Chandrasekhar’s book An Introduction to the Study of Stellar Structure

• Published in: Pramāṇa Vol. 77; no. 1; pp. 97 - 105
• Main Author: EGGLETON, PETER P
• Format: Journal Article
• Language: English
• Published: India Springer-Verlag 01.07.2011
• Subjects: Astronomy; Astrophysics and Astroparticles; Observations and Techniques; Physics; Physics and Astronomy; thermodynamics; 64.70.qd; S Chandrasekhar; stellar structure; 97.10.cv; 67.30.ef
• ISSN: 0304-4289; 0973-7111
• DOI: 10.1007/s12043-011-0114-3

For me, and for many astrophysicists of my generation, Chandrasekhar’s book An Introduction to the Study of Stellar Structure was very important. I could not have done my PhD (1962–1965) without it. Much more recently (1998) I realized that I could not have written my lecture course on thermodynamics and statistical mechanics without much of it, particularly the first chapter. I shall present anecdotal evidence that the influence of his discussion on the second law of thermodynamics has been important not just for astrophysics but for a much wider range of physics. Chandrasekhar’s discussion of polytropes was masterly. Even today polytropes play an important role as an aid for understanding stellar structure. I believe that to the list of analytic solutions of the polytrope only one more has to be added: a curious n  = 5 model of Srivastava (1962). Stellar structure is nowadays a very computationally intensive subject. I shall illustrate this with a couple of topics from my experience with Djehuty , a supercomputer code for modelling stars in 3D. Nevertheless it remains true, I believe, that analytical mathematical entities like polytropes are fundamental as aids for understanding what the computers churn out. How close are we to seeing a book with the title ‘The Last Word on the Study of Stellar Structure’? Not very, although much has been learned in 70 years. I shall discuss a few of the aspects of stellar evolution that are problematic today. I shall discuss a couple of aspects where I believe analysis of ‘piecewise polytropic’ structures sheds light on the question ‘Why do stars become red giants?’