The Chandrasekhar limit is the maximum mass of a stable white dwarf star. The currently accepted value of the Chandrasekhar limit is about 1.4 M☉ (2.765×1030 kg). The limit was named after Subrahmanyan Chandrasekhar.
A supernova is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed to form a diffuse nebula. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.
Stellar evolution is the process by which a star changes over the course of its lifetime and how it can lead to the creation of a new star. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the current age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star.
A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to Earth's. No nuclear fusion takes place in a white dwarf. Instead, the light it radiates comes from the residual heat stored in it. The nearest known white dwarf is Sirius B, at 8.6 light years, the smaller component of the Sirius binary star. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910. The name white dwarf was coined by Willem Jacob Luyten in 1922.
Subrahmanyan Chandrasekhar was an Indian-American theoretical physicist who made significant contributions to the scientific knowledge about the structure of stars, stellar evolution and black holes. He was awarded the 1983 Nobel Prize in physics along 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.
In astronomy, the term compact object refers collectively to white dwarfs, neutron stars, and black holes. It could also include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects have a high mass relative to their radius, giving them a very high density, compared to ordinary atomic matter.
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space–what they are, rather than where they are", which is studied in celestial mechanics.
Saul Perlmutter is a U.S. astrophysicist, a professor of physics at the University of California, Berkeley, where he holds the Franklin W. and Karen Weber Dabby Chair, and head of the International Supernova Cosmology Project at the Lawrence Berkeley National Laboratory. He is a member of both the American Academy of Arts & Sciences and the American Philosophical Society, and was elected a Fellow of the American Association for the Advancement of Science in 2003. He is also a member of the National Academy of Sciences. Perlmutter shared the 2006 Shaw Prize in Astronomy, the 2011 Nobel Prize in Physics, and the 2015 Breakthrough Prize in Fundamental Physics with Brian P. Schmidt and Adam Riess for providing evidence that the expansion of the universe is accelerating. Since 2021, he has been a member of the President’s Council of Advisors on Science and Technology (PCAST).
A Type Ia supernova is a type of supernova that occurs in binary systems in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white dwarf.
SN 2003fg, nicknamed the Champagne Supernova, was an unusual Type Ia supernova. It was discovered in 2003, with the Canada-France-Hawaii Telescope and the Keck Telescope, both on Mauna Kea in Hawaii, and announced by researchers at the University of Toronto. The supernova occurred in a galaxy some 4 billion light-years from Earth. It was nicknamed after the 1995 song "Champagne Supernova" by English rock band Oasis.
Thanu Padmanabhan was an Indian theoretical physicist and cosmologist whose research spanned a wide variety of topics in gravitation, structure formation in the universe and quantum gravity. He published nearly 300 papers and reviews in international journals and ten books in these areas. He made several contributions related to the analysis and modelling of dark energy in the universe and the interpretation of gravity as an emergent phenomenon. He was a Distinguished Professor at the Inter-University Centre for Astronomy and Astrophysics (IUCAA) at Pune, India.
A Type II supernova or SNII results from the rapid collapse and violent explosion of a massive star. A star must have at least eight times, but no more than 40 to 50 times, the mass of the Sun (M☉) to undergo this type of explosion. Type II supernovae are distinguished from other types of supernovae by the presence of hydrogen in their spectra. They are usually observed in the spiral arms of galaxies and in H II regions, but not in elliptical galaxies; those are generally composed of older, low-mass stars, with few of the young, very massive stars necessary to cause a supernova.
Sandip Chakrabarti is an Indian astrophysicist. He developed a computer model to show how life on earth could have originated in outer space.
p-nuclei (p stands for proton-rich) are certain proton-rich, naturally occurring isotopes of some elements between selenium and mercury inclusive which cannot be produced in either the s- or the r-process.
SN 2011fe, initially designated PTF 11kly, was a Type Ia supernova discovered by the Palomar Transient Factory (PTF) survey on 24 August 2011 during an automated review of images of the Messier 101 from the nights of 22 and 23 August 2011. It was located in Messier 101, the Pinwheel Galaxy, 21 million light years from Earth. It was observed by the PTF survey very near the beginning of its supernova event, when it was approximately 1 million times too dim to be visible to the naked eye. It is the youngest type Ia ever discovered. About 13 September 2011, it reached its maximum brightness of apparent magnitude +9.9 which equals an absolute magnitude of about -19, equal to 2.5 billion Suns. At +10 apparent magnitude around 5 September, SN 2011fe was visible in small telescopes. As of 30 September the supernova was at +11 apparent magnitude in the early evening sky after sunset above the northwest horizon. It had dropped to +13.7 as of 26 November 2011.
SN 1972E was a supernova in the galaxy NGC 5253 that was discovered 13 May 1972 with an apparent B magnitude of about 8.5, shortly after it had reached its maximum brightness. In terms of apparent brightness, it was the second-brightest supernova of any kind of the 20th century. It was observed for nearly 700 days, and it became the prototype object for the development of theoretical understanding of Type Ia supernovae.
Hen 2-428 is a planetary nebula with a binary double white dwarf system core. This core star system is the first discovered candidate for Type Ia supernova through binary white dwarf merger process. At the time of its discovery, the star system at the core was the heaviest known double white dwarf binary star system.
Edward M Sion is an American astrophysicist who is Professor in the Department of Astrophysics and Planetary Science at Villanova University. He specializes on the structure and evolution of white dwarf stars and white dwarf stars in explosive binary star systems known as cataclysmic variables.
Ken'ichi Nomoto is a Japanese astrophysicist and astronomer, known for his research on stellar evolution, supernovae, and the origin of heavy elements.
In the Chandrasekhar–Eddington dispute of the early 20th century, English astronomer Arthur Eddington and the Indian astronomer Subrahmanyan Chandrasekhar disagreed over the correct theory to describe the final stages of a star's lifecycle. During the dispute, Chandrasekhar was at the beginning of his career and Eddington was a renowned physicist of the time. Chandrasekhar had proposed a limit, now known as Chandrasekhar limit, indicating a maximum limit for the mass of a white dwarf star. In a series of conferences and encounters Eddington advocated for an alternative theory, openly criticizing and mocking Chandrasekhar's models.
