HUBBLE CAPTURES COLLISION OF GASES NEAR DYING STAR
[哈勃捕捉到一死亡恒星附近的气体碰撞]
This colorful image from the Hubble Space Telescope shows the
collision of two gases near a dying star. Astronomers have dubbed
the tadpole-like objects in the upper right-hand corner "cometary
knots" because their glowing heads and gossamer tails resemble
comets. Although astronomers have seen gaseous knots through
ground-based telescopes, they have never seen so many in a single
nebula.
Hubble captured thousands of these knots from a doomed star in the
Helix nebula, the closest planetary nebula to Earth at 450 light-years
away in the constellation Aquarius. Each gaseous head is at least
twice the size of our solar system; each tail stretches 100 billion
miles, about 1,000 times the Earth's distance to the Sun. The most
visible gaseous fragments lie along the inner edge of the star's ring,
trillions of miles from the star at its center. The comet-like tails
form a radial pattern around the star like the spokes on a wagon
wheel. Astronomers have seen the spoke pattern using ground-based
telescopes, but Hubble reveals for the first time the sources of
these objects.
Astronomers theorize that the gaseous knots are the results of a
collision between gases. The doomed star spews the hot gas from
its surface, which collides with the cooler gas that it had ejected
10,000 years before. The crash fragments the smooth cloud
surrounding the star into smaller, denser finger-like droplets, like
dripping paint. Astronomers expect the gaseous knots, each several
billion miles across, to eventually dissipate into the cold blackness
of interstellar space.
This image was taken in August, 1994 with Hubble's Wide Field
Planetary Camera 2. The red light depicts nitrogen emission
([NII] 6584A); green, hydrogen (H-alpha, 6563A); and blue,
oxygen (5007A).
Credit: Robert O'Dell, Kerry P. Handron (Rice University,
Houston, Texas) and NASA
Image files in GIF and JPEG format and captions may be accessed
on Internet via anonymous ftp from oposite.stsci.edu in /pubinfo.
Higher resolution digital versions (300dpi JPEG) of the release
photographs will be available temporarily in /pubinfo/hrtemp:
96-13a.jpg (color) and 96-13aBW.jpg (black/white).
