Spectroscopic observations of sn 2012fr: A luminous, normal type Ia supernova with early high-velocity features and a late velocity plateau

Childress, M.J. and Scalzo, R.A. and Sim, S.A. and Tucker, B.E. and Yuan, F. and Schmidt, B.P. and Cenko, S.B. and Silverman, J.M. and Contreras, C. and Hsiao, E.Y. and Phillips, M. and Morrell, N. and Jha, S.W. and McCully, C. and Filippenko, A.V. and Anderson, J.P. and Benetti, S. and Bufano, F. and de Jaeger, T. and Forster, F. and Gal-Yam, A. and Le Guillou, L. and Maguire, K. and Maund, J. and Mazzali, P.A. and Pignata, G. and Smartt, S. and Spyromilio, J. and Sullivan, M. and Taddia, F. and Valenti, S. and Bayliss, D.D.R. and Bessell, M. and Blanc, G.A. and Carson, D.J. and Clubb, K.I. and de Burgh-Day, C. and Desjardins, T.D. and Fang, J.J. and Fox, O.D. and Gates, E.L. and Ho, I.-T. and Keller, S. and Kelly, P.L. and Lidman, C. and Loaring, N.S. and Mould, J.R. and Owers, M. and Ozbilgen, S. and Pei, L. and Pickering, T. and Pracy, M.B. and Rich, J.A. and Schaefer, B.E. and Scott, N. and Stritzinger, M. and Vogt, F.P.A. and Zhou, G. ORCID: https://orcid.org/0000-0002-4891-3517 (2013) Spectroscopic observations of sn 2012fr: A luminous, normal type Ia supernova with early high-velocity features and a late velocity plateau. The Astrophysical Journal, 770 (1):29. pp. 1-20. ISSN 1538-4357

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We present 65 optical spectra of the Type Ia SN 2012fr, 33 of which were obtained before maximum light. At early times, SN 2012fr shows clear evidence of a high-velocity feature (HVF) in the Si lambda 6355 line that can be cleanly decoupled from the lower velocity 'photospheric' component. This Si lambda 6355 HVF fades by phase - 5; subsequently, the photospheric component exhibits a very narrow velocity width and remains at a nearly constant velocity of similar to 12,000 km s(-1) until at least five weeks after maximum brightness. The Ca II infrared triplet exhibits similar evidence for both a photospheric component at v approximate to 12,000 km s(-1) with narrow line width and long velocity plateau, as well as an HVF beginning at v approximate to 31,000 km s(-1) two weeks before maximum. SN 2012fr resides on the border between the 'shallow silicon' and 'core-normal' subclasses in the Branch et al. classification scheme, and on the border between normal and high-velocity Type Ia supernovae (SNe Ia) in the Wang et al. system. Though it is a clear member of the 'low velocity gradient' group of SNe Ia and exhibits a very slow light-curve decline, it shows key dissimilarities with the overluminous SN 1991T or SN 1999aa subclasses of SNe Ia. SN 2012fr represents a well-observed SN Ia at the luminous end of the normal SN Ia distribution and a key transitional event between nominal spectroscopic subclasses of SNe Ia.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 11 Jan 2022 03:05
Last Modified: 07 Feb 2022 04:55
Uncontrolled Keywords: galaxies: individual (NGC 1365); supernovae: general; supernovae: individual (SN 2012fr)
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.1093/mnras/stt813
URI: http://eprints.usq.edu.au/id/eprint/44986

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