We present mid-infrared observations with the Spitzer Space Telescope of the nearby type II-P supernova, SN 2004dj, at epochs of 89 to 129 days. We have obtained the first mid-IR spectra of any supernova apart from SN 1987A. A prominent [NiII] 6.64 micron line is observed, from which we deduce that the mass of stable nickel must be at least 2.2e10(-4) Msun. We also observe the red wing of the CO-fundamental band. We relate our findings to possible progenitors and favour an evolved star, most likely a red supergiant, with a probable initial mass between ~10 and 15 Msun.
@article{arxiv.astro-ph/0506407,
title = {Early-time Spitzer observations of the type II-Plateau supernova, 2004dj},
author = {Rubina Kotak and Peter Meikle and Schuyler van Dyk and Peter Hoeflich and Seppo Mattila},
journal= {arXiv preprint arXiv:astro-ph/0506407},
year = {2009}
}