The Man who “Dwarfed” the Stars:

    “CHANDRA” (Subrahmanyan                    

                                 Chandrasekhar)

_________________________________________________________________________

 

by

           Dr. Dipanjan MITRA,

                        Astrophysicist,

               National Centre for Radio Astrophysics,

               Tata Institute of Fundamental Research,

 

 

Article published in The Asianists' ASIA Edited by T. Wignesan Centre de Recherches sur les Etudes Asiatiques Paris France http://www.stateless.freehosting.net/menupage.htm

 

 

               Pune University Campus,

               India  

 

 

 

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Acknowledgement: Major parts of this article are compilations made after
reading the two sources of reference given in the notes and bibliography section.

I would like to thank my wife Anindita Mitra for her help in compiling

the bibliography of S. Chandrasekhar, adapted from one of the reference works [2].

{For specialised terminology used in this article, please consult the “glossary” given at the end of this article. The next volume of The Asianists’ Asia  will carry a complete bibliography of Professor S. Chandra’s articles and books by Dr. and Mrs. Dipanjan MITRA, work on which has already begun. Editor.}

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Professor Subrahmanyan Chandrasekhar (more popularly known as Chandra) was undoubtedly one of the greatest scientists of the 20th Century. Already at 18, Chandra stepped into the international scientific scene, and ever since has pursued an impeccably illustrious scientific career until his death at the ripe old age of 85. He was a talented scientist, endowed with outstanding mathematical skills, and imbued with a passion for science and a distinct style of work ethic. His works span a vast range of subjects, and in each of these areas, he displayed total mastery.

 

Chandrasekhar was born into a cultured Brahmin Tamil family.  He graduated at the age of 18 from Presidency College, Madras, and shortly after that, he had the opportunity of spending some time with his uncle, Professor Chandrasekhar V. Raman in Calcutta. Raman had just then discovered the famous Raman Effect. It was an exciting time for science.  New ground-breaking scientific discoveries were being made. At this point Chandra wrote his first scientific paper: "Thermodynamics of Compton Scattering with Reference to the Interior of Stars". His interest in stellar physics was already aroused by reading the classic book: The Internal Constitution of Stars, written by the great astrophysicist Sir Arthur Eddington.

 

Further, Chandra became aware of the newly discovered Fermi Dirac statistics from Professor Arnold Sommerfeld who happened to be visiting Madras at that time. He immediately applied his newly-obtained knowledge and wrote the second paper: “Comptom Scattering and the New Statistics” which he communicated to Professor W.A. Fowler in Cambridge with a plea to have it communicated to an appropriate journal. This paper was published in the Proceedings of the Royal Society of London. These sets of events boosted young Chandra’s morale. Very soon he became aware of Fowler's work on the application of the Fermi Dirac statistics which were essential to explaining the stability of White Dwarfs. He lost no time in understanding the implications of these discoveries, and thus went on to derive his well known mass-radius relation for White Dwarfs.

 

In 1930, he went to Cambridge to work under Fowler’s guidance, a great way to begin his illustrious career in astrophysics, a career which remained at high-pitch till the very last day of his life.

 

Chandra, in keeping with his particular tastes, skills, and temperament, chose a scientific area of research which he pursued to its depths. He liked to be precise in his work. Using his fantastic mathematical gifts and his ability to sustain reflection for long periods at a time, he would carefully build up the subject of his research. He published his works at regular intervals in scientific journals, and after a few years of having felt that he had understood the subject well enough, he would write a book on the subject, and then he would move on to another field of research. Each of his books is a classic today and is used as text books by most professional astrophysicists.  It is however quite impossible to write a short essay covering Chandra's immense body of work and do justice to the genius who authored it. It would require a whole volume. In any case, here we will first try to summarize the various fields of Chandra's research in chronological order, and then discuss in greater detail his work on White Dwarfs which fetched him the Noble Prize, jointly with Professor Fowler, in 1983.

 

Chandrasekhar's scientific career shows a pattern of eight distinct periods. He started his career in 1929 in an effort to understand the physics of stars and continued this phase until 1939. His contribution to stellar physics during this period is monumental. He developed the fundamental basis for relativistic astrophysics which led to the prediction of neutron stars and black holes. Around 1939, he summarized all his results in a book: An Introduction to the Study of Stellar Structure.

