The
Chandrasekhar limit is the maximum mass possible for a star, such that it remains a stable white dwarf star. It was named after
Subramanian Chandrasekhar, the Indian astrophysicist who predicted it in 1930. White dwarfs, unlike main sequence stars resist gravitational collapse primarily through electron degeneracy pressure, rather than thermal pressure. Main sequence stars are the central band of stars on the Hertzsprung-Russell diagram. The energy of these stars comes from the nuclear fusion. Most stars are main sequence stars which are also known as "dwarf stars". The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star’s core is insufficient to balance the star’s own gravitational self-attraction. So, the white dwarfs with masses greater than the limit undergo further gravitational collapse, evolving into a different type of stellar remnant, such as a neutron star or a black hole . Those with masses under the limit remain stable as white dwarfs. The currently accepted numerical value of the Chandrasekhar limit is about 1.4 solar masses or 2.85 * 10 30 Kg . Use of Chandrasekhar limit is fundamental in analyzing the evolution and demise of stars.
What is the History behind white dwarfs?
In 1926, the British physicist Ralph H. Fowler observed that the relationship between the density, energy and temperature of white dwarfs could be explained by viewing them as a gas of non-relativistic, non-interacting electrons and nuclei which obeyed Fermi-Dirac statistics. Fermi-Dirac statistics is a part of the science of physics that describes the energies of single particles in a system comprising many identical particles. This Fermi gas model was then used by the British physicist E.C. Stoner in 1926 to calculate the relationship between mass, radius, and density of white dwarfs, assuming them to be homogenous dwarfs. A series of papers published between 1931 and 1935 had its beginning on a trip from India to England in 1930, where the Indian Physicist Subramanian Chandrasekhar worked on the calculation of the statistics of a degenerate Fermi Gas. In these papers, Chandrasekhar solved the hydrostatic equation together with the non relativistic Fermi gas equation of state. Chandrasekhar reviewed this work in his Nobel Prize lecture. This value was also computed in 1932 by the Soviet physicist Lev Davidovinch Landau, who, however, did not apply it to the white dwarfs.
What is the Basic Principle of Chandrasekhar Limit?
The Chandrasekhar limit comes into play when the nuclear fuel in a star gets used up. Throughout the normal life time of a star, the outward pressure from nuclear reactions counteracts the contracting force of
gravity. Eventually, when the star has used up all its hydrogen fuel and departs from the main fusion sequence, the star fuses heavier and heavier nuclei until it lacks the temperature and density in its core to fuse anything more or the core turns to iron which is the heaviest fusion product that cannot itself be fused to produce more energy. Throughout the turbulent last few millions of years of their life, many stars eject most of their masses in the form of stellar wind, leaving behind a much smaller core. If the core has less mass than the
Chandrasekhar limit , it will form white dwarf, a body the size of Earth but with a mass similar to sun. If it has more mass than the Chandrasekhar limit , it will collapse to form a neutron star or black hole a process with the potential to initiate a core-collapse ‘Supernova’, which is the catastrophic death of a star characterized by a massive output of energy.
What is electron degeneracy pressure?
Electron degeneracy pressure is a result of the Pauli Exclusion Principle , which states that 2 fermions cannot occupy the same quantum state at the same time. The force provided by this pressure sets a limit on the extent to which matter can be squeezed together without collapsing it into a neutron star or a black hole . It is an important factor in stellar physics since it is responsible for the existence of white dwarfs.
Chandrasekhar limit is the maximum mass possible for a star, such that it remains a stable white dwarf star. It was named after
Subramanian Chandrasekhar, the Indian astrophysicist who predicted it in 1930. White dwarfs, unlike main sequence stars resist gravitational collapse primarily through electron degeneracy pressure, rather than thermal pressure. Main sequence stars are the central band of stars on the Hertzsprung-Russell diagram. The energy of these stars comes from the nuclear fusion. Most stars are main sequence stars which are also known as "dwarf stars". The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star’s core is insufficient to balance the star’s own gravitational self-attraction. So, the white dwarfs with masses greater than the limit undergo further gravitational collapse, evolving into a different type of stellar remnant, such as a neutron star or a black hole . Those with masses under the limit remain stable as white dwarfs. The currently accepted numerical value of the Chandrasekhar limit is about 1.4 solar masses or 2.85 * 10 30 Kg . Use of Chandrasekhar limit is fundamental in analyzing the evolution and demise of stars.
What is the History behind white dwarfs?
In 1926, the British physicist Ralph H. Fowler observed that the relationship between the density, energy and temperature of white dwarfs could be explained by viewing them as a gas of non-relativistic, non-interacting electrons and nuclei which obeyed Fermi-Dirac statistics. Fermi-Dirac statistics is a part of the science of physics that describes the energies of single particles in a system comprising many identical particles. This Fermi gas model was then used by the British physicist E.C. Stoner in 1926 to calculate the relationship between mass, radius, and density of white dwarfs, assuming them to be homogenous dwarfs. A series of papers published between 1931 and 1935 had its beginning on a trip from India to England in 1930, where the Indian Physicist Subramanian Chandrasekhar worked on the calculation of the statistics of a degenerate Fermi Gas. In these papers, Chandrasekhar solved the hydrostatic equation together with the non relativistic Fermi gas equation of state. Chandrasekhar reviewed this work in his Nobel Prize lecture. This value was also computed in 1932 by the Soviet physicist Lev Davidovinch Landau, who, however, did not apply it to the white dwarfs.
What is the Basic Principle of Chandrasekhar Limit?
The Chandrasekhar limit comes into play when the nuclear fuel in a star gets used up. Throughout the normal life time of a star, the outward pressure from nuclear reactions counteracts the contracting force of
gravity. Eventually, when the star has used up all its hydrogen fuel and departs from the main fusion sequence, the star fuses heavier and heavier nuclei until it lacks the temperature and density in its core to fuse anything more or the core turns to iron which is the heaviest fusion product that cannot itself be fused to produce more energy. Throughout the turbulent last few millions of years of their life, many stars eject most of their masses in the form of stellar wind, leaving behind a much smaller core. If the core has less mass than the
Chandrasekhar limit , it will form white dwarf, a body the size of Earth but with a mass similar to sun. If it has more mass than the Chandrasekhar limit , it will collapse to form a neutron star or black hole a process with the potential to initiate a core-collapse ‘Supernova’, which is the catastrophic death of a star characterized by a massive output of energy.
What is electron degeneracy pressure?
Electron degeneracy pressure is a result of the Pauli Exclusion Principle , which states that 2 fermions cannot occupy the same quantum state at the same time. The force provided by this pressure sets a limit on the extent to which matter can be squeezed together without collapsing it into a neutron star or a black hole . It is an important factor in stellar physics since it is responsible for the existence of white dwarfs.