Subrahmanyan Chandrasekhar October 20, 2009Posted by jcconwell in Astronomers, Astronomy, white dwarf.
Tags: Chandrasekhar, white dwarf
One Hundred years ago, yesterday, October 19, 1910, Subrahmanyan Chandrasekhar was born.
Arguably the greatest astrophysicist of the twentieth century, his name is in every astronomy book. From the upper mass limit of a white dwarf, Chandrasekhar’s limit, to the orbiting Chandra X-ray telescope, he left his mark on the very concepts and vocabulary that physicists and astronomers use today.
Chandrasekhar was the nephew of Sir Chandrasekhara Venkata Raman, who won the Nobel Prize for Physics in 1930. Chandrasekhar was educated 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. Using the new theory of Quantum Mechanics, 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. Later it was found that more massive stars cores collapse blows off its gaseous envelope in a Type II supernova explosion, leaving a neutron star. An even more massive star continues to collapse leaving a black hole. Type Ia supernova use the same mechanism in a different way.If a binary star system has a white dwarf stealing matter from its companion, and it exceeds Chandrasekhar limit, the white dwarf will collapse and detonate. For this contibuttion he was awarded the 1983 Nobel Prize in Physics
These calculations contributed to the eventual understanding of supernovas, neutron stars, and black holes, and the production of the elements in the periodic table.