Science history: The astrophysicist who defined how stars behave
Subrahmanyan Chandrasekhar was so influential, NASA honoured him by naming an orbiting observatory after him. Jeff Glorfeld reports.
The NASA webpage devoted to astrophysicist Subrahmanyan Chandrasekhar says he “was known to the world as Chandra. The word chandra means ‘moon’ or ‘luminous’ in Sanskrit.”
Subrahmanyan Chandrasekhar was born on October 19, 1910, in Lahore, Pakistan, which at the time was part of British India. NASA says that he was “one of the foremost astrophysicists of the 20th century. He was one of the first scientists to couple the study of physics with the study of astronomy.”
The Encyclopaedia Britannica adds that, with William A. Fowler, he won the 1983 Nobel Prize for physics, “for key discoveries that led to the currently accepted theory on the later evolutionary stages of massive stars”.
According to an entry on the website of the Harvard-Smithsonian Centre for Astrophysics, early in his career, between 1931 and 1935, he demonstrated that there is an upper limit – now called the Chandrasekhar limit – to the mass of a white dwarf star.
“This discovery is basic to much of modern astrophysics, since it shows that stars much more massive than the Sun must either explode or form black holes,” the article explains.
When he first proposed his theory, however, it was opposed by many, including Albert Einstein, “who refused to believe that Chandrasekhar’s findings could result in a star collapsing down to a point”.
Writing for the Nobel Prize committee, Chandra described how he approached a project.
“My scientific work has followed a certain pattern, motivated, principally, by a quest after perspectives,” he wrote.
“In practice, this quest has consisted in my choosing (after some trials and tribulations) a certain area which appears amenable to cultivation and compatible with my taste, abilities, and temperament. And when, after some years of study, I feel that I have accumulated a sufficient body of knowledge and achieved a view of my own, I have the urge to present my point of view, ab initio, in a coherent account with order, form, and structure.
“There have been seven such periods in my life: stellar structure, including the theory of white dwarfs (1929-1939); stellar dynamics, including the theory of Brownian motion (1938-1943); 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 polarisation of the sunlit sky (1943-1950); hydrodynamic and hydromagnetic stability, including the theory of the Rayleigh-Benard convection (1952-1961); the equilibrium and the stability of ellipsoidal figures of equilibrium, partly in collaboration with Norman R. Lebovitz (1961-1968); the general theory of relativity and relativistic astrophysics (1962-1971); and the mathematical theory of black holes (1974- 1983).”
In 1999, four years after his death on August 21, 1995, NASA launched an x-ray observatory named Chandra, in his honour. The observatory studies the universe in the x-ray portion of the electromagnetic spectrum.