Optical and near-infrared coverage of SN 2004et: physical parameters and comparison with other Type IIP supernovae

Abstract

We present new optical and near infrared (NIR) photometry and spectroscopy of\nthe type IIP supernova, SN 2004et. In combination with already published data,\nthis provides one of the most complete studies of optical and NIR data for any\ntype IIP SN from just after explosion to +500 days. The contribution of the NIR\nflux to the bolometric light curve is estimated to increase from 15% at\nexplosion to around 50% at the end of the plateau and then declines to 40% at\n300 days. SN 2004et is one of the most luminous IIP SNe which has been well\nstudied, and with a luminosity of log L = 42.3 erg/s, it is 2 times brighter\nthan SN 1999em. We provide parametrised bolometric corrections as a function of\ntime for SN 2004et and three other IIP SNe that have extensive optical and NIR\ndata, which can be used as templates for future events. We compare the physical\nparameters of SN 2004et with those of other IIP SNe and find kinetic energies\nspanning the range of 10^50-10^51 ergs. We compare the ejected masses\ncalculated from hydrodynamic models with the progenitor masses and limits\nderived from prediscovery images. Some of the ejected mass estimates are\nsignificantly higher than the progenitor mass estimates, with SN 2004et showing\nperhaps the most serious mass discrepancy. With current models, it appears\ndifficult to reconcile 100 day plateau lengths and high expansion velocities\nwith the low ejected masses of 5-6 Msun implied from 7-8 Msun progenitors. The\nnebular phase is studied using very late time HST photometry, along with\noptical and NIR spectroscopy. The light curve shows a clear flattening at 600\ndays in the optical and the NIR, which is likely due to the ejecta impacting on\nthe CSM. We further show that the [Oi] 6300,6364 Angstrom line strengths of\nfour type IIP SNe imply ejected oxygen masses of 0.5-1.5 Msun.\n