The Indian physicist who ‘created’ a black hole
Subrahmanyan Chandrasekhar was known to the world as Chandra. The word chandra means “moon” or “luminous” in Sanskrit.
As a young doctoral student at Cambridge, Subramanian Chandrasekhar had deduced that certain types of stars, called white dwarfs, could not have a mass more than roughly 1.44 solar masses (the Chandrasekhar limit). If they exceeded this mass, they would undergo collapse under the pull of gravity. The collapse of a star exceeding the Chandrasekhar limit was a precursor to the idea of black holes.
When he presented his results in 1935 to the Royal Society, Britain’s most celebrated astronomer, Arthur Eddington (1882–1944) took violent objection on the grounds that Chandrasekhar had wrongly used quantum mechanics and that his proposed behavior for a star was simply absurd.
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Physicists knew Eddington’s argument to be incorrect, but did not come out in Chandrasekhar’s defense—some thought it obvious, and some were afraid to contradict Eddington. Chandrasekhar left England (where all doors were closed to him in view of the above) and migrated to the USA to become one of the most influential and respected astrophysicists in the world.
His results came to be universally accepted and he won the Nobel Prize in 1983, over 50 years after his great discovery.
Subrahmanyan Chandrasekhar, (born October 19, 1910, Lahore, India [now in Pakistan]—died August 21, 1995, Chicago, Illinois, U.S.) Indian-born American astrophysicist who, with William A. Fowler, 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.
Chandrasekhar was the nephew of Sir Chandrasekhara Venkata Raman, who won the Nobel Prize for Physics in 1930.
Chandrasekhar was educated at Presidency College, at the University of Madras, and at Trinity College, Cambridge. From 1933 to 1936 he held a position at Trinity.
By the early 1930s, scientists had concluded that, after converting all of their hydrogen to helium, stars lose energy and contract under the influence of their own gravity. These stars, known as white dwarf stars, contract to about the size of Earth, and the electrons and nuclei of their constituent atoms are compressed to a state of extremely high density. Chandrasekhar determined what is known as the Chandrasekhar limit—that a star having a mass more than 1.44 times that of the Sun does not form a white dwarf but instead continues to collapse, blows off its gaseous envelope in a supernova explosion, and becomes a neutron star. An even more massive star continues to collapse and becomes a black hole. These calculations contributed to the eventual understanding of supernovas, neutron stars, and black holes.
Chandrasekhar joined the staff of the University of Chicago, rising from assistant professor of astrophysics (1938) to Morton D. Hull distinguished service professor of astrophysics (1952), and became a U.S. citizen in 1953. He did important work on energy transfer by radiation in stellar atmospheres and convection on the solar surface. He also attempted to develop the mathematical theory of black holes, describing his work in The Mathematical Theory of Black Holes (1983).
Chandrasekhar was awarded the Gold Medal of the Royal Astronomical Society in 1953, the Royal Medal of the Royal Society in 1962, and the Copley Medal of the Royal Society in 1984. His other books include An Introduction to the Study of Stellar Structure (1939), Principles of Stellar Dynamics (1942), Radiative Transfer (1950), Hydrodynamic and Hydromagnetic Stability (1961), Truth and Beauty: Aesthetics and Motivations in Science (1987), and Newton’s Principia for the Common Reader (1995).
Subrahmanyan Chandrasekhar.
Subrahmanyan Chandrasekhar was born in 1910 in Lahore, which at the time was in British India. He was one of ten children born to Sita Balakrishnan and Chandrasekhara Subrahmanya Ayyar. His father was a government officer while his mother was a highly intellectual woman that translated literary works into Tamil, an Indian dialect. His parents and private tutors schooled Chandra at home until the age of twelve. He attended Hindu High School where he graduated in 1925 at the age of fifteen. He earned a bachelors degree in physics from Presidency College. Chandra received a scholarship to pursue graduate studies at Cambridge University in England. He also studied for one year in Copenhagen at the Institut for Teoretisk Fysik prior to receiving his Ph.D. from Cambridge in 1933. In 1936 Chandra was joined with Lalitha Doriswamy in a marriage that lasted for over fifty years. In 1937 Chandra joined the faculty of the University of Chicago where he remained until his death in 1995.
Subrahmanyan Chandrasekhar was one of the foremost astrophysicists of the twentieth century. He was one of the first scientists to couple the study of physics with the study of astronomy. Chandra proved that there was an upper limit to the mass of a white dwarf. This limit, known as the Chandra limit, showed that stars more massive than the Sun would explode or form black holes as they died. Chandra also developed theories on star atmospheres, black holes, the illumination of the sunlit sky, star structures and star mass. In 1983 Chandra was awarded the Nobel Prize in Physics for his work on the physical processes involved in the structure and evolution of stars. Chandra published ten books and served as the editor of the prominent Astrophysical Journal for nineteen years. In 1999, four years after his death in August of 1995, NASA launched Chandra, a x-ray observatory named in honor of Subrahmanyan Chandrasekhar.
