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Description
Extensive optical and UltraViolet (UV) observations of the type Ia supernova (SN Ia) 2012fr are presented in this paper. It has a relatively high luminosity, with an absolute B-band peak magnitude of about -19.5mag and a smaller post-maximum decline rate than normal SNe Ia (e.g., {Delta}m_15_(B)=0.85+/-0.05mag). Based on the UV and optical light curves, we derived that a ^56^Ni mass of about 0.88M_{sun}_ was synthesized in the explosion. The earlier spectra are characterized by noticeable high-velocity features of Si II {lambda}6355 and Ca II with velocities in the range of ~22000-25000km/s. At around the maximum light, these spectral features are dominated by the photospheric components which are noticeably narrower than normal SNe Ia. The post-maximum velocity of the photosphere remains almost constant at ~12000km/s for about one month, reminiscent of the behavior of some luminous SNe Ia like SN 1991T. We propose that SN 2012fr may represent a subset of the SN 1991T-like SNe Ia viewed in a direction with a clumpy or shell-like structure of ejecta, in terms of a significant level of polarization reported in Maund et al. (2013MNRAS.433L..20M).
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