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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.
SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately 51.4 kiloparsecs from Earth and was the closest observed supernova since Kepler's Supernova in 1604. Light and neutrinos from the explosion reached Earth on February 23, 1987; as the first supernova discovered that year, it was designated "SN 1987A". Its brightness peaked in May of that year, with an apparent magnitude of about 3.
A quark star is a hypothetical type of compact, exotic star, where extremely high core temperature and pressure has forced nuclear particles to form quark matter, a continuous state of matter consisting of free quarks.
A super-luminous supernova is a type of stellar explosion with a luminosity 10 or more times higher than that of standard supernovae. Like supernovae, SLSNe seem to be produced by several mechanisms, which is readily revealed by their light-curves and spectra. There are multiple models for what conditions may produce an SLSN, including core collapse in particularly massive stars, millisecond magnetars, interaction with circumstellar material, or pair-instability supernovae.
Messier 84 or M84, also known as NGC 4374, is a giant elliptical or lenticular galaxy in the constellation Virgo. Charles Messier discovered the object in 1781 in a systematic search for "nebulous objects" in the night sky. It is the 84th object in the Messier Catalogue and in the heavily populated core of the Virgo Cluster of galaxies, part of the local supercluster.
3C 58 or 3C58 is a pulsar and supernova remnant within the Milky Way. The object is listed as No. 58 in the Third Cambridge Catalogue of Radio Sources.
First observed between August 4 and August 6, 1181, Chinese and Japanese astronomers recorded the supernova now known as SN 1181 in eight separate texts. One of only five supernovae in the Milky Way confidently identified in pre-telescopic records, it appeared in the constellation Cassiopeia and was visible and motionless against the fixed stars for 185 days. F. R. Stephenson first recognized that the 1181 AD "guest star" must be a supernova, because such a bright transient that lasts for 185 days and does not move in the sky can only be a galactic supernova.
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.
The known history of supernova observation goes back to 1006 AD. All earlier proposals for supernova observations are speculations with many alternatives.
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.
SN 2006gy was an extremely energetic supernova, also referred to as a hypernova or quark-nova, that was discovered on September 18, 2006. It was first observed by Robert Quimby and P. Mondol, and then studied by several teams of astronomers using facilities that included the Chandra, Lick, and Keck Observatories. In May 2007 NASA and several of the astronomers announced the first detailed analyses of the supernova, describing it as the "brightest stellar explosion ever recorded". In October 2007 Quimby announced that SN 2005ap had broken SN 2006gy's record as the brightest-ever recorded supernova, and several subsequent discoveries are brighter still. Time magazine listed the discovery of SN 2006gy as third in its Top 10 Scientific Discoveries for 2007.
Gamma-ray burst progenitors are the types of celestial objects that can emit gamma-ray bursts (GRBs). GRBs show an extraordinary degree of diversity. They can last anywhere from a fraction of a second to many minutes. Bursts could have a single profile or oscillate wildly up and down in intensity, and their spectra are highly variable unlike other objects in space. The near complete lack of observational constraint led to a profusion of theories, including evaporating black holes, magnetic flares on white dwarfs, accretion of matter onto neutron stars, antimatter accretion, supernovae, hypernovae, and rapid extraction of rotational energy from supermassive black holes, among others.
RX J0822−4300, often referred to as a "Cosmic Cannonball", is a radio-quiet neutron star currently moving away from the center of the Puppis A supernova remnant at over 3 million miles per hour, making it one of the fastest moving stars ever found. Astronomers used NASA's Chandra X-ray Observatory to observe the star over a period of five years to determine its speed. At this velocity the star will be ejected from the galaxy millions of years from now.
