# Type Ibn Supernovae May not all Come from Massive Stars

## TL;DR

This study investigates the origins of Type Ibn supernovae, particularly challenging the idea that they all come from massive stars by analyzing the environment of PS1-12sk with deep ultraviolet imaging.

## Contribution

It provides new constraints on star formation at the supernova site, questioning the assumption that all Type Ibn supernovae originate from massive stars.

## Key findings

- No ultraviolet emission detected near PS1-12sk, indicating very low star formation.
- Deepened the limit on star formation rate by an order of magnitude.
- Discussed alternative progenitor scenarios beyond massive Wolf-Rayet stars.

## Abstract

Because core-collapse supernovae are the explosions of massive stars, which have relatively short lifetimes, they occur almost exclusively in galaxies with active star formation. On the other hand, the Type Ibn supernova PS1-12sk exploded in an environment much more typical of thermonuclear (Type Ia) supernovae: on the outskirts of the brightest elliptical galaxy in a galaxy cluster. The lack of any obvious star formation at that location presented a challenge to models of Type Ibn supernovae as the explosions of very massive Wolf-Rayet stars. Here we present a supplementary search for star formation at the site of PS1-12sk, now that the supernova has faded, via deep ultraviolet imaging of the host cluster with the Hubble Space Telescope. We do not detect any ultraviolet emission within 1 kpc of the supernova location, which allows us deepen the limit on star formation rate by an order of magnitude compared to the original study on this event. In light of this new limit, we discuss whether the progenitors of Type Ibn supernovae can be massive stars and what reasonable alternatives have been proposed.