Research in Astronomy and Astrophysics Optical observations of the broad-lined type Ic supernova SN 2012ap ∗

Abstract The optical observations of the type Ic supernova (SN Ic) SN 2012ap in NGC 1729 are presented. A comparison with other SNe Ic indicates that SN 2012ap is highly reddened (with E(B − V)host∼0.8 mag) and may represent one of the most luminous SNe Ic ever observed, with an absolute V-band peak magnitude of ∼ −19.3±0.5 mag after extinction correction. The near-maximum-light spectrum shows wide spectral features that are typical of broad-lined SNe Ic. One interesting feature in the spectrum is the appearance of some narrow absorption features that can be at-tributed to the diffuse interstellar bands, consistent with the large reddening inferred from the photometric method. Based on the light curves and the spectral data, we esti-mate that SN 2012ap produced a 56Ni mass of ∼ 0.3 ± 0.1M ¯ in the explosion, with an ejecta mass of 2.4+0.7−0.7M ¯ and a kinetic energy of EK = 1.1 +0.4 −0.4 × 1052 erg. The properties of its progenitor are also briefly discussed. Key words: supernovae: general — supernovae: individual: SN 2012a