Chandrasekhar’s book An Introduction to the Study

of Stellar Structure

PETER P EGGLETON

Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, USA

E-mail: eggleton1@llnl.gov

Abstract. 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 LastWord 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?’

Keywords. S Chandrasekhar; stellar structure; thermodynamics.

PACS Nos 97.10.Cv; 64.70.qd; 67.30.ef