Detection of circumstellar material in a normal Type Ia Supernova

TL;DR

This paper reports the detection of circumstellar material around a normal Type Ia supernova, providing evidence for the progenitor system involving a white dwarf accreting from a red-giant companion.

Contribution

First detection of circumstellar material in a normal Type Ia supernova, supporting the red-giant companion progenitor model.

Findings

Circumstellar material was detected around the supernova.

The properties of the material suggest it was ejected from the progenitor system.

Results favor a white dwarf accreting from a red-giant star.

Abstract

Type Ia supernovae are thought to be thermonuclear explosions of accreting white dwarfs that reach a critical mass limit. Despite their importance as cosmological distance indicators, the nature of their progenitors has remained controversial. Here we report the detection of circumstellar material in a normal Type Ia supernova. The expansion velocities, densities and dimensions of the circumstellar envelope indicate that this material was ejected from the progenitor system. The relatively low expansion velocities appear to favor a progenitor system where a white dwarf accretes material from a companion star which is in the red-giant phase at the time of explosion.