The observatory studies the universe in the x-ray portion of the electromagnetic spectrum.
CHANDRASEKHAR LIMIT:
When a human puts on too much weight, there is an increased risk of
heart attack; when a white dwarf star puts on too much weight (i.e. adds
mass), there is the mother of all fatal heart attacks, a supernova
explosion. The greatest mass a white dwarf star can have before it goes
supernova is called the Chandrasekhar limit, after astrophysicist
Subrahmanyan Chandrasekhar, who worked it out in the 1930s. Its value is
approx 1.4 sols, or 1.4 times the mass of our Sun (the exact value
depends somewhat on the white dwarf’s composition how fast it’s
spinning, etc).
White dwarfs are the end of the road for most stars; once they have used up all their available hydrogen ‘fuel’, low mass stars shed their outermost shells to form planetary nebulae, leaving a high density core of carbon, oxygen, and nitrogen (that’s a summary, it’s actually a bit more complicated). The star can’t collapse further because of electron degeneracy pressure, a quantum effect that comes from the fact that electrons are fermions (technically, only two fermions can occupy a given energy state, one spin up and one spin down).
So what happens in the core of a massive star, one whose core weighs in at more than 1.4 sols? As long as the star is still ‘burning’ nuclear fuel – helium, then carbon etc, then neon, then … – the core will not collapse because it is very hot (electron degeneracy pressure won’t hold it up ’cause it’s too massive). But once the core gets to iron, no more burning is possible, and the core will collapse, spectacularly, producing a core collapse supernova.
There is a way a white dwarf can go out with a bang rather than a whimper; by getting a little help from a friend. If the white dwarf has a close binary companion, and if that companion is a giant star, some of the hydrogen in its outer shell may end up on the white dwarf’s surface (there are several ways this can happen). The white dwarf thus adds mass, and every so often the thin hydrogen envelope blows up, and we see a nova. One day, though, the extra mass may put it over the limit, the Chandrasekhar limit … the temperature in its center gets high enough that the carbon ‘ignites’, the ‘flame’ spreads throughout the star, and it becomes a special kind of supernova, a Ia supernova.
Source: Harvard
Image credit: David A. Aguilar
As a young doctoral student at Cambridge, Subramanian Chandrasekhar had deduced that certain types of stars, called white dwarfs, could not have a mass more than roughly 1.44 solar masses (the Chandrasekhar limit). If they exceeded this mass, they would undergo collapse under the pull of gravity. The collapse of a star exceeding the Chandrasekhar limit was a precursor to the idea of black holes.
When he presented his results in 1935 to the Royal Society, Britain’s most celebrated astronomer, Arthur Eddington (1882–1944) took violent objection on the grounds that Chandrasekhar had wrongly used quantum mechanics and that his proposed behavior for a star was simply absurd.
<div style="position:relative;height:0;padding-bottom:50%"><iframe src="https://www.youtube.com/embed/9f31wI6fClo?ecver=2" style="position:absolute;width:100%;height:100%;left:0" width="720" height="360" frameborder="0" allowfullscreen></iframe></div>
Physicists knew Eddington’s argument to be incorrect, but did not come out in Chandrasekhar’s defense—some thought it obvious, and some were afraid to contradict Eddington. Chandrasekhar left England (where all doors were closed to him in view of the above) and migrated to the USA to become one of the most influential and respected astrophysicists in the world.
His results came to be universally accepted and he won the Nobel Prize in 1983, over 50 years after his great discovery.
Subrahmanyan Chandrasekhar, (born October 19, 1910, Lahore, India [now in Pakistan]—died August 21, 1995, Chicago, Illinois, U.S.) Indian-born American astrophysicist who, with William A. Fowler, 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.
Chandrasekhar was the nephew of Sir Chandrasekhara Venkata Raman, who won the Nobel Prize for Physics in 1930.
Chandrasekhar was educated at Presidency College, at the University of Madras, and at Trinity College, Cambridge. From 1933 to 1936 he held a position at Trinity.
By the early 1930s, scientists had concluded that, after converting all of their hydrogen to helium, stars lose energy and contract under the influence of their own gravity. These stars, known as white dwarf stars, contract to about the size of Earth, and the electrons and nuclei of their constituent atoms are compressed to a state of extremely high density. Chandrasekhar determined what is known as the Chandrasekhar limit—that a star having a mass more than 1.44 times that of the Sun does not form a white dwarf but instead continues to collapse, blows off its gaseous envelope in a supernova explosion, and becomes a neutron star. An even more massive star continues to collapse and becomes a black hole. These calculations contributed to the eventual understanding of supernovas, neutron stars, and black holes.
