Subrahmanyan Chandrasekhar (born October 19, 1910,Lahore, India [now in Pakistan]—died August 21, 1995,Chicago,Illinois, U.S.) was an Indian-born Americanastrophysicist who, withWilliam A. Fowler, won the 1983Nobel Prize for Physics for key discoveries that led to the currently accepted theory on the later evolutionary stages of massivestars.

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

By the early 1930s, scientists had concluded that, after converting all of theirhydrogen tohelium, stars lose energy and contract under the influence of their owngravity. These stars, known aswhite dwarf stars, contract to about the size ofEarth, and theelectrons and nuclei of theirconstituentatoms are compressed to a state of extremely high density. Chandrasekhar determined what is known as theChandrasekhar limit—that astar having amass more than 1.44 times that of theSun does not form a white dwarf but instead continues to collapse, blows off its gaseous envelope in asupernova explosion, and becomes aneutron star. An even more massive star continues to collapse and becomes ablack hole. These calculations contributed to the eventual understanding of supernovas, neutron stars, and black holes. Chandrasekhar came up with the idea for a limit on his voyage toEngland in 1930. However, his ideas met strong opposition, particularly from English astronomerArthur Eddington, and took years to be generally accepted.

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

Chandrasekhar was awarded the Gold Medal of theRoyal Astronomical Society in 1953, the Royal Medal of theRoyal Society in 1962, and theCopley Medal of the Royal Society in 1984. His other books includedAn Introduction to the Study of Stellar Structure (1939),Principles of Stellar Dynamics (1942),Radiative Transfer (1950),Hydrodynamic and Hydromagnetic Stability (1961),Truth and Beauty: Aesthetics and Motivations in Science (1987), andNewton’s Principia for the Common Reader (1995).