2006
Astronomy 322
NON-OPTICAL ASTRONOMY
M, W, F at 10: 30 a.m.
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 infrared and
X-ray astronomy, but also including some of the following, depending on class
interest: neutrino, cosmic ray, gravitational wave, and ultraviolet astronomy. Prerequisites: Astronomy 206b.
General Description
This course surveys the methods and the results of several branches of astronomy, in particular at radio, IR 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.
IR astronomy, unlike radio, must be carried out above the atmosphere. It is also plagued by emission from the telescope and filters—emitting as greybodies. WeÕll have a distinguished visitor to describe the newest IR satellite observatory, called Spitzer.
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. WeÕll 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.
As is often true in advanced astronomy courses, there are no Òjust rightÓ 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. There is nothing suitable for IR astronomy. 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.
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 ObservatoryÕs 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'"). IÕll have more to say about homework, and especially group homework projects, in an early lecture.
Bruce Partridge
Observatory, phone 896-1144