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BAA Journal 2016 December

Supernova 2012fr and the distance to NGC 1365

Journal issue: 2016 December
Pages: 364–368

BVRI and unfiltered MicroObservatory CCD observations of SN 2012fr covering the first 100 days following its discovery are reported. The time of first light following the explosion of the SN progenitor is estimated to have been around 2012 October 24.6 (JD 2456225.1), giving a rise time to maximum light of ~19.27 days in the unfiltered passband. Lightcurves in the BVRI passbands, and the derived parameters for the SN, are similar to those observed by Zhang et al. and are consistent with those of typical ‘normal’ Type Ia SNe, including the presence of secondary maxima in the R and I bands approximately 25 days after B-band maximum brightness. The peak absolute magnitudes of the SN range from -19.28 (±0.19) to -19.51 (±0.17) depending on the passband, and give a mean distance modulus to the host galaxy, NGC 1365, of 31.48 ±0.19 (equivalent to ~19.5Mpc).  At ~0.7 M¤, the mass of 56Ni synthesized by the SN is consistent with the thermonuclear explosion of a carbon-oxygen white dwarf accreting mass from a companion star in a binary system, although the nature of the companion is undetermined. (continued)

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