2015ApJ...807...59H

We present extensive ultraviolet, optical, and near-infrared observations of the Type IIP supernova (SN IIP) 2013ej in the nearby spiral galaxy M74. The multicolor light curves, spanning from ∼8-185 days after explosion, show that it has a higher peak luminosity (i.e., M_V∼ -17.83 mag at maximum light), a faster post-peak decline, and a shorter plateau phase (i.e., ∼50 days) compared to the normal Type IIP SN 1999em. The mass of ⁵⁶Ni is estimated as 0.02±0.01 M_☉ from the radioactive tail of the bolometric light curve. The spectral evolution of SN 2013ej is similar to that of SN 2004et and SN 2007od, but shows a larger expansion velocity (i.e., v_Fe ii_∼ 4600 km/s at t ∼ 50 days) and broader line profiles. In the nebular phase, the emission of the Hα line displays a double-peak structure, perhaps due to the asymmetric distribution of ⁵⁶Ni produced in the explosion. With the constraints from the main observables such as bolometric light curve, expansion velocity, and photospheric temperature of SN 2013ej, we performed hydrodynamical simulations of the explosion parameters, yielding the total explosion energy as ∼0.7x 10⁵¹ erg, the radius of the progenitor as ∼600 R_☉, and the ejected mass as ∼10.6 M_☉. These results suggest that SN 2013ej likely arose from a red supergiant with a mass of 12-13 M_☉ immediately before the explosion.