SN 2006gy
Encyclopedia
SN 2006gy was an extremely energetic supernova
, sometimes 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. On May 7, 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. Time magazine listed the discovery of SN 2006gy as third in its Top 10 Scientific Discoveries for 2007.
SN 2006gy occurred in a distant galaxy
(NGC 1260
), approximately 238 million light years
(72 megaparsec
s) away. Therefore, due to the time it took light from the supernova to reach Earth
, the event occurred about 238 million years ago. Preliminary indications are that it was an unusually high-energy supernova of a very large star
, around 150 solar mass
es (M⊙), possibly of a type referred to as a pair-instability supernova
. The kinetic energy released by the explosion has been estimated at 1052 erg
s (1045 J
).
A pair instability supernova can only happen in stars that are very massive— having a range of around 130 to 250 solar masses. At a certain point in such a massive star's life its core begins to produce high energy gamma rays which have a greater energy than the rest mass of two electron
s (mass-energy equivalence
). These high energy gamma rays strike atomic nuclei and are converted from energy (or heat) to matter, disrupting the equilibrium between thermodynamic pressure and gravity in the star's core. The sudden drop in thermodynamic pressure causes the core to collapse. As the core collapses it gets hotter and hotter until a runaway thermonuclear reaction begins. In a few seconds, all of the fuel in the core undergoes a cataclysmic thermonuclear fusion, blowing the star completely apart while leaving nothing behind.
Although the SN 2006gy supernova was intrinsically about one hundred times as luminous
as SN 1987A
, which was bright enough to be seen by the naked eye, SN 2006gy was more than 1,400 times as far away as SN 1987A, and too far away to be seen without a telescope
.
Denis Leahy and Rachid Ouyed, Canadian scientists from the University of Calgary
have proposed that SN 2006gy was the birth of a quark star
.
Another possibility is that SN 2006gy is not actually a pair-instability supernova but instead is powered by interaction with a dense circumstellar medium – a Type IIn supernova..
star located approximately 7,500 light years from Earth in the Milky Way
galaxy. Since Eta Carinæ is 32,000 times closer than SN2006gy, the light from it will be about a billion-fold brighter. It is estimated to be similar in size to the star which became SN2006gy. Dave Pooley, one of the discoverers of SN2006gy, says that if Eta Carinæ exploded in a similar fashion, it would be bright enough that one could read by its light here on Earth nights, and would even be visible during the day time. SN2006gy's Apparent magnitude
(m) is 15, so a similar event at Eta Carinæ will have an m of about -7.5. According to astrophysicist Mario Livio
, this could happen at any time, but the risk to life on Earth would be low.
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
, sometimes referred to as a hypernova
Hypernova
Hypernova , also known as a type 1c Supernova, refers to an incredibly large star that collapses at the end of its lifespan...
or quark-nova
Quark-nova
A quark-nova is a hypothetical type of supernova that could occur if a neutron star spontaneously collapsed to become a quark star. The concept of quark-novae was suggested by Dr. Rachid Ouyed and Drs. Dey and Dey...
, that was discovered on September 18, 2006. It was first observed by Robert Quimby
Robert Quimby
Robert Quimby is an American astronomer who received his Ph.D. in Astronomy from the University of Texas at Austin. As a lead member of the Texas Supernova Survey, Quimby and his team used the relatively small 18-inch ROTSE-IIIb robotic telescope on McDonald Observatory’s Mount Fowlkes, along with...
and P. Mondol, and then studied by several teams of astronomers using facilities that included the Chandra
Chandra X-ray Observatory
The Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the maximum mass for white dwarfs. "Chandra" also means "moon" or "luminous" in Sanskrit.Chandra...
, Lick
Lick Observatory
The Lick Observatory is an astronomical observatory, owned and operated by the University of California. It is situated on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, USA...
, and Keck Observatories. On May 7, 2007, NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
and several of the astronomers announced the first detailed analyses of the supernova, describing it as the "brightest stellar
Stellar
Stellar is an adjective referring to one or more stars. It may also refer to:* Hyundai Stellar, a car built by Hyundai Motor Company* "Stellar*", a New Zealand-based rock band.* "Stellar" , a song by Incubus...
explosion ever recorded". In October 2007 Quimby announced that SN 2005ap
SN 2005ap
SN 2005ap was an extremely energetic type II supernova. It is reported to be the brightest supernova yet recorded, twice as bright as the previous record holder, SN 2006gy...
had broken SN 2006gy's record as the brightest ever recorded supernova. Time magazine listed the discovery of SN 2006gy as third in its Top 10 Scientific Discoveries for 2007.
