Astronomy and Astrophysics - An Introductory Survey, A lecture series by Prof. G. Srinivasan - Lecture 6 - Interstellar Medium - Molecular Gas

The ratio of intensities suggested rotational temperature of 2.3K, which, of course, has a limited meaning." A remark made by Herzberg on the basis of the observations on the molecular spectra of cyanogen (CN), 24 years before the discovery of Cosmic Microwave Background radiation which, we now know, has that characteristic temperature. ABOUT THE LECTURE Apart from giant clouds of atomic hydrogen, there are also giant clouds of molecular hydrogen in interstellar space. These molecular clouds are the sites of the formation of new stars and hence have a special role in the life cycle of the birth and death of stars. This lecture is devoted primarily to an understanding of the various energy levels of simple diatomic molecules, and the resultant radiation from them. The spatial distribution of giant molecular clouds in our Galaxy, as well as other galaxies, is described. ABOUT THE LECTURE SERIES This lecture series is organized by the Astronomical Society of India as a part of its Golden Jubilee celebrations. Aimed at undergraduate and graduate students, this series of talks by renowned astrophysicist and teacher, Prof G. Srinivasan, starts from the first principles of Physics and builds up the subject rigorously to the present state of our understanding. Series website: https://astron-soc.in/srini-ana The website hosts a question bank as well as a list of suggested reading for each lecture (prepared by Dr. Sushan Konar) ABOUT THE SPEAKER Professor G. Srinivasan In a research career spanning more than five decades, his interests have spanned many aspects of physics and astrophysics. He is a passionate teacher and has authored two outstanding Astronomy texts titled ‘What Are The Stars?’ and ‘Can Stars Find Peace?’ He is a Past President of the Astronomical Society of India, and a Past President of the Division on Space and High Energy Astrophysics of the International Astronomical Union. In his distinguished career he has worked at the University of Chicago, USA; the IBM Research Laboratory in Zurich, Switzerland; Chalmers University of Technology, Goteborg, Sweden; the Cavendish Laboratory, University of Cambridge, England and the Raman Research Institute, Bengaluru Follow us on social media at https://twitter.com/asipoec https://www.facebook.com/asi.poec/ This series is also supported by the IAU OAE Centre in India https://twitter.com/astro4edu_India https://www.facebook.com/OAE-Center-India-105698322030674