SPECTROSCOPIC OBSERVATIONS OF SN 2012fr: A LUMINOUS, NORMAL TYPE Ia SUPERNOVA WITH EARLY HIGH-VELOCITY FEATURES AND A LATE VELOCITY PLATEAU

Journal Article · Mon Jun 10 00:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/770/1/29· OSTI ID:22127164

Childress, M. J.; Scalzo, R. A.; Sim, S. A.; Tucker, B. E.; Yuan, F.; Schmidt, B. P. ^[1]; Cenko, S. B.; Filippenko, A. V. ^[2]; Silverman, J. M. ^[3]; Contreras, C.; Hsiao, E. Y.; Phillips, M.; Morrell, N. ^[4]; Jha, S. W.; McCully, C. ^[5]; Anderson, J. P.; De Jaeger, T.; Forster, F. ^[6]; Benetti, S. ^[7]; others, and

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1. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia)
2. Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)
3. Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States)
4. Las Campanas Observatory, Carnegie Observatories, Casilla 601, La Serena (Chile)
5. Department of Physics and Astronomy, Rutgers, State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)
6. Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile)
7. INAF Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova (Italy)

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 {lambda}6355 line that can be cleanly decoupled from the lower velocity ''photospheric'' component. This Si II {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 {approx}12,000 km s{sup -1} until at least five weeks after maximum brightness. The Ca II infrared triplet exhibits similar evidence for both a photospheric component at v Almost-Equal-To 12,000 km s{sup -1} with narrow line width and long velocity plateau, as well as an HVF beginning at v Almost-Equal-To 31,000 km s{sup -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.

• OSTI ID: 22127164
• Journal Information: Astrophysical Journal, Vol. 770, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BRIGHTNESS
GALAXIES
LINE WIDTHS
SILICON
SPECTRA
SUPERNOVAE
TRIPLETS
VELOCITY