Subrahmanyam Chandrasekhar the Indian astrophysicist


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Subrahmanyan Chandrasekhar was born on 19 October 1910. Today is his 111th birth anniversary. He was an Indian-American astrophysicist who spent his professional life in the United States. He received the Noble Prize for Physics in 1983 along with William A. Fowler for “theoretical studies of the physical processes of importance to the structure and evolution of the stars“. His mathematical treatment of stellar evolution resulted in many of the current theoretical models of the later evolutionary stages of massive stars and black holes. The Chandrasekhar limit is named after him.

Chandrasekhar was born on 19 October 1910 in Lahore, Punjab in British India. This area is now present in Pakistan. He was born in a Tamil Brahmin family. The name of his mother was Sita Balakrishnan (1891–1931). His father was Chandrasekhara Subrahmanya Ayyar (1885–1960) who was a Deputy Auditor General of the Northwestern Railways in Lahore when Chandrasekhar was born. He had two elder sisters, Rajalakshmi and Balaparvathi, three younger brothers, Vishwanathan, Balakrishnan, and Ramanathan. Along with them, he had four younger sisters, Sarada, Vidya, Savitri, and Sundari. His paternal uncle was the Indian physicist and Nobel laureate Chandrasekhara Venkata Raman. His mother was a staunch devotee of intellectual pursuits. She had translated Henrik Ibsen’s “A Doll House”. Credit goes to her for arousing Chandra’s intellectual curiosity at an early age. The family moved from Lahore to Allahabad in 1916. They finally settled down in Madras in 1918.

Subrahmanyan Chandrasekhar was one of the giants of modern astronomy and astrophysics in the 20th Century. Chandra proved that there was an upper limit to the mass of a white dwarf. People know this limit as the Chandra limit. It showed that stars more massive than the Sun would explode or form black holes as they died. Chandra also developed theories on star atmospheres, black holes, and the illumination of the sunlit sky, star mass, and star structures. Chandrasekhar marked the destiny of stars. In 1930, other than him, all the scientists believed that every star would eventually burn out to become a white dwarf. But Chandrasekhar was adamant and not ready to accept it. He went ahead and predicted a number, precisely 1.4, and said that white dwarfs were only formed when stars have a mass less than or equal to 1.4 times the mass of our sun.

Chandrasekhar discovered this on his sail to the UK. One would think that the scientists immediately praised him for this and accepted him among them. But nothing as such happened. Famous physicists including Arthur Eddington criticized his ideas. There was another problem. Even the scientists who regarded his findings did not admit it publicly. However, computer simulations and technological advancements later proved this theory right. After that he was honored by naming the number after him, that is, the Chandrasekhar limit. This limit was later on used to gather more information on supernovas, black holes, and neutron stars and still serve as a building stone in the field.

But as seen later, the contributions of Subrahmanyan Chandrasekhar do not end here. He worked in many different fields of physics which ranged from evolutionary stages of massive black holes to hydrodynamics. He also published ten books on different topics in Astrophysics and worked as the editor of The Astrophysical Journal for almost two decades. His magical hands had touched a good number of topics so that Nasa’s x-ray observatory is named Chandra X-ray observatory after him. Chandrasekhar was not only a good astrophysicist but also an elite and humble teacher. As a teacher, he guided about fifty Ph.D. students. On his birthday, it is likely that we remember this Indian American Astrophysicist who crossed the seas only to bring India a Nobel prize.

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