AST 320 - The Interstellar Medium, Spring 2009
Recommended texts:
"The Interstellar Medium" by James Lequeux. "The Physics and Chemistry of the Interstellar Medium" by A. G. G. M. Tielens.However, both books are very detailed for an introductory course. I will often use chapters from additional textbooks and/or journal articles. The reading list will be provided for each class, as well as lecture notes. For details see course syllabus.
Course Motivation:
The interstellar medium (ISM) is the matter which occupies the enormous volume between stars. The ISM consists
of gas and dust particles, permeated by magnetic fields and bathed by energetic cosmic rays (energetic protons,
electrons and gamma rays). Why is the ISM important? Stars are born from the ISM, and they die and return matter
to the ISM at the end of their life. Properties and evolution of galaxies in general are entirely a result of the
delicate interplay between the stars and the ISM. Therefore, as the ISM carries embedded signatures of these
complex and delicate interactions, it can tell us the story about the past, present and future of any galaxy.
The interstellar gas exists in the ISM with an extremely wide range of physical properties, commonly grouped into the following five different phases: the molecular medium, the cold neutral medium, the warm neutral medium, the warm ionized medium, and the hot ionized medium. The energy balance in the ISM, responsible for the existence of different interstellar phases, is mostly determined by the cooling and heating processes on a microscopic level.
The ISM is full of beautiful structures with sizes spanning over a huge range of scales. Here are a few examples:
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| Bubble RCW79 (GLIMPSE project) | Star-forming region RCW49 (GLIMPSE project) |
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| N44 Superbubble (APOD) | The Small Magellanic Cloud in neutral hydrogen |
Brief Course Description:
In this course, we will describe various flavors of the ISM, consider physical processes occurring in the ISM, investigate some cool examples of the ISM structure, and try to blend all this together into a coherent big picture. During this journey, we will mainly focus on the Galaxy, but will touch upon a few other nearby galaxies like the Magellanic Clouds. The course will especially emphasize the observational ways used to study the diverse ISM. There will be a few homework assignments, and a small project that will involve using real astronomical data.