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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.
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.
SN 1006 was a supernova that is likely the brightest observed stellar event in recorded history, reaching an estimated −7.5 visual magnitude, and exceeding roughly sixteen times the brightness of Venus. Appearing between April 30 and May 1, 1006, in the constellation of Lupus, this "guest star" was described by observers across China, Japan, modern-day Iraq, Egypt, and Europe, and was possibly recorded in North American petroglyphs. Some reports state it was clearly visible in the daytime. Modern astronomers now consider its distance from Earth to be about 7,200 light-years or 2,200 parsecs.
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.
A pair-instability supernova is a type of supernova predicted to occur when pair production, the production of free electrons and positrons in the collision between atomic nuclei and energetic gamma rays, temporarily reduces the internal radiation pressure supporting a supermassive star's core against gravitational collapse. This pressure drop leads to a partial collapse, which in turn causes greatly accelerated burning in a runaway thermonuclear explosion, resulting in the star being blown completely apart without leaving a stellar remnant behind.
SN 2005ap was an extremely energetic type Ic supernova in the galaxy SDSS J130115.12+274327.5. With a peak absolute magnitude of around −22.7, it is the second-brightest superluminous supernova yet recorded, twice as bright as the previous record holder, SN 2006gy, though SN 2005ap was eventually surpassed by ASASSN-15lh. It was initially classified as type II-L, but later revised to type Ic. It was discovered on 3 March 2005, on unfiltered optical images taken with the 0.45 m ROTSE-IIIb telescope, which is located at the McDonald Observatory in West Texas, by Robert Quimby, as part of the Texas Supernova Search that also discovered SN 2006gy. Although it was discovered before SN 2006gy, it was not recognized as being brighter until October 2007. As it occurred 4.7 billion light years from Earth, it was not visible to the naked eye.
Texas Supernova Search (TSS) is one of many ongoing projects to identify and record supernova events. The project is led by Robert Quimby and to date has found 35 supernovae, 29 of which they were the first to report on. In addition they have discovered twelve (extragalactic) novae and six dwarf novae.
Supernova impostors are stellar explosions that appear at first to be a supernova but do not destroy their progenitor stars. As such, they are a class of extra-powerful novae. They are also known as Type V supernovae, Eta Carinae analogs, and giant eruptions of luminous blue variables (LBV).
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 2011dh was a supernova in the Whirlpool Galaxy (M51). It was discovered on 31 May 2011, with an apparent magnitude 13.5. and confirmed by several sources, including the Palomar Transient Factory. A candidate progenitor was detected in Hubble Space Telescope images. The progenitor may have been a highly luminous yellow supergiant with an initial mass of 18-24 solar masses. The supernova peaked near apparent magnitude 12.1 on 19 June 2011. Emission spectra indicated that the explosion was a type II supernova, in which a massive star collapses once nuclear fusion has ceased in its core.
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 2213-1745 was an extremely remote superluminous supernova (SLSN), which occurred in between November 2004 and June 2005. Its peak far-ultraviolet absolute magnitude reached −21.2, which was comparable to the total absolute magnitude of its host galaxy. The distance (redshift) to this supernova z=2.0458±0.0005 makes it one of the most remote supernova observed as of 2012. The luminosity of SN 2213-1745 evolved slowly over several years as it was still detectable in November 2006. Both the high luminosity and slow decay indicate that the supernova's progenitor was a star with an initial mass as high as 250 solar masses. The supernova explosion itself was likely a pair-instability supernova similar to the SN 2007bi event, with which it shares many similarities.
SN 1000+0216 was an extremely remote superluminous supernova (SLSN), which occurred in between June and November 2006 in the constellation Sextans. Its peak far-ultraviolet absolute magnitude reached −21.5, which exceeded the total absolute magnitude of its host galaxy. The distance (redshift) to this supernova z=3.8993 ± 0.0074 makes it the most distant supernova observed as of 2012. The luminosity of SN 1000+0216 evolved slowly over several years as it was still detectable in November 2008. Both the high luminosity and slow decay indicate that the supernova's progenitor was a very massive star. The supernova explosion itself was likely either a pair-instability supernova or a pulsational pair-instability supernova similar to the SN 2007bi event. It also had some similarities to the low redshift SN 2006gy supernova. Overall classification of SN 1000+0216 remains uncertain.
ASASSN-15lh is an extremely luminous astronomical transient event discovered by the All Sky Automated Survey for SuperNovae (ASAS-SN), with the appearance of a superluminous supernova event. It was first detected on June 14, 2015, located within a faint galaxy in the southern constellation Indus, and was the most luminous supernova-like object ever observed. At its peak, ASASSN-15lh was 570 billion times brighter than the Sun, and 20 times brighter than the combined light emitted by the Milky Way Galaxy. The emitted energy was exceeded by PS1-10adi.
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.
PS1-10adi is an unusual kind of highly energetic optical transient discovered by the Pan-STARRS survey on 15 August 2010. The explosion or transient event emitted 2.3×1052 ergs (2.3×1045 Joules), exceeding ASASSN-15lh. It may be a superluminous supernova or a stellar disruption event. The magnitude of the explosion challenges the limits of the current models for theoretical physics.
References
- 1 2 3 Chornock, R.; et al. (March 2016). "Spectroscopic classification of two superluminous supernovae". The Astronomer's Telegram. 8790: 1. Bibcode:2016ATel.8790....1C.
- ↑ Irving, Michael (2020-04-14). "Astronomers spot the brightest and most energetic supernova on record". New Atlas. Retrieved 2023-10-10.
- ↑ Crane, Leah (2020-04-13). "Astronomers have spotted the most powerful supernova ever". New Scientist. Retrieved 2023-10-04.
- ↑ Carpineti, Alfredo (2020-04-13). "Astronomers Catch The Brightest Supernova Ever Seen". IFLScience. Retrieved 2023-10-11.
- ↑ Nicholl, Matt; Blanchard, Peter K.; Berger, Edo; Chornock, Ryan; Margutti, Raffaella; Gomez, Sebastian; Lunnan, Ragnild; Miller, Adam A.; Fong, Wen-fai; Vigna-Gómez, Alejandro; Bhirombhakdi, Kornpob; Bieryla, Allyson; Challis, Pete; Laher, Russ R.; Masci, Frank J.; Paterson, Kerry (13 April 2020). "An extremely energetic supernova from a very massive star in a dense medium". Nature Astronomy. 4 (9): 893–899. arXiv: 2004.05840 . Bibcode:2020NatAs...4..893N. doi:10.1038/s41550-020-1066-7. S2CID 215744925 . Retrieved 13 April 2020.
- ↑ "AT 2016aps". Transient Name Server. 25 February 2016. Retrieved 14 April 2020.
- 1 2 Wall, Mike (13 April 2020). "Boom! Distant star explosion is brightest ever seen". Space.com. Retrieved 13 April 2020.
- ↑ "Supernova PS16aqy" . Retrieved 28 April 2020.
- ↑ "Photometrie for SN2016aps". The Open Supernova Catalog. James Guillochon and Jerod Parrent. Archived from the original on 2020-04-19. Retrieved 2020-04-15.
- ↑ Rogers, Kristen (13 April 2020). "Astronomers just discovered the brightest supernova ever seen". CNN. Retrieved 14 April 2020.
- ↑ Starr, Michelle (14 April 2020). "Astronomers Detect The Most Powerful Star Explosion We've Ever Observed". Science Alert. Retrieved 15 April 2020.
