Analysis of the Early-time Optical Spectra of SN 2011fe in M101

Journal article
Venue Astrophysical Journal Letters Date June 2012 DOI 10.1088/2041-8205/752/2/L26
J. T. Parrent, D. A. Howell, B. Friesen, R. C. Thomas, R. A. Fesen, D. Milisavljevic, F. B. Bianco, B. Dilday, P. Nugent, E. Baron … J. Bloom … +27 moreShow fewer
J. T. Parrent, D. A. Howell, B. Friesen, R. C. Thomas, R. A. Fesen, D. Milisavljevic, F. B. Bianco, B. Dilday, P. Nugent, E. Baron, I. Arcavi, S. Ben-Ami, D. Bersier, L. Bildsten, J. Bloom, Y. Cao, S. B. Cenko, A. V. Filippenko, A. Gal-Yam, M. M. Kasliwal, N. Konidaris, S. R. Kulkarni, N. M. Law, D. Levitan, K. Maguire, P. A. Mazzali, E. O. Ofek, Y. Pan, D. Polishook, D. Poznanski, R. M. Quimby, J. M. Silverman, A. Sternberg, M. Sullivan, E. S. Walker, Dong Xu, C. Buton, R. Pereira

Abstract

The nearby Type Ia supernova (SN Ia) SN 2011fe in M101 (cz = 241 km s$^-1$) provides a unique opportunity to study the early evolution of a ``normal’’ SN Ia, its compositional structure, and its elusive progenitor system. We present 18 high signal-to- noise spectra of SN 2011fe during its first month beginning 1.2 days post-explosion and with an average cadence of 1.8 days. This gives a clear picture of how various line-forming species are distributed within the outer layers of the ejecta, including that of unburned material (C+O). We follow the evolution of C II absorption features until they diminish near maximum light, showing overlapping regions of burned and unburned material between ejection velocities of 10,000 and 16,000 km s$^-1$. This supports the notion that incomplete burning, in addition to progenitor scenarios, is a relevant source of spectroscopic diversity among SNe Ia. The observed evolution of the highly Doppler-shifted O I łambda7774 absorption features detected within 5 days post-explosion indicates the presence of O I with expansion velocities from 11,500 to 21,000 km s$^-1$. The fact that some O I is present above C II suggests that SN 2011fe may have had an appreciable amount of unburned oxygen within the outer layers of the ejecta.

supernovae: general supernovae: individual: SN 2011fe Astrophysics - Cosmology and Nongalactic Astrophysics Astrophysics - Solar and Stellar Astrophysics

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