Nobel Prize-winning physicist who taught us what happens when stars die: Who is Subrahmanyan Chandrasekhar?

But not all stars collapse in the same way. Some turn into a supernova and then into neutron stars or black holes. We know all this from the work of astrophysicist Subrahmanyan Chandrasekhar.

Chandrasekhar won half of the 1983 Nobel Prize in Physics for his work. Their work represented one of the first and most important steps in our understanding of black holes and neutron stars. Before going into details, let's get to know him briefly.

Who is Subrahmanyan Chandrasekhar?

Born in Lahore on October 19, 1910, Subrahmanyan Chandrasekhar (Brief: Chandra) was the third of ten children born to a well-educated family. His mother was a translator who taught his children to read, and his father was the Deputy Auditor General of the Northwest Railroad.

Subrahmanyan Chandrasekhar (19 October 1910 – 21 August 1995)[4] was an Indian-American theoretical physicist who spent his professional life in the United States. He shared the 1983 Nobel Prize for Physics 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 yielded many of the current theoretical models of the later evolutionary stages of massive stars and black holes. Many concepts, institutions, and inventions, including the Chandrasekhar limit and the Chandra X-Ray Observatory, are named after him.

Nobel Prize-winning physicist C V Raman was his father's brother. He was homeschooled by his parents and private teachers until the age of 12. At the age of 14, he started his physics education in Madras, India.

It would soon become clear that he had extraordinary potential in physics. As a result, he was awarded a fellowship in 1930 at Cambridge University to pursue a doctorate in astrophysics. He would also calculate the maximum mass of a white dwarf that would win the Nobel prize while traveling by boat to England. He was only 19 when he did this job.

The name Sir Arthur Eddington is mostly remembered today for the Eddington experiment. Sir Arthur was a great astrophysicist. He was the first to experimentally confirm the bending of light by the sun, as predicted by Einstein's general relativity. But this was not Eddington's most important contribution to science. His work on stellar evolution is also extremely important. He was also the first to notice the young Subramanyan Chandrasekhar.

Chandrasekhar was a graduate student at Cambridge in the early thirties. His teacher, R H Fowler, was the first physicist to explain the evolution of stars with quantum theory. Chandrasekhar realized that when the mass of the stars in question became very large, the electrons in them could travel at speeds close to the speed of light.

He reorganized all of Fowler's work to take into account not only quantum theory but also Einstein's special relativity at such speeds. Eventually, he would find that once their masses exceeded a certain limit—the limit we now call the Chandrasekhar limit—the stars could no longer reach the final configuration proposed by Fowler.

Subrahmanyan Chandrasekhar's Discovery That Caused His Nobel Prize

Eddington was also interested in this business, and Subrahmanyan met often with Chandrasekhar to talk about it. In the process, he realized that if Chandrasekhar was right, some types of stars would collapse gravitationally and turn into black holes, an idea he had trouble accepting at the time. Eddington chose to believe that this graduate student must have been wrong. But Subrahmanyan Chandrasekhar was right.

Chandrasekhar was scheduled to present his theory to the Royal Society in London. Sir Arthur, a senior member of this respected society, made arrangements with the chairman of the meeting to deliver his own speech immediately after Chandra's. His goal was to prove that Chandra's ideas were absurd. A similar process would take place at a major international conference in Paris.

Chandra saw that he had no future in Europe and decided to attend the University of Chicago. As time passed, the inevitable validity of Chandra's discovery in 1931 became universally accepted, for which Chandra was awarded the 1983 Nobel Prize. This made Chandra the second Indian physicist to win a physics Nobel prize. The first was his uncle Venkata Raman, who won this award in 1930.

Before Chandrasekhar, scientists assumed that all stars turn into white dwarfs when they die. However, Chandrasekhar decided that was not the case.

What is a White Dwarf?

The faint star in the middle of the blue haze cloud is a white dwarf. NGC 2452 is located in the southern constellation of Puppis. Although not all white dwarfs have the same structure, they usually consist of three layers. The innermost one contains oxygen and carbon, a thin layer of helium in the middle, and a thin layer of hydrogen on the outside.

During the life of a star, the matter contained in the star is under the influence of two opposing forces. One of these is gravity, which pulls matter towards each other, forcing the star to collapse. The opposite force is the pressure of the gas heated by the high temperature, which is a byproduct of nuclear reactions in the star. As these two forces are in balance, the star shines steadily.

However, the star's nuclear fuel is limited. Burned hydrogen turns into helium, and the density of the core increases as the hydrogen decreases and the helium in the core increases. As central gravity dominates the gas pressure, the core of the star begins to collapse.

What is the Chandrasekhar Limit?

The hydrogen-burning layer, whose pressure is increasing, enters a very rapid combustion process, and this rapid reaction causes the outer layers of the star to expand. As the expanding gas cools, its temperature drops and it appears red. On the other hand, as the surface area increases, it emits approximately 1000 times more radiation than before.

Meanwhile, in the compressed core, helium reacts to form carbon. The layers above this core expand with the effect of radiation pressure, and then the star becomes a red giant. As the core collapses, the outer layers are released, and the core, which eventually runs out of nuclear fuel, becomes what is called a white dwarf.

In conclusion;

In the last years of his life, Chandrasekhar began working on the detailed geometrical arguments in Sir Isaac Newton's Philosophiae Naturalis Principia Mathematica, which is considered an important work in the history of science. He died of a heart attack on August 21, 1995.

In 1979, NASA named the third of the four Great Observatories after Chandrasekhar. Today, the Chandra X-ray observatory orbits the Earth. This observatory observes stars instead of Chandrasekhar.

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