 

By this time Chandra had left Cambridge and joined the Yerkes Observatory of the University of Chicago in 1937. After the completion of his work in stellar structure, Chandra concentrated on stellar dynamics. His well-grounded mathematical skills led him to do detailed calculations in order to solve questions related to equilibrium of stellar systems. He is also well known for his work on estimating cluster relaxation and evaporation times. He dedicated 5 years (1939-1943) to these subjects and wrote the Principles of Stellar Dynamics which was published in 1942.

 

One of Chandra’s favourite areas of  research was radiative transfer, and he devoted the period: 1943-1950 to investigating this domain. He used elegant techniques to investigate difficult problems on planetary and stellar atmospheres. These were problems of classical physics posing extremely difficult mathematics, and only someone with Chandra's mathematical gifts could have addressed these problems. During this period, he also contributed to the theory of negative ion of hydrogen. As usual he wrote a book: Radiative Transfer, in 1950.

 

Chandra continued to look at problems which posed exciting challenges in astrophysics.

This led him to tackle the area of magneto hydrodynamics. He worked in the area of turbulence, Galactic magnetic field and its generation, and the theory of collisionless

plasma. His classic monograph, "Hydrodynamic and Hydromagnetic Stability", published

in 1961, is a summary of his monumental contribution to this subject.

 

Next, motivated by the mathematical beauty of the subject, Chandra spent the period from

1961 to 1968 working on virial methods and classical ellipsoids. Here, he played

the role of resurrecting this subject which he pointed out had been largely neglected.

As a responsible scientist he compiled his work in a book, entitled: Ellipsoidal Figures of

Equilibrium, in 1969. Chandra is known to have shown some impatience during this period.

He wanted to go back to the problem of relativistic astrophysics which he left

during the 1930s. This was quite natural as several of his theories which promoted

reflection on neutron stars were being re-discovered. He devoted the next years of his

life to studying another important scientific problem, the stability of black holes. Around 1983, Chandra wrote the classic work: The Mathematical Theory of Black Holes. He was over 70 years at that time, but with unabated enthusiasm, he continued to work on the theory of colliding gravitational waves and non-radial perturbations of relativistic stars during the period 1983-1995.

 

Chandra’s last book was on Newton's Principia. Chandra also finished the book, entitled: Newton's Principia for the Common Reader, which was published only a few weeks before he passed away.

 

Professor Chandrasekhar was an extremely eminent and responsible scientist. He was highly productive throughout his life. From his work a pattern seems to emerge. He started his work

on relativistic stars. He moved on to other areas of research in order to educate himself. His standards were high, and as a result all his books remain as masterpieces with us. He returned to the subject of stellar black holes towards the last stage of his career. By that time, he had perfected and equipped himself with all manner of skills to address seminal problems in black hole physics. His comeback coincided with a time when many more eminent young researchers were working on the black hole problem. Chandra was thrilled to work with this highly gifted group of youngsters.

 

 

 

Professor Chandrasekhar's work on Stellar Physics

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The field of Astrophysics started with the study of stellar objects. Yet for centuries it remained a mystery as to why stars are the way they are. The first important clue towards understanding them came from the observation of the absorption of Fraunhoffer spectral lines from the sun which were identified from the atomic species present in the sun. This fundamental discovery prefaced the unveiling of the physical constituents of a star. The star was understood to be a gaseous ball made up of atoms as well as ionized plasma (electrons and protons) and which was able to produce its own light.  Understanding the physical constituents of stars became an exciting research area in the early part of the 20th  century. The newly discovered science of quantum mechanics therefore found instant application on stars. Here let us digress a bit to actually understand what one was trying to understand about stars.

 

Stars are mostly observed using an optical telescope. They are formed through gravitational collapse of a huge cloud of material and eventually shine as they have the ability to produce their own light. The data obtained from observing stars can be used to finding a few basic parameters for any star, as for instance: the mass, the luminosity (total energy output per second), the radius and the composition of the outer layer. Further stars (like our sun) are like shining globules in the sky emitting constant light. Indirect evidence for this comes from geologists who find fossil algae in the earth more than a billion years old. From this they estimate that the temperature of the earth then should have been very similar to that of what it is today in order for the algae to survive. This indicates that the sun has been shining in a very similar way a billion years ago.  However boring it might be to observe such constant globules of light in the sky, this constancy of stars proved to be exceedingly important towards understanding these objects. Such a stable configuration present in stars demands that the forces that are acting inside a star should be in perfect equilibrium. The question is, What are the various forces (or pressures) that hold a star together?

