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Chandrasekhar S.

posted Dec 30, 2014, 6:06 AM by   [ updated Jun 27, 2022, 9:14 PM by Upali Salpadoru ]
Chandrasekhar Subramanyan. 1910 – 1995

 NASA sent an X’ ray Laboratory into space, on 23rd July 1999.  It was named ‘Chandra’ in honour of   Chandrasekhar Subramanyan.

Fig.1 Chandrasekhar Subramanyan      

Date of Birth: 19th October.   Place of Birth: Lahore. India.

     Sithalakshmi Balakrishnan was overjoyed to get a son, after two daughters. As if they had foreseen his destiny they named him ‘Chandra’ (moon). Finally he became a glittering star in the sky of Astronomy.

Fig.2 Lalitha  Chandrasekhar near  the model of X-Ray Observatory.

   Sithalakshmi was an unusual Brahmin lady, belonging to a free thinking family, who lived in Lahore, in Pakistan. Her husband was Subrahmanyan Ayyar who was an accountant at the top of the Indian Civil service. While being a good husband to a very demanding man and  bringing up 10 kids, Sitha had the time to produce Tamil translations of Henrik Ibsen and Tolstoy.

  It may be amazing to hear now, that the Subrahmanyan children did not attend school when young. Their mother taught them Tamil and English while the father devoted his entire free time coaching them up in other disciplines. 


When Chandra was six years, the family moved to Madras and his father became the Deputy Accountant General. He had to employ private tutors for the children.


Chandra was sent to Hindu High School in Madras at the age of 12.  He was there for three years. At the start of the second academic year, there was hardly anything that the teachers could teach. During the holidays he had mastered, all by himself, more than half of the mathematics and science text books. He excelled in all academic disciplines; devoured books at an amazing rate of 100 pages an hour. Not sparing fact and fiction, he consumed the literary classics ranging from William Shakespeare to Thomas Hardy. He also developed an interest in classical music. 

Father had a dream; to get his gifted son to follow his footsteps and enter the Indian Civil Service.


At the age of 15 Chandra entered Presidency College in Madras, where his uncle got a gold medal in 1904. Although Chandra studied many subjects including Sanskrit and English, his favourites were mathematics and physics.  Inspired by his countryman S. Ramanujan, who excelled in mathematics at Cambridge, he was inclined to pursue him.  His father pointed out that would not pave the way to Indian Civil Service. His mother taking a more democratic attitude allowed her son to have the final say. Ultimately he compromised with physics honours, for which his father agreed, as it was the field of his Nobel Laureate brother Sir C. Venkata Raman.


  His father’s brother, paternal uncle, discovered the Raman scattering and the Raman effect. The nephew too had two major achievements.

  • Winning the heart of his junior, Lalitha Doraisamy who hailed from a well to do family that   lived close to his house
  • Publishing of a research paper titled, “Compton Scattering and the New Statistics” in the prestigious journal, ‘Proceedings of the Royal Society’ .


His uncle, Sir C. Venkata Raman received the Nobel prize for Physics.

Chandra obtained the BSc (Hon) degree in physics at the top of his class along with an Indian government scholarship to Cambridge for postgraduate studies. He was reluctant to leave India, mainly as his mother was not in good health but his Mother insisted that he should go. She wanted her son to emulate his uncle.

Chandra and Lalitha got engaged with the blessings of their parents prior to his visit.

On his voyage to England he became severely sea sick. After recovery, gazing at the deep blue and the sky, his thoughts ascended far beyond the solar system. He combined R H Fowlers views on white dwarfs with his knowledge of ‘special relativity theory’. His calculations showed that a ‘white dwarf star’ could never be more massive than one and a half times the mass of our sun. If it is more massive it will continue to collapse and explode to become a neutron star. More massive stars become black holes. This figure, 1.45 came to be known as the ‘Chandra limit’.

What is a ‘White dwarf’?

The size of a star is maintained by two main forces; the gravitational attraction towards the centre and the pushing out pressure build up due to the nuclear reaction; Hydrogen changing to Helium. When the fuel runs short, a star tends to collapse due to gravity. This increases the density but the cooling is somewhat compensated by the increase of the reaction. Such a star of low magnitude, devoid of the gaseous envelop, but consisting only of the ultra-hot core is termed a ‘white dwarf’.

Two leading astro-physicists in England at the time Sir Arthur Eddington and Prof.E.A. Milne, refused to publish it in the Royal Society Journal.


Chandra sent his paper  to the Astrophysical Journal in America, which published it in March.

At Cambridge he came under the wing of Prof. R.H.Fowler. At the request of Prof. P.A.M. Dirac, he spent his third year conducting research in Copenhagen. On getting his doctorate he was elected a fellow of The Trinity College. Now feeling more secure, he returned to the study of white dwarfs. After using a series of more precise calculations he came to the conclusion that there is definitely an upper limit to the mass of such a star.


