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The nearby Type Ibn supernova 2015G: signatures of asymmetry and progenitor constraints

Article

Overview

Abstract

  • We present the results of an extensive observational campaign on the nearby Type Ibn SN 2015G, including data from radio through ultraviolet wavelengths. SN 2015G was asymmetric, showing late-time nebular lines redshifted by ~1000 km s-1. It shared many features with the prototypical SN Ibn 2006jc, including extremely strong He I emission lines and a late-time blue pseudo-continuum. The young SN 2015G showed narrow P-Cygni profiles of He I, but never in its evolution did it show any signature of hydrogen - arguing for a dense, ionized and hydrogen-free circumstellar medium moving outward with a velocity of ~1000 km s-1 and created by relatively recent mass-loss from the progenitor star. Ultraviolet through infrared observations show that the fading SN 2015G (which was probably discovered some 20 d post-peak) had a spectral energy distribution that was well described by a simple, single-component blackbody. Archival HST images provide upper limits on the luminosity of SN 2015G's progenitor, while non-detections of any luminous radio afterglow and optical non-detections of outbursts over the past two decades provide constraints upon its mass-loss history.

Published In

Publication Date

  • 2017

Identity

Digital Object Identifier (doi)

Additional Document Info

Start Page

  • 4381

End Page

  • 4397

Volume

  • 471