 

Naively speaking, two contrapuntally acting pressures need to be presumed in stars which tend to balance each other up. Consider a very small volume element at some point in the star. The pressure acting inwardly in this element should be exactly the same as the outward pressure, and if this were not the case, there would be a net unbalanced pressure which would cause this small volume element to deviate from an equilibrium state; this, as we pointed out, cannot occur due to the fantastic equilibrium observed in stars. The inwardly acting pressure is the gravitational pressure which acts radially inward and tries to push the volume element towards the centre of the star.  The outward pressure, which is the characteristic of the material in this volume, and its temperature, act in the opposite direction (radially outward) while exactly cancelling the inward gravitational force.  For the star to remain in equilibrium, this pressure balance usually known as "Hydrostatic equilibrium" needs to hold good at all points in the star. Considering this simple balance in holding good or together, one can readily show that the typical temperature in the stellar interior is of the order of 10 million kelvin.

 

However, the constancy of a star requires that another kind of equilibrium should also

hold together. This is known as thermal equilibrium, which demands that the temperature be constant at every point in the star. This is however not quite possible, as we know that the temperature on the surface layer of a star is a few thousand degrees kelvin while the stellar interior is at 10 million K. Under such conditions there will be a net energy flow

out of the star which we measure as the luminosity from the star. Hence the thermal equilibrium operating in a "constant" star is of the kind where there is a constant supply of energy within the star which replenishes the amount of energy carried away from the star maintaining a constant temperature gradient across the star. It came as one of the greatest revelations that nuclear fusion transmuting hydrogen into helium in stars can sustain a constant star for billions of years. Spectroscopic observations of stars found that stars are indeed rich in hydrogen proving that stars produce their own light by burning hydrogen and thereby producing helium and other heavier elements. (This process is commonly known as nuclear fusion and can be readily found in any high school physics text book.) The net flux which flows outwards causes another force acting outward from the star, and this goes by the name of radiation pressure.

 

To summarize then, for a star to be in constant equilibrium, the net pressure acting outward, i.e., the gas pressure and radiation pressure should balance the inward acting gravitational force in a star.  And to maintain this equilibrium, the star should continue to burn its nuclear fuel.  This remarkable theory of stability of stars was put forward by Sir Arthur Eddington, published in his book: The Internal Constitution of Stars, in 1926.

 

The next important question that arises is what happens to stars after they have exhausted their nuclear fuel?  It means that if the stars cannot produce their own energy, the stars would cool down, and both the gas pressure and radiation pressure would decrease, while the gravitational pressure would take over causing the star to collapse. At that time, this was a puzzling issue, as Sir Arthur Eddington himself commented, "I do not see how a star which has once got in the compressed state is ever going to get out of it...". And to add to the puzzle, the discovery of white dwarfs ( a star in a compressed state with extremely high density of 10^6 gm/cc) appeared to challenge this successful theory.

 

This paradox was resolved by Fowler. The gas pressure in fuel efficient stars is dictated by the classical Boyles law. However, at high densities where matter is extremely compressed, Fowler argued that quantum mechanics is important and the pressure should be calculated according to the Fermi Dirac statistics.  He argued that the material at these densities will develop another outward pressure, known as the degenerate pressure, which will halt the gravitational collapse.  This theory could easily explain the existence of highly dense stars like white dwarfs.

 

Such was the state of stellar theory when young Chandra began his scientific career.  Following this seminal idea put forward by Fowler, Chandra almost immediately theoretically derived the exact mass-radius relation for a completely degenerate white dwarf.  His results showed that the, the radius of the white dwarf is proportional to the cube root of the mass; density is proportional to the square of the mass.  At that time his theory led to the idea that all stars should end their lives as white dwarfs. 

 

After finishing this work in Madras, India, Chandra prepared to go to Cambridge to work with Fowler. During his voyage he realized that his results on a white dwarf were limited to the case where the star's electron gas was moving with non relativistic speed (speed much less than the velocity of light).  But when densities are high the electron gas attains relativistic speeds (speeds close to the velocity of light), and the gas pressure gets modified as predicted by special theory of relativity. Considering the case that a white dwarf is completely degenerate and relativistic, Chandra went on to discover one of the most intriguing results in astrophysics. He concluded that in such a case there exists a limiting mass for the white dwarf which merely depends on the universal constants and the mean molecular weight (mu_e) of the star as:

 

 M_limiting = 5.76 mu_e^(-2) Msun (in units of solar mass).

 

This limiting mass is rightly known as Chandrasekhar limit.

