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Hypernova
A hypernova is a very energetic supernova which is believed to result from an extreme core collapse scenario. In this case, a massive star (>30 solar masses) 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. Hypernovae release such intense gamma rays that they often 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 burst, 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. History In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SN 1998bw
SN 1998bw was a rare broad-lined Type Ic gamma ray burst supernova detected on 26 April 1998 in the spiral galaxy, which some astronomers believe may be an example of a collapsar ( hypernova). The hypernova has been linked to , which was detected on 25 April 1998, the first time a gamma-ray burst has been linked to a supernova. The hypernova is approximately 140 million light years away, very close for a gamma ray burst source. The region of the galaxy where the supernova occurred hosts stars 5-8 million years old and is relatively free from dust. A nearby region hosts multiple Wolf-Rayet stars less than 3 million years old, but it is unlikely that the supernova progenitor could be a runaway from that region. The implication is that the progenitor was a star that originally had a mass of , if it exploded as a single star at the end of its life. Observations On 25 April 1998, a gamma ray burst was detected by the BeppoSAX satellite and assigned the identifier GRB 98042 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supernova
A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, 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. The last supernova directly observed in the Milky Way was Kepler's Supernova in 1604, appearing not long after Tycho's Supernova in 1572, both of which were visible to the naked eye. The supernova remnant, remnants of more recent supernovae have been found, and observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. A supernova in the Milky Way would almost certainly be observable through mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Core Collapse Supernova
A supernova (: supernovae or supernovas) 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. The last supernova directly observed in the Milky Way was Kepler's Supernova in 1604, appearing not long after Tycho's Supernova in 1572, both of which were visible to the naked eye. The remnants of more recent supernovae have been found, and observations of supernovae in other galaxies suggest they occur in the Milky Way on average about three times every century. A supernova in the Milky Way would almost certainly be observable through modern astronomical telescopes. The m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Rays
A gamma ray, also known as gamma radiation (symbol ), is a penetrating form of electromagnetic radiation arising from high energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz () and wavelengths less than 10 picometers (), gamma ray photons have the highest photon energy of any form of electromagnetic radiation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation ''gamma rays'' based on their relatively strong penetration of matter; in 1900, he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power. Gamma rays from radioactive decay are in the energy range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pair-instability Supernova
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 hypergiant, supermassive star's core against gravitational collapse. This pressure drop leads to a partial collapse, which in turn causes greatly accelerated burning in a thermal runaway, runaway thermonuclear explosion, resulting in the star being blown completely apart without leaving a stellar remnant behind. Pair-instability supernovae can only happen in stars with a mass range from around 130 to 250 solar masses and low to moderate metallicity (low abundance of elements other than hydrogen and helium – a situation common in Population III stars). Physics Photon emission Photons given off by a body in thermal equilibrium have a Black-body radiation, black-body spectrum with an energy density proportional to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASASSN-15lh
ASASSN-15lh ( supernova designation SN 2015L) 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. The nature of ASASSN-15lh is disputed. The most popular explanations are that it is the most luminous type I supernova (hypernova) ever observed, or a tidal disruption event around a supermassive black hole. Other hypotheses include: gravitational lensing; a quark nova inside a Wolf–Rayet star; or a rapid magnetar spindown. Discovery A possible supernova was first noticed during an observat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bohdan Paczyński
