SN 2006gy
SN 2006gy is a supernova that was discovered on September 18, 2006 as part of the Texas Supernova Search program (University of Berkeley, California, team led by Nathan Smith). Located in the galaxy NGC 1260 , which is about 73 Mpc (about 238 million light-years ) away, it is currently classified as a Type IIb supernova due to weak hydrogen lines .
However, SN 2006gy differs significantly from other supernovae: The previously known supernovae have absolute brightnesses of around −16 to −20.5 magnitudes (mag), with the most luminous ones reaching their maximum around 20 days after discovery - SN 2006gy, on the other hand, has one Luminosity of −22 mag more than one magnitude more luminous and thus, measured by the absolute brightness , the second brightest known supernova at this point in time after SN 2005ap (M = −22.7 mag); in addition, the brightness was about 100 days above −21 mag and the maximum was only reached 70 days after discovery.
Possible explosion mechanisms
The mechanism behind the explosion has not yet been clarified. The following theories are currently being discussed:
Extremely massive precursor star
According to the interpretation of the discovery team, the forerunner star can only be a very massive star: According to the most plausible scenario to date, in which a large part of the luminosity comes from the decay of 56 Ni (decay chain: 56 Ni → 56 Co → 56 Fe), the order of magnitude would be around 20 Solar masses of 56 Ni required (for the mechanism of the fusion reactions see under nucleosynthesis ); typical amounts of nickel , however, in the case of a type II supernova and a stellar mass between 15 and 20 solar masses, are around 0.07 solar masses and thus more than two orders of magnitude less - the precursor star must have been significantly heavier.
Pair instability supernova
The team of explorers also speaks of the possibility that the precursor star could have been a luminous blue variable (LBV) similar to η Car , which was completely torn apart by a pair instability. Although this hypothesis seems to fit very well with the previously known data of the supernova, it contradicts several common ideas of modern astrophysics :
- Supernovae triggered by pair instability (PISN) have been the subject of theoretical investigations since the 1980s, but they are only believed to be possible in the early phase of the universe in the first generation of stars with a redshift of z = 15 to z = 30: for a PISN is according to the present Model calculations require a helium nucleus of 64 to 133 solar masses, corresponding to a mass of the forerunner star of around 140 to 260 solar masses (without taking the loss of mass into account) - only in the early phase of the universe are such massive stars possible, which is why there are no theoretical studies on one possible pair instability in stars of solar metallicity .
- Since Luminous Blue Variables are very massive stars that have not yet shed their hydrogen shell, they are regarded as precursors of the Wolf-Rayet stars and not as direct precursors of a supernova - however, other supernovae of the IIn type also show evidence on an LBV forerunner.
Quark Nova
Another possible scenario suggested by Denis Leahy and Rachid Ouyed from the University of Calgary was a two-stage collapse first into a neutron star and then into a quark star . According to this hypothesis, during the formation of the quark star and the associated transformation of matter into strange matter, enough energy is released to generate a second, faster shock wave from the outer layers of the neutron star, which collides with the layers that were first repelled during the supernova so the immense luminosity of this supernova is generated. The theory of the quark nova has been controversial in specialist circles.
See also
literature
- Smith, Li, Foley, Wheeler, et al .: SN 2006gy: Discovery of the most luminous supernova ever recorded, powered by the death of an extremely massive star like Eta Carinae . Astrophysical Journal , arxiv : astro-ph / 0612617
Web links
- Wissenschaft.de: Record - researchers observe brightest supernova May 10, 2007
- Spektrum .de: White dwarf died in the arms of his partner January 23, 2020
Individual evidence
- ↑ Gal-Yam, Leonard; Fox, Cenko et al .: On the Progenitor of SN 2005gl and the Nature of Type I In Supernovae . The Astrophysical Journal, 656, Issue 1, pp. 372-381, 02/2007 ( arxiv : astro-ph / 0608029 ).
- ↑ Leahy, Denis; Ouyed, Rachid: Supernova SN2006gy as a first ever Quark Nova? 08/2007, arxiv : 0708.1787
- ^ New Scientist : What the brightest supernova the birth of a quark star? ( Memento of the original from August 22, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (August 20, 2007)