 

For mu_e = 2, fully degenerate helium, M_limiting = 1.4 Msun.

 

It is worth mentioning that simultaneously two other scientists, W. Anderson and E.C. Stoner (1929) had independently investigated this problem, but did not pursue it to get to the conclusion Chandra had reached. 

 

From then on, Chandra was unstoppable. He went on to first establish in intricate detail a complete theory of white dwarfs taking special relativity into account.  By 1936 he was able to answer another puzzling question regarding the mass of stars.  It was curious to find

that thousands of stars found in the sky seemed to have masses which were confined to very narrow mass range, varying at the most about ten times with respect to the mass of our sun. Chandra demonstrated that the maximum mass of a stable star is again a combination of fundamental constants which give a mass in the ballpark limit of 30 Msun, close to what is observed.

 

About the same time around 1932-34 Chandra focussed his attention on the eventuality of massive stars. He first established a very important result: that being the criteria of developing degeneracy in a star. To summarize his findings, a star would develop degeneracy if the radiation pressure be less than 9.2% of the total pressure. Then he found that stars with masses exceeding 6.65 mu_e^-2 Msun, will have radiation pressure greater than 9.2% of the total pressure, and thus the star cannot develop degeneracy and so degenerate pressure cannot be invoked to save the star from collapsing. Being extremely cautious (as that was his style, not to publish anything which did not have any suitable mathematical basis), he posited that a star unable to develop degeneracy will keep collapsing until perhaps when the atomic nuclei of the stellar matter are close enough to change the expression for calculating pressure.

 

It was Baade and Zwicky (1934) who went ahead to declare what Chandra had indicated, that is, when matter is dense the neutron will drip out of their nuclei to form a neutron star which is rich in neutron and is supported against gravitational collapse due to neutron degenerate pressure. Chandra appreciated their conclusions and around 1939 stated that stars more massive than

 

M_limiting but less massive than 6.65 mu_e^-2 Msun

 

would collapse into a neutron star releasing huge amounts of gravitational

energy, perhaps resulting in the supernova phenomenon.

 

By 1940, stellar physics reached an advanced stage. Most of the issues relating to stability of stars and their energy sources were resolved. Chandra proceeded to devote his time now to answering detailed questions relating to end stages of stellar evolution, particularly what happens in the core of stars after nuclear burning is over. Another seminal result evolved in this quest. He concluded (along with other co-workers) that if the mass of a star is less than M_limiting, the star would find peace as a degenerate white dwarf. For mass configuration greater than M_limiting, the star will be in an uneasy state of inequilibrium and has to shed its mass to eventually settle down peacefully in a completely degenerate state. This shedding of mass is commonly known as the Type I supernova.

 

Chandrasekhar’s detailed study and illuminating results on stellar structure created waves in the scientific community. The results relating to the fate of massive stars settling as neutron stars was remarkable. It was Oppenheimer and Snyder (1939) who took these significant results and conjectured upon what could happen to sufficiently massive stars. They said that such a heavy star would collapse into a singularity only around which "..its gravitational field will persist..". This is known as the black hole.

 

Today precise measurements of neutron star masses are almost equal to 1.4 Msun. A neutron star has been found approximately 30 years of its prediction inside many supernova remnants, the most prominent being the crab nebula. Indirect evidence has shown the existence of black holes. These are remarkable confirmations of Chandra’s theory. He came at a time when classical theory of stars failed to explain observations of highly dense stars. Chandra played a significant role in erecting the theory of relativistic astrophysics which continues to be a major area of research in astrophysics today.

 

 

Personal Profile

 

Chandra was born in Lahore (capital of Punjab province in British India) on 19 October 1910.

Chandra was the first son of C. S. Ayyar and Sitalakshmi. He had two older sisters, four younger sisters and three younger brothers. His father worked in the railways as an assistant auditor-general and his assignments often required a change of work place. At the age of six, Chandra's family moved from Lahore to Lucknow, Uttar Pradesh (a province in Northern India). Two years later C. S. Ayyar became the deputy accountant-general in Madras (Chennai today). In Madras, he established a home where the family stayed while he travelled.

 

Chandra was a healthy and charming child and sometimes "unbearably mischievous", according to Chandra's mother Sitalakhsmi.

 

             “As a child,” his sister Bala recalls, "he used to take the

             lion's share of everything. He would break his things

             first and take my elder sister's. He would keep them for himself,

             because he would claim they were his. They were then given to him".

