Galaxy Cluster Has Two 'Tails' to Tell
February 5, 2010
Two spectacular tails of X-ray emission have been seen trailing behind
a galaxy using the Chandra X-ray Observatory. A composite image of the
galaxy cluster Abell 3627 shows X-rays from Chandra in blue, optical
emission in yellow and emission from hydrogen light -- known to
astronomers as 'H-alpha' -- in red. The optical and H-alpha data were
obtained with the Southern Astrophysical Research (SOAR) Telescope in
Chile. At the front of the tail is the galaxy ESO 137-001. The brighter
of the two tails has been seen before and extends for about 260,000
light years. The detection of the second, fainter tail, however, was a
surprise to the scientists. The X-ray tails were created when cool gas
from ESO 137-001 (with a temperature of about ten degrees above
absolute zero) was stripped by hot gas (about 100 million degrees) as
it travels towards the center of the galaxy cluster Abell 3627. What
astronomers observe with Chandra is essentially the evaporation of the
cold gas, which glows at a temperature of about 10 million degrees.
Evidence of gas with temperatures between 100 and 1,000 degrees Kelvin
in the tail was also found with the Spitzer Space Telescope. Galaxy
clusters are collections of hundreds or even thousands of galaxies held
together by gravity that are enveloped in hot gas. The two-pronged tail
in this system may have formed because gas has been stripped from the
two major spiral arms in ESO 137-001. The stripping of gas is thought
to have a significant effect on galaxy evolution, removing cold gas
from the galaxy, shutting down the formation of new stars in the
galaxy, and changing the appearance of inner spiral arms and bulges
because of the effects of star formation. Image Credits: X-ray:
NASA/CXC/UVa/M. Sun et al; H-alpha/Optical:
SOAR/MSU/NOAO/UNC/CNPq-Brazil/M.Sun et al.
Posted by Prateek Tripathi.
