Chandrasekhar, Subrahmanyan

born Oct. 19, 1910, Lahore, India

died Aug. 21, 1995, Chicago, Ill., U.S.

Indian-born U.S. astrophysicist.

He left the University of Cambridge to join the staff of the University of Chicago in 1938. He determined that, following its red giant phase, a star with a remaining mass greater than 1.4 times that of the Sun (the Chandrasekhar limit) collapses and becomes a neutron star during a supernova explosion. Stellar remnants more massive than about three solar masses collapse even further to become black holes. He shared a 1983 Nobel Prize with William A. Fowler.

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▪ 1996

      Indian-born U.S. astrophysicist (b. Oct. 19, 1910, Lahore, India [now in Pakistan]—d. Aug. 21, 1995, Chicago, Ill.), shared with William A. Fowler the 1983 Nobel Prize for Physics for his theory on the later stages of stellar evolution, work that subsequently led to the discovery of neutron stars and black holes. This theory, which contradicted the then current belief that all dying stars end their lives by contracting into extremely dense white dwarfs, predicted that stars with masses greater than 1.4 times that of the Sun (the Chandrasekhar limit, eventually revised to 1.2 solar masses) would collapse into objects smaller and denser than white dwarfs—neutron stars and black holes. Chandrasekhar received (1930) a B.A. from Presidency College, University of Madras, India, and completed (1933) his doctorate in theoretical physics at the University of Cambridge. In 1937 he joined the University of Chicago at Yerkes Observatory, Williams Bay, Wis., becoming (1952) the Morton D. Hull distinguished service professor of astrophysics, a post he held until 1986, when he became professor emeritus. During this time the focus of his research shifted among such topics as stellar structure, the transfer of energy in stellar atmospheres, and black holes. From 1952 to 1971 he served as editor of the Astrophysical Journal, which became the national journal of the American Astronomical Society. The recipient of numerous awards, including the 1953 Gold Medal of the Royal Astronomical Society, Chandrasekhar was also the author of 10 books; his last, Newton's "Principia" for the Common Reader, was published in 1995.

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▪ American astronomer

born October 19, 1910, Lahore, India [now in Pakistan]

died August 21, 1995, Chicago, Illinois, U.S.

 Indian-born American astrophysicist who, with William A. Fowler (Fowler, William A.), won the 1983 Nobel Prize for Physics for key discoveries that led to the currently accepted theory on the later evolutionary stages of massive stars.

      Chandrasekhar was the nephew of Sir Chandrasekhara Venkata Raman, who won the Nobel Prize for Physics in 1930. Chandrasekhar was educated at Presidency College, at the University of Madras, and at Trinity College, Cambridge. From 1933 to 1936 he held a position at Trinity.

      By the early 1930s, scientists had concluded that, after converting all of their hydrogen to helium, stars lose energy and contract under the influence of their own gravity. These stars, known as white dwarf stars, contract to about the size of the Earth, and the electrons and nuclei of their constituent atoms are compressed to a state of extremely high density. Chandrasekhar determined what is known as the Chandrasekhar limit—that a star having a mass more than 1.44 times that of the Sun does not form a white dwarf but instead continues to collapse, blows off its gaseous envelope in a supernova explosion, and becomes a neutron star. An even more massive star continues to collapse and becomes a black hole. These calculations contributed to the eventual understanding of supernovas, neutron stars, and black holes.

      Chandrasekhar joined the staff of the University of Chicago, rising from assistant professor of astrophysics (1938) to Morton D. Hull distinguished service professor of astrophysics (1952), and became a U.S. citizen in 1953. He did important work on energy transfer by radiation in stellar atmospheres and convection on the solar surface. He also attempted to develop the mathematical theory of black holes, describing his work in The Mathematical Theory of Black Holes (1983).

      Chandrasekhar was awarded the Gold Medal of the Royal Astronomical Society in 1953 and the Royal Medal of the Royal Society in 1962. His other books include An Introduction to the Study of Stellar Structure (1939), Principles of Stellar Dynamics (1942), Radiative Transfer (1950), Hydrodynamic and Hydromagnetic Stability (1961), and Truth and Beauty: Aesthetics and Motivations in Science (1987).

Additional Reading

Kameshwar C. Wali, Chandra: A Biography of S. Chandrasekhar (1991), describes his life and career.

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