 

                                                                                                                                                                                                                                                                                                                                                              Chandra's parents began all their children’s education at home. This was a common practice among middle-class families during that time due to poor educational facilities available in public or municipal schools. Amongst the English-speaking educated parents of that time significant attention was given to educating children in English as that was a prerequisite to getting a high profile job in British India.

 

Efforts were also made to learn the mother tongue which was Tamil in Chandra's family.

Chandra learned Tamil from his mother and English and arithmetic from his father.

In the early years Chandra recalls, "My father used to teach me in the mornings before

he went to office, and then after he went to office, my mother would teach me Tamil. In

the afternoon she would supervise both the English lessons and the Tamil lessons we had

to do." Chandra thoroughly enjoyed learning English and arithmetic. His father used

to give him assignments and Chandra would finish them including one or two more chapters

ahead of what he was taught. His father was amazed by this, but soon realized that

they had an exceptionally bright child in their midst.

 

Chandra went to a regular school in Madras in 1921 when he was 11 years old. He found

his initial days in school very disappointing as he did not find the conventional formal

education to be easy nor pleasant. Only when he discovered that the curriculum included geometry and algebra that Chandra got excited. He started to learn maths well ahead of the rest of the classes. He was particularly engrossed in learning maths and finished all the

courses in the shortest possible time. He became a freshman in Presidency College, Madras, when he was only fifteen years old. Undoubtedly in school Chandra was the "best" pupil and was even regarded as a prodigy.

 

Chandra was a very sensitive and warm hearted person. As he grew older he noticed that

his sisters experienced a certain kind of discrimination at home. They were not given

the facilities that the boys enjoyed in the family. His sisters had to marry at an

early age, thus putting an end to their formal education. They were unhappy about the restrictions imposed on them. Disillusioned by such social practices, Chandra decided to divert all his energies to studying mathematics. He found ways to mentally withdraw himself from the immediate family and concentrate on his studies.

 

At college, Chandra studied mathematics, physics, chemistry, English and Sanskrit. He was fascinated by English and read many classics diligently. In two years he finished his intermediate at the Presidency College with distinctions in physics, chemistry and mathematics. He was then all set to start his B.A. honours degree.

 

Chandra wanted to take mathematics for his honours. On the other hand, Chandra's father wanted him to study physics. Following the trends of the moment, he wanted his son to go to England to pass the Indian Civil Service examination and become a noted ICS officer. That, according to him, was the most elegant career for a brilliant young man like Chandra. C. S. Ayyar was an authoritarian head of the family with traditional views. But Chandra was determined to do science and basic research.

 

He was happy to be doing physics honours. He already knew about two great scientists in the Indian scene, the great physicist C. V. Raman, his uncle, and the illustrious autodidact mathematician Srinivasa Ramanujan.

 

He had however to struggle with his father’s dictates. Mr. Ayyar insisted on his son becoming

an ICS officer. Fortunately for Chandra, his mother gave him the required moral support.

    

          "You should do what you like. Don’t listen to him; don’t be intimidated,"

          she told her son.           .

 

Chandra was lucky to have such a strong-willed and devoted mother who, against all odds, stood  by Chandra till the very last day of her life.

 

With moral support and blessings from his mother, Chandra was encouraged. He took up

physics honours, and he devoted much time to studying physics and maths. Special

privileges were allowed him in college: despite his being a physics student, he was allowed to attend all the mathematics courses. Everyone knew that Chandra was specially gifted, and favours were bestowed on him without any apprehension.

 

The year 1928 became an extraordinary time for Chandra. He was then able to visit Raman

in Calcutta (Kolkata) where he also met several other distinguished scientists like Saha and Bose. Exciting new scientific discoveries were being made then. Chandra's brilliance was recognized by the great men he met, and from them Chandra got the required confidence to pursue research. It was around that time too when Sommerfield visited Madras to give a lecture. Chandra was given the task of taking Sommerfeld around to visit several places in Madras. During the tour, young Chandra spent a great deal of time talking science with the great scientist. In this way, he became aware of the advances being made in science. This encounter particularly marked the early stages in the development of the great scientist that Chandra was to become.

 

        As Chandra said, " From a purely scientific point of view, the most crucial

        incident was my meeting with Sommerfeld when he visited Madras in 1928".

