1998/06/30 by K. Iwamoto, P. A. Mazzali, K. Nomoto +24 · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1038/27155
published as Nature 395 (1998) 672-674 · to appear in Nature(accepted July 27; submitted June 11, 1998)
arxiv created 1998/08/06 · arxiv updated 2009/12/01
The discovery of the peculiar supernova (SN) 1998bw and its possible association with the gamma-ray burst (GRB) 9804251,2,3 provide new clues to the understanding of the explosion mechanism of very massive stars and to the origin of some classes of gamma-ray bursts. Its spectra indicate that SN~1998bw is a type Ic supernova3,4, but its peak luminosity is unusually high compared with typical type Ic supernovae3. Here we report our findings that the optical spectra and the light curve of SN 1998bw can be well reproduced by an extremely energetic explosion of a massive carbon+oxygen (C+O) star. The kinetic energy is as large as ∼ 2-5 × 1052 ergs, more than ten times the previously known energy of supernovae. For this reason, the explosion may be called a `hypernova'. Such a C+O star is the stripped core of a very massive star that has lost its H and He envelopes. The extremely large energy, suggesting the existence of a new mechanism of massive star explosion, can cause a relativistic shock that may be linked to the gamma-ray burst.