SN 2012fr: Ultraviolet, Optical, and Near-infrared Light Curves of a Type Ia Supernova Observed within a Day of Explosion

• Published in: The Astrophysical journal 2018-05, Vol.859 (1), p.24
• Main Authors: Contreras, Carlos, Phillips, M. M., Burns, Christopher R., Piro, Anthony L., Shappee, B. J., Stritzinger, Maximilian D., Baltay, C., Brown, Peter J., Conseil, Emmanuel, Klotz, Alain, Nugent, Peter E., Turpin, Damien, Parker, Stu, Rabinowitz, D., Hsiao, Eric Y., Morrell, Nidia, Campillay, Abdo, Castellón, Sergio, Corco, Carlos, González, Consuelo, Krisciunas, Kevin, Serón, Jacqueline, Tucker, Brad E., Walker, E. S., Baron, E., Cain, C., Childress, Michael J., Folatelli, Gastón, Freedman, Wendy L., Hamuy, Mario, Hoeflich, P., Persson, S. E., Scalzo, Richard, Schmidt, Brian, Suntzeff, Nicholas B.
• Format: Article
• Language: English
• Subjects: ASTRONOMY AND ASTROPHYSICS; Astrophysics; Bolometers; Cosmic dust; Distance measurement; Ejecta; Evolution; Explosions; Galaxies; Infrared radiation; Light curve; Luminosity; Photosphere; SN 2012fr; Supernova; Supernovae; Velocity
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.3847/1538-4357/aabaf8

We present detailed ultraviolet, optical, and near-infrared light curves of the Type Ia supernova (SN) 2012fr, which exploded in the Fornax cluster member NGC 1365. These precise high-cadence light curves provide a dense coverage of the flux evolution from −12 to +140 days with respect to the epoch of B -band maximum ( t B max ). Supplementary imaging at the earliest epochs reveals an initial slow and nearly linear rise in luminosity with a duration of ∼2.5 days, followed by a faster rising phase that is well reproduced by an explosion model with a moderate amount of 56 Ni mixing in the ejecta. From our analysis of the light curves, we conclude that: (i) the explosion occurred  1800 Å) luminosity was 16.5 ± 0.6 days, (iii) the supernova suffered little or no host-galaxy dust reddening, (iv) the peak luminosity in both the optical and near-infrared was consistent with the bright end of normal Type Ia diversity, and (v) 0.60 ± 0.15 M ⊙ of 56 Ni was synthesized in the explosion. Despite its normal luminosity, SN 2012fr displayed unusually prevalent high-velocity Ca ii and Si ii absorption features, and a nearly constant photospheric velocity of the Si ii λ 6355 line at ∼12,000 km s − 1 that began ∼5 days before t B max . We also highlight some of the other peculiarities in the early phase photometry and the spectral evolution. SN 2012fr also adds to a growing number of Type Ia supernovae that are hosted by galaxies with direct Cepheid distance measurements.