 

 By 1930, Chandra had published several scientific papers. He sent one of his papers to Professor Fowler in Cambridge. The famous scientist was thoroughly impressed by Chandra's work and communicated the paper to the Proceedings of the Royal Society. Chandra wanted to do his Ph.D. under the supervision of Prof. Fowler at Trinity College, Cambridge, England. His desire to go to England to do a Ph.D. created a certain amount of unrest in the family; besides, he also had some trouble getting proper admission to Trinity College. Despite all the difficulties, Chandra managed to go to England in July 1930.

 

He was young and had to travel all alone several thousand miles away from home, and once there put up with a new place, new culture, and new society. Chandra was probably a bit scared and confused, but his insatiable urge to undertake scientific research, goaded him along.

.

 

Cambridge at that time was a “dreamland” for a young scientist like Chandra. Suddenly he

found himself amongst a galaxy of scientists like Sir Arthur Eddington, Dirac, Milne, and so forth. Excited as he was, he nevertheless remained in full control of himself. He wrote to his father

       

        "..I have to realize more fully that I have come down 6000 miles,

          not to fill away my time, but by utilizing opportunities in the proper

          way, to at least compensate for the anxiety which my coming is bound

          to cause in others".

 

Of course Chandra did more than just compensate. He quickly immersed himself in very vital problems in astrophysics and made fundamental contributions to them. Soon after his Ph.D. degree which he obtained in 1933, he wanted to continue staying in Europe in order to be able to work in his field of research. He applied for the highly prestigious Trinity Fellowship. The only other Indian who had been elected to the Trinity Fellowship was Srinivasa Ramanujan. Chandra got the fellowship, and this ensured his residence in England for a few more years.

 

While he made great strides in his scientific career, he was however constantly unhappy and lonely. This was especially so because he felt his work was not being appreciated by some of his distinguished colleagues. In particular, Sir Arthur Eddington was unhappy about Chandra's work. Eddington was considered to be a "king" when it came to understanding stars as he had laid the foundation for the classical theory of stars. He eventually concluded that every star, no matter what its mass, could reach an equilibrium state and become a white dwarf.

 

But Chandra's conclusion that massive stars cannot reach such an equilibrium state

distressed Eddington. The controversy between Eddington and young Chandra became serious.

 

Eddington tried to dismiss Chandra's findings on almost every occasion he got. Even

other scientists who otherwise agreed with Chandra, did not criticize Eddington in public.

Chandra was shocked and puzzled. Chandra felt that the differences were not based

on honest scientific arguments. Chandra hence decided to finally change his area of research.

 

He was convinced that his work was correct and did not want to waste energy in trying

to prove it by fighting the “greatest scientist” in the world. While much can be said about

the controversy, what Chandra said was

    

          "I do not think Eddington's tirade against me was derived from any personal

           motives. You may attribute it to an elitist, aristocratic view of science and

           the whole world. Eddington was so confident of his views that as far as

           he was concerned he was a Gulliver in a land of Lilliput. He was not affected

           in the least by what other people said or did not say."

 

Chandra - even against all that was being done to him -  deeply respected the great scientist that Eddington was. That was typical of Chandra.

 

Chandra spent a few years in Cambridge. But he needed a change. His father was hoping

that Chandra would return home, but Chandra did not want to go home. India certainly

was not the place where he could do research, and, in England, it was difficult for Indians to

get a permanent position. It was then that he was offered a position in the USA at the Yerkes Observatory, as a research associate by Prof. Otto Struve. He decided to take  that offer up in January 1937. Before that however he considered a short visit to India. He was homesick, and it was also time that he began to worry about finding his soul-mate.

 

Chandra got married to D. L. Lalitha on 11 September 1936. Lalitha and Chandra met when they were students in the physics honours course in Madras. She had an instant liking for the handsome and sparkling Chandra. After Chandra went to England, for six years they exchanged letters. Lalitha was also interested in continuing her research in physics. When Chandra was away Lalitha did struggle somewhat to get her career going. But she spared Chandra her frustrations and waited patiently for him to decide on his/their future. Finally, they were united; the couple then set out to lead their new life together in America (via England). Lalitha was a perfect partner for Chandra, even if the couple remained childless through nearly a half a century of being together. Even in a distant land she knew what her role was.

 

She said "...the main thing for Chandra and me was to understand each other. The first

priority for him was his science. There was not much time for other things, which I

well understood and appreciated. She willingly gave up the idea of continuing a serious

scientific career of her own. Around this time Chandra also got an offer to return to India

and work there. But Chandra and Lalitha were determined to stay in America, in Williams Bay, Wisconsin, which became their home. Chandra launched a new career from the Yerkes Observatory of the University of Chicago.

