Details

Autor(en) / Beteiligte

• Scalzo, R. A
• Aldering, G
• Antilogus, P
• Aragon, C
• Bailey, S
• Baltay, C
• Bongard, S
• Buton, C
• Childress, M
• Chotard, N
• Copin, Y
• Fakhouri, H. K
• Gal-Yam, A
• Gangler, E
• Hoyer, S
• Kasliwal, M
• Loken, S
• Nugent, P
• Pain, R
• Pécontal, E
• Pereira, R
• Perlmutter, S
• Rabinowitz, D
• Rau, A
• Rigaudier, G
• Runge, K
• Smadja, G
• Tao, C
• Thomas, R. C
• Weaver, B
• Wu, C

Titel

Nearby Supernova Factory Observations of SN 2007if: First Total Mass Measurement of a Super-Chandrasekhar-Mass Progenitor

Ist Teil von

• The Astrophysical journal, 2010-04, Vol.713 (2), p.1073-1094

Ort / Verlag

Bristol: IOP Publishing

Erscheinungsjahr

2010

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• We present photometric and spectroscopic observations of SN 2007if, an overluminous (M_V = -20.4), red (B-V = 0.16 at B-band maximum), slow-rising (t_rise = 24 days) type Ia supernova in a very faint (M_g = -14.10) host galaxy. A spectrum at 5 days past B-band maximum light is a direct match to the super-Chandrasekhar-mass candidate SN Ia 2003fg, showing Si II and C II at ~9000 km/s. A high signal-to-noise co-addition of the SN spectral time series reveals no Na I D absorption, suggesting negligible reddening in the host galaxy, and the late-time color evolution has the same slope as the Lira relation for normal SNe Ia. The ejecta appear to be well mixed, with no strong maximum in I-band and a diversity of iron-peak lines appearing in near-maximum-light spectra. SN2007 if also displays a plateau in the Si II velocity extending as late as +10 days, 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 \ion{Si}{2} velocity evolution to constrain the mass of the shell and the underlying SN ejecta, and demonstrate that SN2007 if is strongly inconsistent with a Chandrasekhar-mass scenario. Within the context of a "tamped detonation" model appropriate for double-degenerate mergers, and assuming no host extinction, we estimate the total mass of the system to be 2.4 +/- 0.2 solar masses, with 1.6 +/- 0.1 solar masses of nickel-56 and with 0.3-0.5 solar masses in the form of an envelope of unburned carbon/oxygen. Our modeling demonstrates that the kinematics of shell entrainment provide a more efficient mechanism than incomplete nuclear burning for producing the low velocities typical of super-Chandrasekhar-mass SNeIa.