Characteristics
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
(NGC 1260
NGC 1260
NGC 1260 is a spiral galaxy in the constellation Perseus. In 2006, it was home to the second brightest object in the observable universe, supernova SN 2006gy.-External links:*...
), approximately 238 million light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
(72 megaparsec
Parsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
s) away. Therefore, due to the time it took light from the supernova to reach Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
, the event occurred about 238 million years ago. Preliminary indications are that it was an unusually high-energy supernova of a very large star
Hypergiant
A hypergiant is a star with a tremendous mass and luminosity, showing signs of a very high rate of mass loss.-Characteristics:...
, around 150 solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es (M⊙), possibly of a type referred to as a pair-instability supernova
Pair-instability supernova
A pair-instability supernova occurs when pair production, the production of free electrons and positrons in the collision between atomic nuclei and energetic gamma rays, reduces thermal pressure inside a supermassive star's core...
. The kinetic energy released by the explosion has been estimated at 1052 erg
Erg
An erg is the unit of energy and mechanical work in the centimetre-gram-second system of units, symbol "erg". Its name is derived from the Greek ergon, meaning "work"....
s (1045 J
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
).
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s (mass-energy equivalence
Mass-energy equivalence
In physics, mass–energy equivalence is the concept that the mass of a body is a measure of its energy content. In this concept, mass is a property of all energy, and energy is a property of all mass, and the two properties are connected by a constant...
). These high energy gamma rays strike atomic nuclei and are converted from energy (or heat) to matter, disrupting the equilibrium between thermodynamic pressure and gravity in the star's core. The sudden drop in thermodynamic pressure causes the core to collapse. As the core collapses it gets hotter and hotter until a runaway thermonuclear reaction begins. In a few seconds, all of the fuel in the core undergoes a cataclysmic thermonuclear fusion, blowing the star completely apart while leaving nothing behind.
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
as SN 1987A
SN 1987A
SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 51.4 kiloparsecs from Earth, approximately 168,000 light-years, close enough that it was visible to the naked eye. It could be seen from the Southern...
, which was bright enough to be seen by the naked eye, SN 2006gy was more than 1,400 times as far away as SN 1987A, and too far away to be seen without a telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...
.
Denis Leahy and Rachid Ouyed, Canadian scientists from the University of Calgary
University of Calgary
The University of Calgary is a public research university located in Calgary, Alberta, Canada. Founded in 1966 the U of C is composed of 14 faculties and more than 85 research institutes and centres.More than 25,000 undergraduate and 5,500 graduate students are currently...
have proposed that SN 2006gy was the birth of a quark star
Quark star
A quark star or strange star is a hypothetical type of exotic star composed of quark matter, or strange matter. These are ultra-dense phases of degenerate matter theorized to form inside particularly massive neutron stars....
.
Another possibility is that SN 2006gy is not actually a pair-instability supernova but instead is powered by interaction with a dense circumstellar medium – a Type IIn supernova..
Similarity to Eta Carinæ
Eta Carinæ (η Carinæ or η Car) is a highly luminous hypergiantHypergiant
A hypergiant is a star with a tremendous mass and luminosity, showing signs of a very high rate of mass loss.-Characteristics:...
star located approximately 7,500 light years from Earth in the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
galaxy. Since Eta Carinæ is 32,000 times closer than SN2006gy, the light from it will be about a billion-fold brighter. It is estimated to be similar in size to the star which became SN2006gy. Dave Pooley, one of the discoverers of SN2006gy, says that if Eta Carinæ exploded in a similar fashion, it would be bright enough that one could read by its light here on Earth nights, and would even be visible during the day time. SN2006gy's Apparent magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
(m) is 15, so a similar event at Eta Carinæ will have an m of about -7.5. According to astrophysicist Mario Livio
Mario Livio
Mario Livio is an astrophysicist and an author of works that popularize science and mathematics. He is currently an astronomer and head of public outreach at the Space Telescope Science Institute, which operates the Hubble Space Telescope...
, this could happen at any time, but the risk to life on Earth would be low.
External links
- Astronomy Picture of the Day 10 May 2007
- NASA's Chandra Sees Brightest Supernova Ever
- Workshop on First Stars III website (upcoming conference, links to prior papers)
- Giant exploding star outshines previous supernovas (CNN.com)
- Space.com article on SN 2006gy.
- Star dies in brightest supernova, BBC, Tuesday, 8 May 2007, 03:35 GMT
- The Greatest Show in Space, Time magazine Thursday, May 21st, 2007 Pages 56-57
- Supernova may offer new view of early universe
- Lick Observatory Laser Guide Star Adaptive Optics
- PAIRITEL (telescope) website
- Image SN 2006gy