Chandrashekhar Limit: When does a white dwarf star collapse?

The Chandrasekhar Limit can be expressed as the maximum nonrotating mass which can be supported against gravitational collapse by electron degeneracy pressure. This is commonly understood to be about 1.4 solar masses (i.e. 1.4 times the mass of the sun or about 333,000 times greater than the mass of the earth).

The Chandrashekhar Limit is an upper limit for the mass of a white dwarf. It has been observed that so-called main-sequence stars with a mass greater than about 8 solar masses are unable to lose enough mass to form a stable white dwarf at the end of their lives, and so they form either a neutron star or a black hole.

A brilliant and gifted physicist, Subrahmanyan Chandrasekhar (Nobel, Physics, 1983) had a very public disagreement about what became known as the Chandrashekhar Limit with Arthur Stanley Eddington (while Chandrashekhar was a junior scientist at Cambridge). Eddington ridiculed Chandrashekhar by terming his work "stellar buffoonery". Chandrashekhar had the last laugh, and a Nobel, in 1983. The bitterness surrounding this event contributed to Chandrashekhar moving to the University of Chicago. He returned to this important work only after about three decades.

NASA has honoured him by naming 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.

One episode of the BBC Radio 4 series "Test tubes and tantrums" considers this controversy (Chandrashekhar vs Eddington) - podcast available at: http://www.bbc.co.uk/radio4/science/testtubesandtantrums.shtml