Chandrasekhar joined the staff of the University of Chicago, rising from assistant professor of astrophysics (1938) to Morton D. Hull distinguished service professor of astrophysics (1952), and became a U.S. citizen in 1953. He did important work on energy transfer by radiation in stellar atmospheres and convection on the solar surface. He also attempted to develop the mathematical theory of black holes, describing his work in The Mathematical Theory of Black Holes (1983).
Chandrasekhar was awarded the Gold Medal of the Royal Astronomical Society in 1953, the Royal Medal of the Royal Society in 1962, and the Copley Medal of the Royal Society in 1984. His other books include An Introduction to the Study of Stellar Structure (1939), Principles of Stellar Dynamics (1942), Radiative Transfer (1950), Hydrodynamic and Hydromagnetic Stability (1961), Truth and Beauty: Aesthetics and Motivations in Science (1987), and Newton’s Principia for the Common Reader (1995).
Subrahmanyan Chandrasekhar.
Subrahmanyan Chandrasekhar was born in 1910 in Lahore, which at the time was in British India. He was one of ten children born to Sita Balakrishnan and Chandrasekhara Subrahmanya Ayyar. His father was a government officer while his mother was a highly intellectual woman that translated literary works into Tamil, an Indian dialect. His parents and private tutors schooled Chandra at home until the age of twelve. He attended Hindu High School where he graduated in 1925 at the age of fifteen. He earned a bachelors degree in physics from Presidency College. Chandra received a scholarship to pursue graduate studies at Cambridge University in England. He also studied for one year in Copenhagen at the Institut for Teoretisk Fysik prior to receiving his Ph.D. from Cambridge in 1933. In 1936 Chandra was joined with Lalitha Doriswamy in a marriage that lasted for over fifty years. In 1937 Chandra joined the faculty of the University of Chicago where he remained until his death in 1995.
Subrahmanyan Chandrasekhar was one of the foremost astrophysicists of the twentieth century. He was one of the first scientists to couple the study of physics with the study of astronomy. Chandra proved that there was an upper limit to the mass of a white dwarf. This limit, known as the Chandra limit, showed that stars more massive than the Sun would explode or form black holes as they died. Chandra also developed theories on star atmospheres, black holes, the illumination of the sunlit sky, star structures and star mass. In 1983 Chandra was awarded the Nobel Prize in Physics for his work on the physical processes involved in the structure and evolution of stars. Chandra published ten books and served as the editor of the prominent Astrophysical Journal for nineteen years. In 1999, four years after his death in August of 1995, NASA launched Chandra, a x-ray observatory named in honor of Subrahmanyan Chandrasekhar.
The observatory studies the universe in the x-ray portion of the electromagnetic spectrum.
Artist’s concept of gravitational wave propagation from the close orbit of two compact stars. Credit: R. Hurt: Caltech/JPL
CHANDRASEKHAR LIMIT:
Milky Way filled with ticking time bombs
When a human puts on too much weight, there is an increased risk of
heart attack; when a white dwarf star puts on too much weight (i.e. adds
mass), there is the mother of all fatal heart attacks, a supernova
explosion. The greatest mass a white dwarf star can have before it goes
supernova is called the Chandrasekhar limit, after astrophysicist
Subrahmanyan Chandrasekhar, who worked it out in the 1930s. Its value is
approx 1.4 sols, or 1.4 times the mass of our Sun (the exact value
depends somewhat on the white dwarf’s composition how fast it’s
spinning, etc).
White dwarfs are the end of the road for most stars; once they have used up all their available hydrogen ‘fuel’, low mass stars shed their outermost shells to form planetary nebulae, leaving a high density core of carbon, oxygen, and nitrogen (that’s a summary, it’s actually a bit more complicated). The star can’t collapse further because of electron degeneracy pressure, a quantum effect that comes from the fact that electrons are fermions (technically, only two fermions can occupy a given energy state, one spin up and one spin down).
So what happens in the core of a massive star, one whose core weighs in at more than 1.4 sols? As long as the star is still ‘burning’ nuclear fuel – helium, then carbon etc, then neon, then … – the core will not collapse because it is very hot (electron degeneracy pressure won’t hold it up ’cause it’s too massive). But once the core gets to iron, no more burning is possible, and the core will collapse, spectacularly, producing a core collapse supernova.
There is a way a white dwarf can go out with a bang rather than a whimper; by getting a little help from a friend. If the white dwarf has a close binary companion, and if that companion is a giant star, some of the hydrogen in its outer shell may end up on the white dwarf’s surface (there are several ways this can happen). The white dwarf thus adds mass, and every so often the thin hydrogen envelope blows up, and we see a nova. One day, though, the extra mass may put it over the limit, the Chandrasekhar limit … the temperature in its center gets high enough that the carbon ‘ignites’, the ‘flame’ spreads throughout the star, and it becomes a special kind of supernova, a Ia supernova.
Source: Harvard
Image credit: David A. Aguilar
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