Subrahmanyan Chandrasekhar

Subrahmanyan Chandrasekhar (1910–1995) was an Indian-American astrophysicist renowned for his pioneering work on stellar structure, stellar evolution, and the physics of compact objects. He is best known for the Chandrasekhar limit, which describes the maximum mass of a stable white dwarf star. His contributions fundamentally shaped modern astrophysics and earned him the 1983 Nobel Prize in Physics.

Early Life and Education

Chandrasekhar was born on 19 October 1910 in Lahore, then part of British India (now in Pakistan). He was the nephew of Sir C.V. Raman, Nobel laureate in Physics (1930). Demonstrating early academic brilliance, he pursued physics at Presidency College, Madras, and published his first scientific paper at the age of 19.
In 1930, he travelled to the United Kingdom as a Government of India scholar to study at the University of Cambridge under the guidance of Ralph H. Fowler. It was during this period, while en route to England, that Chandrasekhar began developing his theory of stellar structure, later known as the Chandrasekhar limit. He obtained his PhD in 1933 and subsequently worked at Cambridge and Harvard before settling at the University of Chicago, where he spent most of his career.

Scientific Contributions

The Chandrasekhar Limit

Chandrasekhar’s most celebrated discovery concerns the stability of white dwarf stars. He calculated that if the mass of a white dwarf exceeds approximately 1.4 times the mass of the Sun, electron degeneracy pressure would be insufficient to prevent gravitational collapse. Such stars would then evolve into neutron stars or black holes. This fundamental result revolutionised astrophysics by linking stellar mass to ultimate stellar fate.

Stellar Structure and Dynamics

He made groundbreaking contributions to the theory of stellar interiors, radiative transfer, and hydrodynamic stability. His work provided mathematical frameworks for understanding energy transport in stars, convection, and pulsations.

Compact Objects

Chandrasekhar advanced the theoretical study of neutron stars, black holes, and relativistic astrophysics. His later research on the mathematical theory of black holes included rigorous treatments of general relativity and stability analyses.

Broader Physics Contributions

Beyond astrophysics, Chandrasekhar also contributed to fluid dynamics, magnetohydrodynamics, and the kinetic theory of stellar systems. His writings extended into applied mathematics and theoretical physics, showcasing the breadth of his scholarship.

Major Works

Chandrasekhar authored several influential books that remain reference points in astrophysics:

• An Introduction to the Study of Stellar Structure (1939)
• Principles of Stellar Dynamics (1942)
• Radiative Transfer (1950)
• Hydrodynamic and Hydromagnetic Stability (1961)
• The Mathematical Theory of Black Holes (1983)

These works combined rigorous mathematics with physical insight, setting high standards for scientific exposition.

Academic Career

In 1937, Chandrasekhar joined the University of Chicago, where he worked for over six decades. He was associated with the Yerkes Observatory and later with the Enrico Fermi Institute. As a professor, he mentored numerous students and influenced generations of astrophysicists.
He also served as editor of The Astrophysical Journal for nearly two decades, significantly shaping the direction of astronomical research.

Recognition and Awards

Chandrasekhar received numerous honours during his lifetime, reflecting the global impact of his work:

• Nobel Prize in Physics (1983), shared with William A. Fowler, for studies on stellar structure and evolution.
• Royal Medal (1962) and Copley Medal (1984) of the Royal Society.
• National Medal of Science (1966) in the United States.
• Election to prestigious bodies including the Royal Society and the U.S. National Academy of Sciences.

Personal Life and Legacy

Chandrasekhar married Lalitha Doraiswamy in 1936, and the couple settled in the United States. Known for his modesty, discipline, and precision in both life and science, he maintained a deep interest in literature and the arts alongside his scientific pursuits.
He passed away on 21 August 1995 in Chicago, Illinois.