SN 2005ap was an extremely energetic type Icsupernova in the galaxy SDSS J130115.12+274327.5. With a peak
absolute magnitude
Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...
of around −22.7, it is the second-brightest
superluminous supernova
A super-luminous supernova (SLSN, plural super luminous 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 mech ...
yet recorded, twice as bright as the previous record holder, SN 2006gy, though SN 2005ap was eventually surpassed by
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 dete ...
. 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 (Robotic Optical Transient Search Experiment) telescope, which is located at the
McDonald Observatory
McDonald Observatory is an astronomical observatory located near unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with additional faci ...
in
West Texas
West Texas is a loosely defined region in the U.S. state of Texas, generally encompassing the arid and semiarid lands west of a line drawn between the cities of Wichita Falls, Abilene, and Del Rio.
No consensus exists on the boundary betwee ...
Texas Supernova Search
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 dis ...
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
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
from Earth, it was not visible to the naked eye.
Although SN 2005ap was twice as bright at its peak than SN 2006gy, it was not as energetic overall, as the former brightened and dimmed in a typical period of a few days whereas the latter remained very bright for many months. SN 2005ap was about 300 times brighter than normal for a type II supernova. It has been speculated that this hypernova involved the formation 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 ...
. Quimby has suggested that the hypernova is of a new type distinct from the standard type II supernova, and his research group have identified five other supernovae similar to SN 2005ap and