Colloquium
The Galaxy's Halo
Dr. Robin Shelton
Department of Physics & Astronomy
University of Georgia
Thursday, October 16,
2008, 12:15
p.m.,
SCIC 126
The gas
between the stars in our galaxy fundamentally affects how our galaxy,
the Milky Way, behaves. It provides the material from which
new stars form, absorbs the material cast off of massive stars when
they die, and stores material for the creation of future
stars. Not only does gas permeate the disk, where most of the
galaxy's stars
are found, but it also resides above the disk, in the
halo. Observations reveal that much of the gas in the halo is
extremely hot
(T ~ a million degrees K). Heating large quantities of gas to
such high temperatures requires extremely large energy
sources. Thus, the hot gas that we see now can be
treated as a tracer of extremely energetic events that occurred in our
galaxy's past. It is a window into the Milky Way's
history and behavior. However, our galaxy is capable of creating
hot gas by many means, so astronomers must determine which types of
events heated the gas in the halo. The most well known
explanation is that clustered supernova explosions energize gas in the
disk and that this gas later expands into the halo. However,
infalling intergalactic gas could also be important. In
this talk, I will discuss the observed characteristics of the hot gas
in the halo and will relate these characteristics to the types of
events that may have heated the gas in our galaxy.
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