He gave a lecture on this subject at the Royal Astronomical Society.  Sir Eddington again not only rejected, but ridiculed him for the theory.  Eddington believed that a white dwarf was the last stage of a star's life. “Why should there be a limit to the mass of a star in its old age?” he asked. Even the most reputed scientists of the day were prepared to believe Eddington rather than an unknown guy from backward India. Chandra was shocked and frustrated. Chandra sought the help of many specialists to check his calculations. No one could detect any error in his work. At the end all astronomers started to use this theory in the study of black holes.

He believed that his critics were mostly acting on racial hatred. Perhaps it must have been the reason for him to leave Cambridge and accept a post among the US academics.


 Although he was deeply in love with the dying flames of the white dwarfs in the far away galaxies, he could not forget his old flame in India.  Bearing the blunt of the charges of the English elite, he came back to India in seeking solace from Lalitha, She had had a long and a patient wait, working as a head mistress, and later at his Uncle’s Raman Institute. Their friends thought Lalitha's broad interests and good judgment balanced Chandra's more serious outlook. “We were married (in India) in September. Lalitha's understanding, support, and encouragement have been the central facts of my life.” he wrote in later life.

While being touring Harvard University,in US, at the invitation of the then Director, Dr. Otto Struve and President Robert Maynard Hutchins of the University of Chicago offered him a position as a Research Associate at the University of Chicago.


Chandra accepted the Chicago offer and migrated to the United States, with his newly married wife.  He joined the faculty of the University of Chicago, where he remained until his death.


He persuaded American Astronomical Society and his University to jointly publish the Astrophysical Journal.  He edited this journal for 19 years and managed to make it the authority in the subject.  The wide popularity of his writings and speeches were also due to the fact that he used perfect grammar, classical style of presentation and perfect pronunciation.


Despite many humiliations, he and Lalitha suffered as non-whites, they became American citizens . Chandra’s father who had tried his utmost to find a suitable position for his son in India was thoroughly disappointed.


Sir Chandrasekar was awarded the Nobel prize,  "for his theoretical studies of the physical processes of importance to the structure and evolution of the stars”.

All along his luminous career he devoted his extraordinary mathematical ability and analytical skills to understand and interpret the aggregation and disintegration of matter in the universe. At his Nobel lecture, he said that he had seven periods.

They were as follows :-

1. Stellar structure, including the theory of white dwarfs (1929-1939);

2. Stellar dynamics, including the theory of Brownian motion (1938-1943);

3. The theory of radiative transfer, including the theory of stellar atmospheres and the quantum theory of the negative ion of hydrogen and the theory of planetary atmospheres, including the theory of the illumination and the polarization of the sunlit sky (1943-1950);

4. Hydrodynamic and hydromagnetic stability, (1952-1961);

5. The equilibrium and the stability of ellipsoidal figures of equilibrium, (1961-1968);

6. The general theory of relativity and relativistic astrophysics (1962-1971);

7. The mathematical theory of black holes (1974- 1983).

   At the end of each period he published a monograph the collection of which had become the ‘vedic scriptures’ in astrophysics..

    Sir Arthur Eddington finally accepted the ‘Chandra Limit’ theory, and made peace. Chandra accepting the Nobel award stated  “During my Fellowship years at Trinity, I formed lasting friendships with several, including Sir Arthur Eddington and Professor E.A. Milne…. Sir Arthur was the best Astrophysicist at the time”.

    Chandra was an enthusiastic teacher who attracted students from all over the world. He was a perfect role model for them. By the time of his retirement, he had guided over 50 students to their Ph.D.s.

     Professor Hans Bethe , a Nobel laureate from Cornell University says, “I was always impressed by the depth and sophistication of Chandra's mind, and its capacity for retention which showed in his writings and speeches on any topic. It was a pleasure to listen to one of his talks. In addition to style, he had the perfect upper-class English accent I have ever heard. Chandra was a first-rate astrophysicist and a beautiful and warm human being. I am happy to have known him”. The present Astronomer Royal, Martin Rees has this to say, "Chandra probably thought longer and deeper about our universe than anyone, since Einstein,"

    Chandra’s saying, “God is the man’s biggest creationshows his religious views.

    Although Chandra was a great admirer of Mahathma Gandhi, during the second world war he supported the allied troops.  He helped the army by conducting research on shock waves and was invited to join the Los Alamos Project too.


    Even after retirement, he continued to live in Chicago where he was made professor emeritus. He continued to give thought-provoking lectures such as Newton and Michelangelo which he delivered at the Meeting of Nobel Laureates held in Lindau. He compared Michelangelo's frescoes in the Sistine Chapel and Newton’s Principia.


     Chandra died at the age of 84 without leaving a successor;.


    His name has become immortal as NASA,  continues to study white dwarfs  and  black-holes through the ‘Chandra X’ray Observatory” launched on 23rd July.