The matter between the stars - the interstellar medium - manifests
itself in many interesting and unexpected ways, and, as the detritus of
stars, its properties and behavior hold clues to the history and future
evolution of both stars and the galaxies that contain them. Stars are
accompanied by diffuse matter all through their lifetimes, from their
birthplaces in dense molecular clouds, to the stellar winds they eject
with varying ferocity as they evolve, to their final fates as they
shed their outer layers, whether as planetary nebulae or dazzling
supernovae. As these processes go on, they enrich the interstellar
medium with the products of the stars' nuclear fusion. The existence
of life on Earth is eloquent evidence of this chemical
enrichment.
In this course we will study the interstellar medium in its various
forms. We will discuss many of the physical mechanisms that produce
the radiation we observe from diffuse matter, including radiative
ionization and recombination, collisional excitation of "forbidden"
lines, collisional ionization, and synchrotron radiation. This course
will be observing-intensive. Throughout the
semester students will work in small groups to design, carry
out, analyze, and and critique their own observations of the
interstellar medium using the equipment on our observing deck.
The solar corona has recently been revealed as the connection between the sun and the earth. Observations from the 10 instruments on the Solar and Heliospheric Observatory (SOHO) now aloft are showing the flow of material from the sun to the earth in unprecedented detail. Further, data from the total solar eclipses of 26 February 1998 and 11 August 1999 will be used to study the cause of the heating of the solar corona and will be linked to space observations from SOHO and from the Yohkoh x-ray solar satellite. We discuss theoretical aspects and observational techniques, and will make solar observations. Students will meet weekly with the professor in groups of two or three to discuss readings, solve problems, present short papers, and/or make observations.
We study all aspects of the sun, our nearest star, as we approach the maximum of the sunspot cycle. We discuss the interior, including the neutrino experiment and helioseismology, the photosphere, the chromosphere, the corona, and the solar wind. We discuss the sun as an example of stars in general. We discuss both theoretical aspects and observational techniques, including work at the recent total solar eclipses. We discuss results from current spacecraft, including the Solar and Heliospheric Observatory (SOHO) and the Transition Region and Coronal Explorer (TRACE).
The past decade has seen the birth of "precision cosmology," based on
combined results from Hubble Space Telescope key projects, cosmic
microwave background satellites and ground-based surveys. According to
the derived "concordance model" the universe is 13.7 billion years old
and is currently expanding at a rate of 72 km/sec/megaparsec. The
model also describes a flat, accelerating big-bang universe that
underwent very early inflation and is now dominated by dark energy and
cold dark matter. In this course students will explore the
observations and interpretations that have led to our current
understanding of the universe's history and structure. Topics will
include galaxy structure and evolution, the cosmic microwave
background (e.g., Cosmic Background Observer and Wilkinson Microwave
Anisotropy Probe) distant supernova searches (e.g., High-Z Supernova
Team and Supernova Cosmology Project), galaxy surveys (e.g., Sloan
Digital Sky Survey and 2dF (two-degree field)) as well as theoretical
and supercomputing efforts. Students will read portions of current
texts as well as some more detailed research papers. Astronomy 419T
students will complete additional reading and present papers covering
more advanced topics than 219T
A writing-intensive course.
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