Johnson Cherian.
Google Doodle on Thursday celebrated the 107th birthday of Subrahmanyan Chandrasekhar, the first astrophysicist to have won a Nobel Prize for his theory on the evolution of stars.
The India-born U.S. astrophysicist, who is known for his theory of white dwarfs, studied in Presidency College, Madras and, later, in Cambridge before moving to the U.S. in 1936.
He was barely out of his teens when he wrote his first scientific paper titled “Thermodynamics of Compton Scattering with reference to the Interior of Stars.” Inspired by Fowler’s work based on Fermi-Dirac statistics on the stability of white dwarfs, Chandra, as he was popularly known, turned his attention to investigate the final stages of stellar evolution.
What happens to a star when its nuclear fuel is depleted? Chandrasekhar showed that when this happens, the star undergoes an inward collapse under its own gravity. As the density and pressure increases due to this compression, there are two things – one is the build up of pressure which gives an outward force and the other is the attraction due to gravity which causes the inward collapse.
The play off between these two may cause a supernova explosion, in which the star sends off to space much of its mass. After this explosion, again, there are two possibilities – if the mass of the star were comparable to that of our sun, it would collapse to become a white dwarf.
If on the other hand, initially its mass had been greater than approximately twice our sun’s mass, it will collapse to form a black hole. This mass limit beyond which a star would become a black hole came to be known as the Chandrasekhar mass limit. It is approximately 1.4 solar masses.
All known white dwarfs in the universe have been found to conform to this limit. Like his illustrious uncle, C. V. Raman, Chandrasekhar also won a Nobel Prize, in the year 1983.
