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

Authors

M. J. Childress, The Australian National University
R. A. Scalzo, The Australian National University
S. A. Sim, The Australian National University
B. E. Tucker, The Australian National University
F. Yuan, The Australian National University
B. P. Schmidt, The Australian National University
S. B. Cenko, University of California, Berkeley
J. M. Silverman, The University of Texas at Austin
C. Contreras, Las Campanas Observatory
E. Y. Hsiao, Las Campanas Observatory
M. Phillips, Las Campanas Observatory
N. Morrell, Las Campanas Observatory
S. W. Jha, Rutgers University–New Brunswick
C. McCully, Rutgers University–New Brunswick
A. V. Filippenko, University of California, Berkeley
J. P. Anderson, Universidad de Chile
S. Benetti, Osservatorio Astronomico di Padova
F. Bufano, Universidad Andrés Bello
T. De Jaeger, Universidad de Chile
F. Forster, Universidad de Chile
A. Gal-Yam, Weizmann Institute of Science Israel
L. Le Guillou, Sorbonne Universite
K. Maguire, University of Oxford
J. Maund, Queen's University Belfast
P. A. Mazzali, Osservatorio Astronomico di Padova
G. Pignata, Universidad Andrés Bello
S. Smartt, Queen's University Belfast
J. Spyromilio, European Southern Observatory
M. Sullivan, University of Southampton
F. Taddia, Stockholms universitet
S. Valenti, Las Cumbres Observatory Global Telescope Network, Inc
D. D.R. Bayliss, The Australian National University
M. Bessell, The Australian National University

Document Type

Article

Publication Date

6-10-2013

Abstract

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 II λ6355 line that can be cleanly decoupled from the lower velocity "photospheric" component. This Si II λ6355 HVF fades by phase -5; subsequently, the photospheric component exhibits a very narrow velocity width and remains at a nearly constant velocity of 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 12,000 km s-1 with narrow line width and long velocity plateau, as well as an HVF beginning at v 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. © 2013. The American Astronomical Society. All rights reserved..

Publication Source (Journal or Book title)

Astrophysical Journal

Recommended Citation

Childress, M., Scalzo, R., Sim, S., Tucker, B., Yuan, F., Schmidt, B., Cenko, S., Silverman, J., Contreras, C., Hsiao, E., Phillips, M., Morrell, N., Jha, S., McCully, C., Filippenko, A., Anderson, J., Benetti, S., Bufano, F., De Jaeger, T., Forster, F., Gal-Yam, A., Le Guillou, L., Maguire, K., Maund, J., Mazzali, P., Pignata, G., Smartt, S., Spyromilio, J., Sullivan, M., Taddia, F., Valenti, S., Bayliss, D., & Bessell, M. (2013). Spectroscopic observations of sn 2012fr: A luminous, normal type ia supernova with early high-velocity features and a late velocity plateau. Astrophysical Journal, 770 (1) https://doi.org/10.1088/0004-637X/770/1/29