October 19: Subrahmanyan Chandrasekhar

Subrahmanyan Chandrasekhar

October 19, 1910 – August 21, 1995

Subrahmanyan Chandrasekhar was an Indian American astrophysicist. He was a Nobel laureate in physics along with William Alfred Fowler for their work in the theoretical structure and evolution of stars. He was the nephew of Indian Nobel Laureate Sir C. V. Raman.

Chandrasekhar served on the University of Chicago faculty from 1937 until his death in 1995 at the age of 84. He became a naturalized citizen of the United States in 1953.

Chandrasekhar (Chandra) was born in Lahore, India (present day Pakistan). Chandra was awarded a Government of India scholarship to pursue graduate studies at the University of Cambridge, where he was admitted to Trinity College and became a research student of Professor R. H. Fowler. On the advice of Prof. P. A. M. Dirac, as part of his graduate studies, Chandra spent a year at the Institut for Teoretisk Fysik in Copenhagen, where he met Prof. Niels Bohr.

In January 1937, Chandrasekhar was recruited to the University of Chicago faculty as Assistant Professor by Dr. Otto Struve and President Robert Maynard Hutchins. He was to remain at the university for his entire career, becoming Morton D. Hull Distinguished Service Professor of Theoretical Astrophysics in 1952 and attaining emeritus status in 1985.

Chandrasekhar developed a style of working continuously in one specific area of physics for a number of years; consequently, his working life can be divided into distinct periods. He studied stellar structure, including the theory of white dwarfs, during the years 1929 to 1939, and subsequently focused on stellar dynamics from 1939 to 1943. Next, he concentrated on the theory of radiative transfer and the quantum theory of the negative ion of hydrogen from 1943 to 1950. This was followed by sustained work on hydrodynamic and hydromagnetic stability from 1950 to 1961. In the 1960s, he studied the equilibrium and the stability of ellipsoidal figures of equilibrium, but also general relativity. During the period, 1971 to 1983 he studied the mathematical theory of black holes, and, finally, during the late 80s, he worked on the theory of colliding gravitational waves.

From 1952 to 1971 Chandrasekhar was editor of the Astrophysical Journal.

During the years 1990 to 1995, Chandrasekhar worked on a project devoted to explaining the detailed geometric arguments in Sir Isaac Newton's Philosophiae Naturalis Principia Mathematica using the language and methods of ordinary calculus. The effort resulted in the book Newton's Principia for the Common Reader, published in 1995. Chandrasekhar was an honorary member of the International Academy of Science.

Chandrasekhar's most famous success was the astrophysical Chandrasekhar limit. The limit describes the maximum mass of a white dwarf star, ~1.44 solar masses, or equivalently, the minimum mass, above which a star will ultimately collapse into a neutron star or black hole (following a supernova). The limit was first calculated by Chandrasekhar in 1930 during his maiden voyage from India to Cambridge, England for his graduate studies.

In 1999, NASA named the third of its four "Great Observatories'" after Chandrasekhar. The Chandra X-ray Observatory was launched and deployed by Space Shuttle Columbia on July 23, 1999.

The asteroid 1958 Chandra is also named after Chandrasekhar.

Chandrasekhar was the mathematics professor of the renowned American astronomer Carl Sagan at the University of Chicago. In his book The Demon-Haunted World Sagan wrote "I discovered what true mathematical elegance is from Subrahmanyan Chandrasekhar."