* Astronomy

Blobrana · L

RE: Supernova 2005gl

Blobrana · L

Astronomers have detailed theories about what type of stars self-destruct in titanic supernova explosions. However, it would be useful to test stellar theory by actually seeing what a doomed star looked like before it blew apart. The problem is that a supernova blast pretty much eradicates all evidence of what the progenitor star was. Like a surveillance camera photographing the scene of a crime before it happened, the Hubble Space Telescope has a priceless archival photo of the galaxy that contains a picture of the supernova progenitor star as it appeared eight years before it exploded. The progenitor was comparatively easy to find because it was one of the brightest stars in the host galaxy. But the discovery has only further confounded supernova mysteries. The progenitor star belongs to a class of luminous blue variable stars that are not expected to explode at such an early stage of their existence.

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Blobrana · L

Title: On the progenitor of SN 2005gl and the nature of Type IIn supernovae
Authors: Avishay Gal-Yam (Caltech), D. C. Leonard (SDSU), D. B. Fox (PSU), S. B. Cenko (Caltech), A. M. Soderberg (Caltech), D.-S. Moon (Caltech), D. J. Sand (Steward), W. Li (UCB), A. V. Filippenko (UCB), G. Aldering (LBL), Y. Copin (IN2P3)

Researchers present a study of the type IIn supernova (SN) 2005gl, in the relatively nearby (d~66 Mpc) galaxy NGC 266. Photometry and spectroscopy of the SN indicate it is a typical member of its class.
Pre-explosion Hubble Space Telescope (HST) imaging of the location of the SN, along with a precise localisation of this event using the Laser-Guide-Star assisted Adaptive Optics (LGS-AO) system at Keck Observatory, are combined to identify a luminous (M_V=-10.3) point source as the possible progenitor of SN 2005gl. If the source is indeed a single star, it was likely a member of the class of luminous blue variable stars (LBVs). This finding leads the researchers to consider the possible general association of SNe IIn with LBV progenitors.
They find this is indeed supported by observations of other SNe, and the known properties of LBV stars. For example, they argue that should the prototypical Galactic LBV eta Carina explode in a phase similar to its current state, it will likely produce a type IIn SN. The researchers discuss their findings in the context of current ideas about the evolution of massive stars, and review the census of SNe with identified progenitors. They introduce the concept of the progenitor-SN map as a convenient means to discuss the present status and future prospects of direct searches for SN progenitors. The researchers conclude that this field has matured considerably in recent years, and the transition from anecdotal information about rare single events to robust associations of progenitor classes with specific SN types has already begun.