000, but now the 2nd largest Kuiper Belt Object after Pluto (formerly known as 2000 WR106; see last Update small items) has been assigned the 20,000: IAU List.A molecular cloud on the verge of collapseis the famous Bok globule Barnard 68 - the cloud is obviously in a temporary state of near-equilibrium, where the inward force of gravity caused by its mass more or less balances that of the outward pressure due to its temperature, but this situation may not last long: ESO Press Release.Young galaxy surrounded by material needed to make starsThe Very Large Array (VLA) radio telescope has discovered a massive reservoir of cold gas from which a primeval galaxy formed its first stars: paper by Papadopoulos & al., NRAO Press Release.168 young stars found near an Orion star forming complex during a survey in Venezuela: Yale Press Release [EA, CV]. Hubble-X, one of the most active star-forming regions within galaxy NGC 6822: HST Heritage Image. 2nd Shenzhou test flight under wayChina launched an unmanned test flight early on Jan. 10, the second in a series expected to lead to a first manned space voyage as early as next year: SD (other story), SC ( earlier), YelloBrix, SN, AP, BBC, AFP, SPIEGEL and pictures. This all makes no sense, Western experts say: AFP.Cyclon loss explained - it likely was caused by a malfunction of the vehicle's third-stage control system: Space.com. Almost-launched SeaLaunch rocket needs engine replaced after a dramatic abort: Status, AvNow, SpaceRef. Arianespace reports a loss for 2000, red figures for the first time ever: AFP, AvNow, SN. |
Oldest rock suggests hospitable young EarthThe oldest known terrestrial rock is a tiny 4.4-billion-year-old zircon - and it's oxygen isotope ratio suggests that early Earth was not an ocean of magma, but cool enough for water, continents, and conditions that could have supported life: NSF, U Wisc. and UCLA Press Releases, coverage by NYT, AP, BBC, SC, SPIEGEL. What is driving plate tectonics? Stanford Press Release.Debris of ancient galaxieshas been found in the halo of the Milky Way - the remains of small galaxies that were torn apart by its gravity, isolated by a survey of RR Lyr stars: Yale Press Release. Galactic "fossils" are also tracked by the 2dF Old Stellar Population Survey: JHU Press Release [SR, EA], coverage by CNN, SN.Completely dark galaxiesmay outnumber the familiar kind populated by shining stars and gas, perhaps by as many as 100 to 1, says a bold prediction: RAS Press Release, BBC, Space.com.It's MACHOs after all in our own galactic halo which cause most of the microlensing events observed over the past years, says a new, complicated study - has the baryonic dark matter been nailed down now? LLNL Press Release [EA]. The source of mysterious lithium in red giant starsis an unusual mixing process - the lithium has been produced within the stars themselves, perhaps via radioactive decay of the unstable isotope beryllium-7: NOAO Press Release.Abell 39, a particularly spherical planetary nebula, will make measurements of the chemical composition easier - though only for the next generation of telescopes: NOAO Press Release. Chandra observations of the Cat's Eye Nebula in X-rays raise questions about the physics of planetary nebulae: Press Release, BBC, APOD, CNN. Calibrating EO-1 in an Aussie salt lakeA team of scientists has just spent a week in a huge barren salt lake in Australia's interior helping to test a new NASA satellite - the novel Hyperion imager of EO-1 needs careful calibration: CSIRO Press Release [SR].
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Compiled and written by Daniel Fischer
(send me a mail to dfischer@astro.uni-bonn.de!), Skyweek