The lowest metallicity type II supernova from the highest mass red-supergiant progenitor
arXiv:1805.04434
Abstract
Red supergiants have been confirmed as the progenitor stars of the majority of hydrogen-rich type II supernovae. However, while such stars are observed with masses >25M, detections of >18M progenitors remain elusive. Red supergiants are also expected to form at all metallicities, but discoveries of explosions from low-metallicity progenitors are scarce. Here, we report observations of the type II supernova, SN 2015bs, for which we infer a progenitor metallicity of 0.1Z from comparison to photospheric-phase spectral models, and a Zero Age Main-Sequence mass of 17-25M through comparison to nebular-phase spectral models. SN 2015bs displays a normal 'plateau' light-curve morphology, and typical spectral properties, implying a red supergiant progenitor. This is the first example of such a high mass progenitor for a 'normal' type II supernova, suggesting a link between high mass red supergiant explosions and low-metallicity progenitors.
Accepted for publication in Nature Astronomy. Archive submission includes main text plus one table and three figures, together with Supplementary Information with an additional 12 figures and five tables