New
telescope images reveal a previously unknown rich cluster of stars in the inner parts of the Milky Way.
This closely-packed
star family, consisting of about 100,000 stars and located some 30,000 light-years
away, was spotted with the European Southern Observatory's New Technology
Telescope (NTT) at La Silla, Chile.
The
discovery was part of a large-scale search for globular clusters in the
Galactic Plane--a slice of space in which the star-rich disk of our galaxy lies. Globular
clusters are gravity-bound groups of stars with spherical symmetry created
at roughly the same time and from the same material. Typically, they are
shrouded by dense clouds of gas and dust in the Milky Way, so infrared
radiation is the only mechanism to locate such features.
After
locating about a dozen clusters with the near-infrared Two Micron All Sky
Survey (2MASS), astronomers took new images through three different near-infrared
filters--producing images that are 10 times deeper and much more precise than
the 2MASS images.
"It
has been estimated that the region close to the Galactic Center might contain
about 10 so-far unknown globular clusters, and we have started a large campaign
to unveil and characterize them," said study team member Helmut Meusinger
of the Thüringer Landessternwarte, an observatory in Germany.
Combing
through the new images, the astronomers found FSR 1735, most likely a new
globular cluster, which previously appeared to be just a cloud of dust and gas.
"The
unique images we have obtained reveal that the nebulous appearance of the cluster in
previous images is, in fact, due to a large number of faint stars," said study
team member Dirk Froebrich of the University of Kent. "The images show a
beautiful, rich and circular accumulation of stars."
FSR 1735, with
a mass estimated to be 65,000 times that of the Sun, is about seven light-years wide. Such
globular clusters, 150 of which are known in our galaxy, are some of the oldest
objects in it and witnesses
to the earliest events of the Universe.
"We
believe today that galaxy
collisions, galaxy
cannibalism, as well as galaxy
mergers, leave their imprint in the globular cluster population of any
given galaxy," Froebrich said. "Thus, when investigating globular clusters, we
hope to be able to use them as an acid test for our understanding of the formation
and evolution of galaxies."
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