Here is a sampling of current research topics in the department.
Pulsars
These rapidly rotating
neutron stars are dramatic laboratories for extreme physics. They are built of
matter as dense as an atomic nucleu. Their atmospheres contain relativistic,
strongly magnetized plasmas unlike anything which can be duplicated in terrestrial
laboratories. We know why they pulse (they rotate many times each second), but we
don't know why they shine (how do they make coherent radio radiation?)
Plasma astrophysics
Plasmas can be found throughout astrophysics. What we learn from lab and
space plasma can be applied to astrophysical objects. Examples include
the interior of stars, the earth's magnetosphere, the gas between the stars in
our galaxy, the relativistic jets emitted by black holes, and the diffuse
atmosphere in a cluster of galaxies.
Star formation
Stars are born when the core of a dense molecular cloud collapses under
its own self-gravity. We still have much to learn about this process:
how does the collapse occur, how is the material assembled into a star,
what determines the mass of the star,
and how does the star evolve after it is born?
Stellar evolution
After a long life on the main sequence, stars run out of nuclear fuel and
begin to enlarge and cool. Such aging stars may pulsate, lose mass, or even
explode. These different paths depend on the star's mass and on whether it
is isolated or lives in a binary system.
Radio galaxies
Massive black holes sit in the nuclei of many otherwise-normal galaxies.
Accretion onto these black holes drives jets out along the rotation axis.
Radio galaxies are made when these jets run into the surrounding
intergalactic gas.
Clusters of galaxies
These are the largest self-gravitating structures in the universe. In
addition to galaxies, they contain a hot, magnetized gaseous atmosphere,
as well as a large amount of unseen "dark" matter. The cluster
atmospheres -- which can be observed with radio and X-ray telescopes --
are important probes of the underlying dark matter and cosmological
evolution of the cluster.
The interstellar medium
The diffuse gas in a galaxy is the reservoir from which stars are born
and to which stellar mass loss returns.
Its physical state ranges from hot, tenuous "coronal" plasma,
to cold, dense molecular clouds. The interactions between stars and
the different gas phases play critical roles in galaxy evolution.
Dynamics and evolution of nearby galaxies
The structure of a galaxy reveals many facets of the galaxy's origin and
evolution. Dynamical studies allow us to measure the distribution of dark
matter in the galaxy. Comparing observed galactic structure to theoretical
models of galaxy formation allows us to test those models. The internal
dynamics of a galaxy are also sensitive tracers of its past interaction with
other galaxies.
Optical interferometry
This rapidly growing research area will provide the very high resolution
images needed for studying such things as stellar structure and active galactic
nuclei. The instrumentation needed for such studies includes low-noise detectors,
innovative telescope designs, adaptive optics, real-time control software, and
vacuum and cryogenic equipment. These will all be involved in the multi-element
interferometer being developed at
MRO.
The supernova remnant Cas A; radio
image from the (NRAO)
image gallery.
The Hercules cluster of galaxies; image from
V. Andersen,
U. Alabama ,
through APOD
Spiral galaxy NGC 4414; optical
image from Hubble Heritage Team
(HST)
