SN 2015bp: adding to the growing population of transitional type Ia supernovae

Shubham Srivastav; G. C. Anupama; D. K. Sahu; C. D. Ravikumar

doi:10.1093/mnras/stw3263

paper

SN 2015bp: adding to the growing population of transitional type Ia supernovae

arXiv:1612.04735 · doi:10.1093/mnras/stw3263

Abstract

Photometric and spectroscopic observations of type Ia supernova 2015bp are presented, spanning $\sim - 6$ to $\sim + 141$ days since $B$ -band maximum. Also presented are unpublished HCT spectra of type Ia iPTF13ebh between $- 11$ to +34 days since $B$ -band maximum. SN 2015bp shows rapidly declining light curves with $Δ m_{15} (B) = 1.72 \pm 0.04$ . The $I$ -band light curve shows a clear secondary maximum and peaks before the $B$ -band maximum, placing SN 2015bp in the transitional category of SNe Ia. The spectral evolution of SN 2015bp resembles other transitional SNe Ia rather than 1991bg-like events. The C~{\sc ii} $λ 6580$ feature is detected in both SN 2015bp and iPTF13ebh, though it is present till the epoch of $B$ -band maximum in the case of SN 2015bp. The velocity gradients of Si~{\sc ii} $λ 6355$ place SN 2015bp and iPTF13ebh in the FAINT subclass, whereas pseudo-equivalent widths of Si~{\sc ii} features place them in the Cool (CL) subclass of SNe Ia. The bolometric light curve of SN 2015bp indicates that $\sim 0.2$ M $_{⊙}$ of $^{56}$ Ni was synthesized in the explosion, with a total ejected mass of $\sim 0.9$ M $_{⊙}$ , suggesting a sub-Chandrasekhar mass white dwarf progenitor.

arXiv comment16 pages, 16 figures, MNRAS accepted

SN 2015bp: adding to the growing population of transitional type Ia supernovae

Abstract

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