| Abstract |
SN 2007bi was discovered as an extremely luminous Type Ic supernova (SN). From the observations of the light curve and spectral analysis, this SN was proposed as a pair-instability SN with a ~ 100 M_solar. On the other hand, these observational features were also reproduced by a core-collapse SN model with a ~ 40 M_solar progenitor. Therefore, the explosion mechanism of this SN has not been identified.We calculated the evolution and mass loss of very massive stars with the main-sequence mass of 100-500 M_solar and the metallicity corresponding to the host galaxy of SN 2007bi. The evolution from the main-sequence stage until the central He exhaustion was calculated. We took into account the uncertainties of the mass loss rate. Then, we evaluate the range of the main-sequence mass of very massive stars appropriate for the progenitor of SN 2007bi to discuss the possibility of the explosion mechanism of SN 2007bi.The main-sequence mass of the progenitor exploding as a pair-instability SN corresponding to SN 2007bi was evaluated to be 515-575 M_solar. The minimum main-sequence mass is 310 M_solar when the uncertainties of the mass loss rate are taken into account. The main-sequence mass of the progenitor appropriate for a core-collapse SN is 110-280 M_solar. Taking into account Salpeter initial mass function, the argument of the explosion mechanism of SN 2007bi favors a core-collapse SN. In this talk, I will also show details of the evolution and mass loss of these massive stars. |
