On the nature of the circumstellar medium of the remarkable Type Ia/IIn supernova SN 2002ic

ABSTRACT

We present results from the first high-resolution, high signal-to-noise ratio spectrum of SN 2002ic. The resolved Hα line has a P Cygni-type profile, clearly demonstrating the presence of a dense, slow-moving  (∼100 km s⁻¹)  outflow. We have additionally found a huge near-infrared excess, hitherto unseen in Type Ia supernovae. We argue that this is due to an infrared light-echo arising from the pre-existing dusty circumstellar medium. We deduce a circumstellar medium mass probably exceeding  0.3 M_⊙  produced by a mass-loss rate greater than several times  10⁻⁴ M_⊙ yr⁻¹ . For the progenitor, we favour a single-degenerate system where the companion is a post-asymptotic giant branch star. As a by-product of our optical data, we are able to provide a firm identification of the host galaxy of SN 2002ic.