The reflection nebula NGC 1999 in Orion posed for the most recent Hubble Heritage Project image.
NASA and the Hubble Heritage Team (STScI/AURA))
Just a few weeks after astronauts repaired the Hubble Space Telescope in December 1999, astronomers snapped the most detailed picture yet of the reflection nebula NGC 1999. Taken with the telescope's Wide Field and Planetary Camera 2, the image is the latest from the Hubble Heritage Project, which each month releases a compelling image of a new subject or one culled from the Hubble archives.
| The reflection nebula NGC 1999 in Orion posed for the most recent Hubble Heritage Project image. NASA and the Hubble Heritage Team (STScI/AURA)) |
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As its name implies, a reflection nebula does not emit any visible light of its own. Like fog around a street lamp, it shines only because the light from an embedded source reflects off the surrounding dust. NGC 1999 lies about 1,500 light-years from Earth and appears only one degree south of the famous Orion Nebula (M42). This entire region of the Milky Way Galaxy is one where new stars are actively being formed.
NGC 1999 holds a prominent place in astronomical history because astronomers discovered the first Herbig-Haro object immediately adjacent to it. (It lies just outside this new Hubble image.) Mysterious at the time, Herbig-Haro objects are now known to be jets of gas ejected from very young stars.
The bright, recently formed star that lies just to the left of the photo's center illuminates the nebula. Cataloged as V380 Orionis, this star tips the scale at some 3.5 solar masses. It appears white because it has a high surface temperature, which reaches about 10,000 degrees Celsius (18,000 degrees Fahrenheit), nearly twice that of the sun. V380 Orionis is so young that the cloud of material left over from its formation -- the NGC 1999 reflection nebula -- still surrounds it.
The WFPC2 image shows a remarkable jet-black cloud near its center and just to the right of the bright star. Looking a bit like a letter T tilted on its side, the cloud is an example of a Bok globule. These objects, named after the late University of Arizona astronomer Bart Bok, are cold clouds of molecular gas and cosmic dust dense enough to block all of the light coming from beyond. Astronomers think that new stars form inside Bok globules as the dust and molecular gas contract under their own gravity.
3/6/00
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