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215th Meeting of the American Astonomical Society, Washington DC : États-Unis (2010)
Nearby Supernova Factory Observations of SN 2007if: Evidence for Shell Structure in the Explosion of a Super-Chandrasekhar-Mass White Dwarf
R.A. Scalzo, C. Akerlof, G. Aldering, P. Antilogus1, C. Aragon, S. Bailey1, C. Baltay, A. Bauer, D. Birchall, S. Bongard1, C. Buton2, M. Childress, Y. Copin2, A. Gal-Yam, E. Gangler2, J. Holtzman, S. Hoyer, M. Kasliwal, S. Loken, J. Miller, P. Nugent, R. Pain1, E. Pecontal3, R. Pereira1, S. Perlmutter, C. S. Peters, R. Quimby, D. Rabinowitz, A. Rau, G. Rigaudier3, K. Runge, G. Smadja2, C. Tao4, R. C. Thomas, J. Thorstensen, B. Weaver, C. Wu1, F. Yuan

We present observations of SN 2007if, an overluminous (MV = -20.2 at peak), intrinsically red (B-V = 0.2 at peak), slow-rising (tR = 26 days) type Ia supernova in a very faint (Mg = -12) host galaxy. A spectrum taken at 5 days past B-band maximum light is a direct match to the super-Chandrasekhar candidate SN Ia 2003fg, showing a weak, slow Si II line at 9000 km/s and C II at higher velocities. SN 2007if also displays a plateau in the Si II velocity extending as late as 10 days after maximum light, which we interpret as evidence for an overdense shell in the SN ejecta. We calculate the bolometric light curve of the SN and use it and the Si II velocity evolution to constrain the mass of the shell and the underlying SN ejecta, and demonstrate that SN 2007if is strongly inconsistent with a Chandrasekhar-mass scenario. We discuss the implications for the emerging subclass of super-Chandrasekhar SNe Ia and for measurements of SN Ia luminosity distances.
1 :  LPNHE - Laboratoire de Physique Nucléaire et de Hautes Énergies
2 :  IPNL - Institut de Physique Nucléaire de Lyon
3 :  CRAL - Centre de Recherche Astrophysique de Lyon
4 :  CPPM - Centre de Physique des Particules de Marseille
Planète et Univers/Astrophysique/Astrophysique galactique

Physique/Astrophysique/Astrophysique galactique

Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique

Physique/Astrophysique/Cosmologie et astrophysique extra-galactique