Supernova 2012ec: Identification of the progenitor and early monitoring with PESSTO

TL;DR

This paper identifies the progenitor of supernova 2012ec using archival images, and presents early photometric and spectroscopic observations that classify it as a Type IIP supernova with a progenitor mass of 14-22 solar masses.

Contribution

First identification of a supernova progenitor followed by early monitoring with PESSTO, providing detailed constraints on progenitor properties and supernova evolution.

Findings

Progenitor identified in archival HST images.

SN 2012ec classified as Type IIP with a plateau light curve.

Progenitor mass estimated at 14-22 solar masses.

Abstract

We present the identification of the progenitor of the Type IIP SN 2012ec in archival pre-explosion HST WFPC2 and ACS/WFC F814W images. The properties of the progenitor are further constrained by non-detections in pre-explosion WFPC2 F450W and F606W images. We report a series of early photometric and spectroscopic observations of SN 2012ec. The r'-band light curve shows a plateau with M(r')=-17.0. The early spectrum is similar to the Type IIP SN 1999em, with the expansion velocity measured at Halpha absorption minimum of -11,700 km/s (at 1 day post-discovery). The photometric and spectroscopic evolution of SN 2012ec shows it to be a Type IIP SN, discovered only a few days post-explosion (<6d). We derive a luminosity for the progenitor, in comparison with MARCS model SEDs, of log L/Lsun = 5.15+/-0.19, from which we infer an initial mass range of 14-22Msun. This is the first SN with an identified progenitor to be followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO).