SN 2008ax was a helium-rich type Ib core-collapse supernova in the interacting galaxy

NGC 4490 NGC 4490, also known as the Cocoon Galaxy, is a barred spiral galaxy in the constellation Canes Venatici. William Herschel discovered it in 1788. It is known to be of the closest interacting/merging galactic system. The galaxy lies at a distance o ...

. It was independently detected on 3 March 2008 by

LOSS Loss may refer to: Arts, entertainment, and media Music * ''Loss'' (Bass Communion album) (2006) * ''Loss'' (Mull Historical Society album) (2001) *"Loss", a song by God Is an Astronaut from their self-titled album (2008) * Losses "(Lil Tjay son ...

and 4 March by

Koichi Itagaki This is a list of minor-planet discoverers credited by the Minor Planet Center with the discovery of one or several minor planets (such as near-Earth object, near-Earth and main-belt asteroids, Jupiter trojans and Distant minor planet, distant obj ...

. The site had been monitored six hours before discovery, thus constraining the time of the explosion breakout. It was the third-brightest supernova of 2008. The brightness in the

B-band The NATO B band is the obsolete designation given to the radio frequencies from 250 to 500 MHz (equivalent to wavelengths between 1.20 and 0.60 m) during the cold war period. Since 1992 frequency allocations, allotment and assignments are in line ...

peaked about 20 days after the explosion. X-ray emissions were detected from the event, which are most likely the result of shock heating from the supernova ejecta and circumstellar material. Images of the source location made using the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

in 2011 and 2013 were used to identify the progenitor. If it was a single star, the images are compatible with a supergiant star with a class of B to mid-A type. However, this is not favored by models which indicate the progenitor had a relatively low mass of 4– and extended hydrogen-rich atmosphere with a radius of 30–. An alternative, more plausible model suggests the progenitor was part of an interacting binary system where much of the atmosphere was lost through mass transfer to the companion.

References

External links

Light curves and spectra
on th
Open Supernova Catalog
{{DEFAULTSORT:SN 2008ax Supernovae 20080303 Canes Venatici