Astronomy 322
NON-OPTICAL ASTRONOMY
Catalog Description
Introduction to the basic techniques of radio astronomy, to the various emission
mechanisms at radio wavelengths, and to radio studies of astronomical phenomena.
Some discussion of other non-optical branches of astronomy, especially X-ray
astronomy, but also including some of the following, depending on class interest:
neutrino, cosmic ray, gravitational wave, infrared, and ultraviolet astronomy.
Prerequisites: Astronomy 206b.
Offered in 2004-05 and alternate years.
General Description
This course surveys the methods and the results of several branches of astronomy,
in particular at radio and X-ray wavelengths. Since I am an observer, we will
emphasize observational techniques and results, rather than theory.
After a very brief introduction (astronomical coordinates; atmospheric opacity;
blackbody radiation), we'll turn to radio astronomy, which we will study for
the first 8 weeks or so.
Our study of radio astronomy will begin with the nature and operation of receivers
at radio frequencies, and the problem of noise, a key issue in radio astronomy.
Then we turn to diffraction and the constraints it sets on angular resolution.
We investigate beam patterns of radio telescopes.
To achieve higher angular resolution—now better than that realized by
optical instruments—radio astronomers use interferometers. We'll study
interferometers and aperture synthesis next, with special emphasis on the
Very Large Array (VLA), which the class will have a chance to use.
Then several weeks of the course will deal with some of the discoveries of
radio astronomy. We'll begin by looking at various non-thermal processes which
produce radio frequency emission, then at line emission from both atoms and
molecules. Along the way, I'll talk about ways in which radio astronomy has
revealed the properties of a variety of astronomical sources—planets,
collapsed stars like neutron stars, the interstellar medium, galaxies, quasars
and the early Universe.
X-ray astronomy differs from optical and radio astronomy in many ways: each
photon is precious; X-ray observations cannot be done from the ground; and
optical elements are very hard to make. We'll survey X-ray techniques, look
at characteristic X-ray sources in the Galaxy and beyond it, then investigate
the connections between radio and X-ray astronomy. There are many, since both
branches of the field are particularly useful for studying very energetic
astrophysical processes. We’ll spend ~4 weeks on X-ray astronomy.
In the final few weeks, we'll look more briefly at other more exotic (and
more recent) branches of astronomy, such as neutrino and gravity wave astronomy.
I will also ask each of you to choose one other branch of non-optical
astronomy, then present both a brief paper and a ~20 min. talk on it.
Reading
As is often true in advanced astronomy courses, there are no “just right”
textbooks available for this course. In the first half, we will make heavy
use of An Introduction to Radio Astronomy by B. F. Burke and F. Graham-Smith.
For X-ray astronomy, we will rely on Exploring the X-ray Universe by
Charles and Seward (I'll ask you to share copies). Because astronomy books
are so costly, I will ask you to buy only the first of these two books. We
will also occasionally use a couple of other texts and monographs. We will
also read some articles from scientific journals, such as The Astrophysical
Journal. I'll help decipher the latter. All reading material will be placed
on reserve in the Observatory library.
Other Details
Given that there is no truly satisfactory textbook for 322, attendance at
the lectures is important. Come to lectures prepared; do the required reading
carefully and in advance. Attendance at talks given by your fellow students
(see above) is mandatory.
I am trying to make arrangements to take the entire 322 class out to New Mexico
to visit and to use the National Radio Astronomy Observatory’s VLA (Very
Large Array). More on these plans later.
I currently plan to give three, equally weighted, open book tests and no cumulative
final (instead, the third test will be during finals week). There will also
be (almost) weekly problem sets, which will be graded. Finally, I will ask
each of you to do an independent project following up a branch of non-optical
astronomy not covered in lecture.
For grading purposes, each of the three tests will count for 15-20%, the homework
~30%, and the independent project ~15%.
A final word on the homework—you may use any source you find useful,
but you must acknowledge it (e.g.—"Problem 7 solved with help from
p. 70 of J. D. Kraus's Radio Astronomy"). Likewise, if you work
with other students, that collaboration must be acknowledged (e.g.—"John
Smith actually solved most of problem 3 while I watched 'The Simpsons'").
I’ll have more to say about homework, and especially group homework projects,
in an early lecture.
Bruce Partridge
Observatory, phone 896-1144
bpartrid@haverford.edu
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updated 9/1/04