 

And what an illustrious career it was! His prolific contributions to widely diverse

areas in astrophysics have made him a living legend in scientific circles. He had

authored a dozen books and bagged several awards and prizes. He was given the

Bruce Medal (Astronomical Society of the Pacific) Gold Medal of the Royal Astronomical Society, the Royal Medal of the Royal Society (on the formal approval of Queen Elizabeth), the National Medal of Science (awarded by President Johnson), Padma Vibhusana (awarded by President of India), Srinivasa Ramanujan Medal (Indian Academy of sciences), the Noble Prize in Physics and the Copley Medal of the Royal Society. He was an excellent teacher and had more than fifty Ph.D. students under his guidance. He was the sole editor of the Astrophysical Journal for almost twenty years and was chiefly responsible for making it the foremost journal, in its specialty, in the world. Chandra however was quite modest about assessing his contributions. In a lecture delivered by him at the Indian Academy of Sciences, he said:

       

           "The pursuit of science has often been compared to the scaling of mountains,

           high and not so high. But who amongst us can hope, even in imagination,

           to scale the Everest and reach its summit when the sky is blue and the air is still,

           and [in] the stillness of the air survey the entire Himalayan range in the dazzling  

           white of the snow stretching to infinity? None of us can hope for a comparable

           vision of nature and the universe around us. But there is nothing mean or lowly in

           standing in the valley below and awaiting the sun to rise over Kinchinjunga.[sic]"

 

Chandra's pursuit of science was solely in the spirit of experiencing the beauty of it, and he believed that it was not restricted only to great minds. So, he said:

    

       " This is no more than the joys of creativity are [being] restricted

       to a fortunate few. They are, indeed, accessible to each one of us provided we are attuned

       to the perspective of strangeness in the proportion and conformity of the parts of

       one another and to the whole. And there is satisfaction also to be gained from     

       harmoniously organizing the domain of science with order, pattern and coherence.."

 

 

 

Bibliography: BOOKS by Chandrasekhar Subrahmanyan

Compiled by
Anindita Mitra

1. An Introduction to the Study of Stellar Structure
. Chicago: University of Chicago Press, 1939. Repr. New York: Dover, 1958, 1967. {Translation in Japanese (Tokyo: Kodansha Press, Ltd., 1972) and Russian have appeared.]

2. Principles of Stellar Dynamics.
Chicago: University of Chicago Press, 1942. Repr. New York: Dover, 1960.

3. Radiative Transfer.
Oxford: Clarendon Press, 1950. Repr. New York: Dover, 1960.A Russian Translation exists.

4. Plasma Physics: Notes Compiled by S.K.Trehan From a Course given by S. Chandrasekhar at the
University of Chicago. Chicago: University of Chicago Press, 1960. Repr. 1962, 1975.

5. Hydrodynamics and Hydromagnetics Stability.
Oxford: Clarendon Press, 1961. Repr. New York: Dover, 1970, 1981. A Russian Translation exists.

6. Ellipsoidal Figures of Equilibrium.
New Haven: Yale University Press, 1969. Repr. New York: Dover, 1987. A Russian Translation exists.

7. The Mathematical Theory of Black Holes.
Oxford: Clarendon Press, 1983. Repr. in Russian (Moscow: Mer Press), 1986.

8. Eddington: The Most Distinguished Astrophysicist of His Time.
Cambridge: Cambridge University Press, 1983.

9. Truth and Beauty: Aesthetics and Motivations in Science.
Chicago: University of Chicago Press, 1987.

10. Selected Papers ( seven volumes).
Chicago: University of Chicago Press, 1989-91.

11.
Newton's Principia for the Common Reader. Clarendon Press, 1995.



--------------------
REFERENCES
--------------------

[1] Wali, Kameshwar C. Chandra. A Biography of S. Chandrasekhar.  33
halftones. 6 x 9 1990 Series: (CEP) Centennial Publications of The
University
of
Chicago
Press, 352 p.

[2] "A tribute to Subhramanyum Chandrashekhar", Journal of Astronomy and Astrophysics,
1996, Volume 17 (Numbers 3 & 4), Published by the
Indian Academy of Sciences.

-----------------------
Glossary
-----------------------

"radiative transfer"
Study of the physical process by which radiation travels
through a medium.

