WASHINGTON: HUBBLE LOOKS INTO TERZAN 7
February 17, 2014 Monday
National Aeronautics and Space Administration, The Government of USA
has issued the following news release:
Named after its discoverer, the French-Armenian astronomer Agop
Terzan, this is the globular cluster Terzan 7 -- a densely packed
ball of stars bound together by gravity. It lies just over 75,000
light-years away from us on the other side of our galaxy, the Milky
Way. It is a peculiar cluster, quite unlike others we observe, making
it an intriguing object of study for astronomers.
Evidence shows that Terzan 7 used to belong to a small galaxy called
the Sagittarius Dwarf Galaxy, a mini-galaxy discovered in 1994. This
galaxy is currently colliding with, and being absorbed by, the Milky
Way, which is a monster in size when compared to this tiny one. It
seems that this cluster has already been kidnapped from its former
home and now is part of our own galaxy.
Astronomers recently discovered that all the stars in Terzan 7 were
born at around the same time, and are about eight billion years old.
This is unusually young for such a cluster. The shared birthday is
another uncommon property; a large number of globular clusters, both in
the Milky Way and in other galaxies, seem to have at least two clearly
differentiated generations of stars that were born at different times.
Some explanations suggest that there is something different about
clusters that form within dwarf galaxies, giving them a different
composition. Others suggest that clusters like Terzan 7 only have
enough material to form one batch of stars, or that perhaps its
youthfulness has prevented it from yet forming another generation.
For more information please visit: http://www.nasa.gov