Bohdan Paczyński or Bohdan Paczynski (8 February 1940 – 19 April 2007) was a Polish astronomer notable for his theories and work in the fields of stellar evolution, accretion discs, and gamma ray bursts. He is the recipient of the Eddington Medal (1987), the Henry Draper Medal (1997), the Gold Medal of the Royal Astronomical Society (1999), and the Order of Polonia Restituta (2007). Life and career Paczyński was born on 8 February 1940 in Vilnius, Lithuania, to a lawyer and a teacher of Polish literature. In 1945 his family chose to leave for Poland and settled in Kraków, and then in 1949 in Warsaw. At the age of 18, Paczyński published his first scientific article in ''Acta Astronomica''. Between 1959 and 1962 he studied astronomy at the University of Warsaw. Two years later he received a doctorate under the tutelage of Stefan Piotrowski and Włodzimierz Zonn. In 1962 Paczyński became a member of the Centre of Astronomy of the Polish Academy of Sciences, where he co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma-ray Bursts
In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme electromagnetic emissions are second only to the Big Bang as the most energetic and luminous phenomenon ever known. Gamma-ray bursts can last from a few milliseconds to several hours. After the initial flash of gamma rays, a longer-lived afterglow is emitted, usually in the longer wavelengths of X-ray, ultraviolet, optical, infrared, microwave or radio frequencies. The intense radiation of most observed GRBs is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole. Short-duration (sGRB) events are a subclass of GRB signals that are now known to originate from the cataclysmic merger of binary neutron stars. The sources of most GRB are billions of light years away from Earth, implying that the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superluminous Supernova
A superluminous supernova (SLSN, plural superluminous supernovae or SLSNe) 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 (CSM model), or pair-instability supernovae. The first confirmed superluminous supernova connected to a gamma ray burst was not found until 2003, when GRB 030329 illuminated the Leo constellation. SN 2003dh represented the death of a star 25 times more massive than the Sun, with material being blasted out at over a tenth the speed of light. Stars with are likely to produce superluminous supernovae. Classification Discoveries of many SLSNe in the 21st century showed that not only were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AT2021lwx
AT 2021lwx (also known as ZTF20abrbeie or "Scary Barbie") is the most energetic non-quasar optical transient astronomical event ever observed, with a peak luminosity of 7 × 1045 erg per second (erg s−1) and a total radiated energy between 9.7 × 1052 erg to 1.5 × 1053 erg over three years. Despite being lauded as the largest explosion ever, GRB 221009A was both more energetic and brighter. It was first identified in imagery obtained on 13 April 2021 by the Zwicky Transient Facility (ZTF) astronomical survey and is believed to be due to the accretion of matter into a super massive black hole (SMBH) heavier than one hundred million solar masses (). It has a redshift of z = 0.9945, which would place it at a distance of about eight billion light-years from earth, and is located in the constellation Vulpecula. No host galaxy has been detected. Forced photometry of earlier ZTF imagery showed AT 2021lwx had already begun brightening by 16 June 2020, as ZTF20abrbeie. It was al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Ray Burst
In gamma-ray astronomy, gamma-ray bursts (GRBs) are extremely energetic events occurring in distant galaxies which represent the brightest and most powerful class of explosion in the universe. These extreme electromagnetic emissions are second only to the Big Bang as the most energetic and luminous phenomenon ever known. Gamma-ray bursts can last from a few milliseconds to several hours. After the initial flash of gamma rays, a longer-lived afterglow is emitted, usually in the longer wavelengths of X-ray, ultraviolet, optical, infrared, microwave or radio frequencies. The intense radiation of most observed GRBs is thought to be released during a supernova or superluminous supernova as a high-mass star implodes to form a neutron star or a black hole. Short-duration (sGRB) events are a subclass of GRB signals that are now known to originate from the cataclysmic merger of binary neutron stars. The sources of most GRB are billions of light years away from Earth, implying that th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed Of Light
The speed of light in vacuum, commonly denoted , is a universal physical constant exactly equal to ). It is exact because, by international agreement, a metre is defined as the length of the path travelled by light in vacuum during a time interval of second. The speed of light is invariant (physics), the same for all observers, no matter their relative velocity. It is the upper limit for the speed at which Information#Physics_and_determinacy, information, matter, or energy can travel through Space#Relativity, space. All forms of electromagnetic radiation, including visible light, travel at the speed of light. For many practical purposes, light and other electromagnetic waves will appear to propagate instantaneously, but for long distances and sensitive measurements, their finite speed has noticeable effects. Much starlight viewed on Earth is from the distant past, allowing humans to study the history of the universe by viewing distant objects. When Data communication, comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
