SN 2006gy was an extremely energetic supernova, also referred to as a

hypernova A hypernova (sometimes called a collapsar) is a very energetic supernova thought 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 energetic je ...

or quark-nova, that was discovered on September 18, 2006. It was first observed by Robert Quimby and P. Mondol,IAU Circular No. 8754
, accessed May 8, 2007 and then studied by several teams of

astronomers An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either obse ...

using facilities that included the

Chandra Chandra ( sa, चन्द्र, Candra, shining' or 'moon), also known as Soma ( sa, सोम), is the Hindu god of the Moon, and is associated with the night, plants and vegetation. He is one of the Navagraha (nine planets of Hinduism) a ...

, Lick, and Keck

Observatories An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...

. In May 2007

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...

and several of the astronomers announced the first detailed analyses of the supernova, describing it as the "brightest stellar explosion ever recorded".''NASA's Chandra Sees Brightest Supernova Ever''
NASA Press Release on the Discovery, May 7, 2007 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.

Characteristics

SN 2006gy occurred in a distant galaxy ( NGC 1260), approximately 238 million light-years (73

megaparsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

s) away. The energy radiated by the explosion has been estimated at 10⁵¹

erg The erg is a unit of energy equal to 10−7joules (100 nJ). It originated in the Centimetre–gram–second system of units (CGS). It has the symbol ''erg''. The erg is not an SI unit. Its name is derived from (), a Greek word meaning 'work' o ...

s (10⁴⁴ J), making it a hundred times more powerful than the typical supernova explosion which radiates 10⁴⁹ ergs (10⁴² J) of energy. Although at its peak the SN 2006gy supernova was intrinsically 400 times as luminous as

SN 1987A SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately from Earth and was the closest observed supernova since Kepler's Supernova. 1987A's light reached Earth on ...

, 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 A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observ ...

. SN 2006gy is classified as a

type II supernova A Type II supernova (plural: ''supernovae'' or ''supernovas'') results from the rapid collapse and violent explosion of a massive star. A star must have at least 8 times, but no more than 40 to 50 times, the mass of the Sun () to undergo th ...

because it showed lines of hydrogen in its spectrum, although the extreme brightness indicates that it is different from the typical type II supernova. Several possible mechanisms have been proposed for such a violent explosion, all requiring a very massive progenitor star. The most likely explanations involve the efficient conversion of explosive kinetic energy to radiation by interaction with circumstellar material, similar to a type IIn supernova but on a larger scale. Such a scenario might occur following mass loss of in a luminous blue variable eruption, or through pulsational pair instability ejections. Denis Leahy and Rachid Ouyed, Canadian scientists from the

University of Calgary The University of Calgary (U of C or UCalgary) is a public research university located in Calgary, Alberta, Canada. The University of Calgary started in 1944 as the Calgary branch of the University of Alberta, founded in 1908, prior to being ins ...

, have proposed that SN 2006gy was the birth of a

quark star 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. Background Some massive ...

Similarity to Eta Carinae

Eta Carinae Eta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around distant in th ...

(η Carinae or η Car) is a highly luminous

hypergiant A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term ''hypergiant'' is defined as luminosity class 0 (zero) in the MKK ...

star located approximately 7,500 light-years from Earth in the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...

galaxy. Since Eta Carinae is 32,000 times closer than SN 2006gy, the light from it will be about a billion-fold brighter. It is estimated to be similar in size to the star which became SN 2006gy. Dave Pooley, one of the discoverers of SN 2006gy, says that if Eta Carinae exploded in a similar fashion, it would be bright enough that one could read by its light on Earth at night, and would even be visible during the daytime. SN 2006gy's

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

(''m'') was 15, so a similar event at Eta Carinae will have an ''m'' of about −7.5. According to astrophysicist

Mario Livio Mario Livio (born June 19, 1945) is an Israeli-American astrophysicist and an author of works that popularize science and mathematics. For 24 years (1991-2015) he was an astrophysicist at the Space Telescope Science Institute, which operates th ...

, this could happen at any time, but the risk to life on Earth would be low.

References

SIMBAD data

External links

Light curves and spectra
on th
Open Supernova Catalog

10 May 2007

''Star dies in brightest supernova''
BBC, Tuesday, 8 May 2007, 03:35 GMT

* ttp://www.csmonitor.com/2007/0508/p01s04-usgn.html Supernova may offer new view of early universe
Lick Observatory Laser Guide Star Adaptive Optics

Image SN 2006gy
{{DEFAULTSORT:SN 2006gy Perseus (constellation) Supernovae Hypernovae 20060918