SN 2005gj was a supernova located approximately 864 million light years away from Earth. It was discovered on September 29, 2005, by the Sloan Digital Sky Survey and the Nearby Supernova Factory. 2005gj was noted because it had qualities of both type Ia and type IIn supernovae, and because hydrogen emission lines were found in its spectrum. These hydrogen lines, which were found on the spectrum at redshift z=0.0613, are thought to be indicative of interactions with a circumstellar medium by the supernova's ejected matter or white dwarf progenitor. Such emission lines are extremely rare in Type Ia supernovae – only one other Type Ia, SN 2002ic, has been observed to exhibit the same properties. However, 2005gj's CSM interaction was much stronger and more clearly observed than 2002ic's. The mass-loss history 2005gj's hydrogen lines suggest has been cited as evidence that luminous blue variable (LBV) hypergiants can be progenitors of thermonuclear supernovae.
SN 393 is the modern designation for a probable supernova that was reported by the Chinese in the year 393 CE. An extracted record of this astronomical event was translated into English as follows:
A guest star appeared within the asterism Wěi during the second lunar month of the 18th year of the Tai-Yuan reign period, and disappeared during the ninth lunar month.
William David Arnett is a Regents Professor of Astrophysics at Steward Observatory, University of Arizona, known for his research on supernova explosions, the formation of neutron stars or black holes by gravitational collapse, and the synthesis of elements in stars; he is author of the monograph Supernovae and Nucleosynthesis which deals with these topics. Arnett pioneered the application of supercomputers to astrophysical problems, including neutrino radiation hydrodynamics, nuclear reaction networks, instabilities and explosions, supernova light curves, and turbulent convective flow in two and three dimensions.
James Michael Lattimer is a nuclear astrophysicist who works on the dense nuclear matter equation of state and neutron stars. He is currently a distinguished professor at Stony Brook University.
BAT99-98 is a star in the Large Magellanic Cloud. It is located near the R136 cluster in the 30 Doradus nebula. At 226 M☉ and 5,000,000 L☉ it is one of the most massive and luminous stars known.
A hypernova is a very energetic supernova which is believed to result from an extreme core-collapse scenario. In this case, a massive star collapses to form a rotating black hole emitting twin astrophysical jets and surrounded by an accretion disk. It is a type of stellar explosion that ejects material with an unusually high kinetic energy, an order of magnitude higher than most supernovae, with a luminosity at least 10 times greater. They usually appear similar to a type Ic supernova, but with unusually broad spectral lines indicating an extremely high expansion velocity. Hypernovae are one of the mechanisms for producing long gamma ray bursts (GRBs), which range from 2 seconds to over a minute in duration. They have also been referred to as superluminous supernovae, though that classification also includes other types of extremely luminous stellar explosions that have different origins.
References
- ↑ "Quark Nova Project" . Retrieved 13 Sep 2018.
- ↑ R. Ouyed; J. Dey; M. Dey (2002). "Quark-Nova". Astronomy and Astrophysics . 390 (3): L39–L42. arXiv: astro-ph/0105109 . Bibcode:2002A&A...390L..39O. doi:10.1051/0004-6361:20020982. S2CID 124427846.
- ↑ "Theories of Quark-novae". Archived from the original on October 7, 2012. Retrieved 11 Feb 2009.
- ↑ Prashanth Jaikumar; Meyer; Kaori Otsuki; Rachid Ouyed (2007). "Nucleosynthesis in neutron-rich ejecta from Quark-Novae". Astronomy and Astrophysics. 471 (1): 227–236. arXiv: nucl-th/0610013 . Bibcode:2007A&A...471..227J. doi:10.1051/0004-6361:20066593. S2CID 119093518.
- ↑ Astronomy Now Online - Second Supernovae Point to Quark Stars
- ↑ Leahy, Denis; Ouyed, Rachid (2008). "Supernova SN2006gy as a first ever Quark Nova?". Monthly Notices of the Royal Astronomical Society . 387 (3): 1193. arXiv: 0708.1787 . Bibcode:2008MNRAS.387.1193L. doi:10.1111/j.1365-2966.2008.13312.x. S2CID 15696112.
