* Astronomy

Title: A spectroscopically normal type Ic supernova from a very massive progenitor
Authors: Stefano Valenti (1), Stefan Taubenberger, Andrea Pastorello, Levon Aramyan, Maria Teresa Botticella, Morgan Fraser, Stefano Benetti, Stephen J. Smartt, Enrico Cappellaro, Nancy Elias-Rosa, Mattias Ergon, Lindsay Magill, Eugene Magnier, Rubina Kotak, Paul A. Price, Jesper Sollerman, Lina Tomasella, Massimo Turatto, Darryl Edmund Wright. - (1) INAF-Osservatorio Astronomico di Padova

We present observations of the Type Ic supernova (SN Ic) 2011bm spanning a period of about one year. The data establish that SN 2011bm is a spectroscopically normal SN Ic with moderately low ejecta velocities and with a very slow spectroscopic and photometric evolution (more than twice as slow as SN 1998bw). The Pan-STARRS1 retrospective detection shows that the rise time from explosion to peak was 40 days in the R band. Through an analysis of the light curve and the spectral sequence, we estimate a kinetic energy of 7-17 foe and a total ejected mass of 7-17 Mo, 5-10 Mo of which is oxygen and 0.6-0.7 Mo is 56Ni. The physical parameters obtained for SN 2011bm suggest that its progenitor was a massive star of initial mass 30-50 Mo. The profile of the forbidden oxygen lines in the nebular spectra show no evidence of a bi-polar geometry in the ejected material.

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