Credit: ESA/Hubble & NASA
The contorted object captured by Hubble in this picture is
IRAS 22491-1808, also known as the South America Galaxy. It is an
ultraluminous infrared galaxy (ULIRG) that emits a huge amount of light
at infrared wavelengths. The reason for this intense infrared emission
lies in an episode of strong star formation activity, which was set
off by a collision between two interacting galaxies.
In this image the twisted shape hides a number of
features. In the central region, which is very complex and disturbed,
scientists have been able to distinguish two nuclei, remains of the two
different galaxies that are currently colliding to form a new one.
IRAS 22491-1808 is amongst the most luminous of these types of
galaxies, and is considered to be mid-way through its merging stage.
The centre of this appealing object also shows several
intense star-forming knots which, as seen in the picture, actually
outshine the nuclei in optical wavelengths. To pick out the two merging
nuclei in IRAS 22491-1808, scientists have had to observe it in
infrared wavelengths, where they are more distinct.
Other traces of the galactic collision are the three very
noticeable tails in the image — two linear and one circular. The tail
extending towards the bottom of the image from the main body exhibits a
red clump of star formation at its base.
Source: ESA/Hubble - Space Telescope