"Fermi Dirac statistics"
http://en.wikipedia.org/wiki/Fermi_statistics

In statistical mechanics, Fermi-Dirac statistics determines the
statistical distribution of fermions over the energy states for a
system in thermal equilibrium. Fermions are particles which are
indistinguishable and obey the Pauli exclusion principle, i.e., that
no two particles may occupy the same state at the same
time.
Statistical thermodynamics is used to describe the behaviour of
large numbers of particles. A collection of non-interacting fermions
is called a Fermi gas.

"cluster relaxation time"

The relaxation time is the typical time for gravitational interactions
with other stars in the cluster to remove the history of a star’s
original velocity.

"Evaporation time"
  The evaporation time for a cluster is the time required for the
cluster to dissolve through the gradual loss of stars that gain
sufficient velocity through encounters to escape its gravitational
potential.

"quantum mechanics":
http://hepwww.rl.ac.uk/WIRED/native-1.1/noframes/glossary.html

The laws of physics that apply on very small scales. The essential
feature is that energy, momentum, and angular momentum as well as
charges come in discrete amounts called quanta.


"virial methods"
  A special form of the virial theorem states that, for a stable,
self-gravitating, spherical distribution of equal mass objects (stars,
galaxies, etc), the total kinetic energy of the objects is equal to
minus 1/2 times the total gravitational potential energy.  In other
words, the potential energy must equal the kinetic energy, within a
factor of two.  Virial methods are application of the generalized form
of this theorem to several physical systems.

"Classical Ellipsoids"
Classical Ellipsoids are geometric surfaces whose plane sections are all ellipse
or a circle.

"Black Holes"
http://www.eclipse.net/~cmmiller/BH/blkbh.html

Once a giant star dies and a black hole has formed, all its mass is
squeezed into a single point. At this point, both space and time
stop. It's very hard for us to imagine a place where mass has no
volume and time does not pass, but that's what it is like at the
centre of a black hole.

The point at the centre of a black hole is called a
singularity. Within a certain distance of the singularity, the
gravitational pull is so strong that nothing--not even light--can
escape. That distance is called the event horizon. The event horizon
is not a physical boundary but the point-of-no-return for anything
that crosses it. When people talk about the size of a black hole, they
are referring to the size of the event horizon. The more mass the
singularity has, the larger the event horizon. The structure of a
black hole is something like this:

Many people think that nothing can escape the intense gravity of black
holes. If that were true, the whole Universe would get sucked up. Only
when something (including light) gets within a certain distance from
the black hole, will it not be able to escape. But farther away,
things do not get sucked in. Stars and planets at a safe distance will
circle around the black hole, much like the motion of the planets
around the Sun. The gravitational force on stars and planets orbiting
a black hole is the same as when the black hole was a star because
gravity depends on how much mass there is--the black hole has the same
mass as the star, it's just compressed.

Black holes are truly black. Light rays that get too close bend into,
and are trapped by the intense gravity of the black hole. Trapped
light rays will never escape. Since black holes do not shine, they are
difficult to detect.


"Supernova"

http://www.galex.caltech.edu/glossary.html

  the death explosion of a massive star, resulting in a sharp increase
in brightness followed by a gradual fading. At peak light output,
supernova explosions can outshine a galaxy containing a billion
stars. The outer layers of the exploding star are blasted out in a
radioactive cloud. This expanding cloud, visible long after the
initial explosion fades from view, forms a supernova remnant.


"Magnetohydrodynamics"
http://www.spacescience.org/ExploringSpace/Glossary/1.html

  Just as HydroDynamics is the study of the motion and dynamics of
fluids such as water, MHD is the study of plasma motion and dynamics
in the presence of a magnetic field.


"Galactic magnetic field"

http://www.daviddarling.info/encyclopedia/G/galactic_magnetic_field.html

A weak and largely disordered magnetic field, with a strength of about
5 × 10-10 tesla, that pervades the disk of the Milky Way Galaxy and
controls the alignment of interstellar dust particles. Similar fields
exist in other disk galaxies; those of elliptical galaxies are more
difficult to estimate because of the lack of interstellar matter.

"collisionless plasma"
 

A low-density gas in which the individual atoms are charged, even
though the total number of positive and negative charges is equal, maintaining
an overall electrical neutrality. For a collisionless plasma the charged particles
can move around freely without being under the influence of any other force due
to the other particles in the plasma.

 

© Dipanjan MITRA, India-2004

 

Text Box: The Asianists’ Asia, Vol. III (August-December 2004) Paris, France: ISSN 1298-0358 (Assn. n° 0941011951)
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