2014MNRAS.445.1932S

We present optical UBVRI photometry and medium resolution spectroscopy of the Type Ib supernova iPTF13bvn, spanning a phase of ∼ -13d to +71d with respect to B-band maximum. The post-maximum decline rates indicate a fast decline with Δm15(B) = 1.82. Correcting for a Galactic extinction E(B - V)MW = 0.045 and host galaxy extinction of E(B - V)host = 0.17, the absolute V-band magnitude peaks at MV = -17.23±0.20. The bolometric light curve indicates that ∼ 0.09 M_☉ of 56Ni was synthesized in the explosion. The earliest spectrum (-13d) shows the presence of Hei 5876Å feature at a velocity of ∼ 15 000 km/s, which falls rapidly by the time the SN approaches the epoch of B-band maximum. The photospheric velocity near maximum light, as indicated by the FeII 5169Å feature, is ∼ 9000 km/s. The estimate for the 56Ni mass, together with the estimates for the ejected mass (Mej) and kinetic energy of the explosion (Ek) indicate that iPTF13bvn is a low-luminosity Type Ib supernova, with a lower than average ejected mass and kinetic energy. Our results suggest that the progenitor of iPTF13bvn is inconsistent with a single Wolf-Rayet star.