The NASA/ESA Hubble Space Telescope has captured a new view of the dwarf
galaxy UGC 5497, which looks a bit like salt sprinkled on black velvet
in the image.
The object is a compact blue dwarf galaxy that is infused with newly
formed clusters of stars. The bright, blue stars that arise in these
clusters help to give the galaxy an overall bluish appearance that lasts
for several million years until these fast-burning stars explode as
supernovae.
UGC 5497 is considered part of the M 81 group of galaxies, which is
located about 12 million light-years away in the constellation Ursa
Major (The Great Bear). UGC 5497 turned up in a ground-based telescope
survey back in 2008 looking for new dwarf galaxy candidates associated
with Messier 81.
According to the leading cosmological theory of galaxy formation,
called Lambda Cold Dark Matter, there should be far more satellite dwarf
galaxies associated with big galaxies like the Milky Way and Messier 81
than are currently known. Finding previously overlooked objects such as
this one has helped cut into the expected tally -- but only by a small
amount.
Astrophysicists therefore remain puzzled over the so-called "missing satellite" problem.
The field of view in this image, which is a combination of visible
and infrared exposures from Hubble's Advanced Camera for Surveys, is
approximately 3.4 by 3.4 arcminutes.
http://www.sciencedaily.com/releases/2012/06/120619105101.htm
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