Searching for Wolf-Rayet Stars in M101

TL;DR

This study demonstrates that narrow-band optical imaging significantly improves the detection efficiency of Wolf-Rayet stars in M101, impacting the interpretation of their role as supernova progenitors.

Contribution

It provides the first comprehensive comparison of narrow-band versus broad-band detection methods for Wolf-Rayet stars in M101, highlighting the importance of narrow-band imaging.

Findings

42% of WR stars detected in broad-band imaging

Detection efficiency increases to ~85% in central regions

Non-detection in broad-band does not exclude WR progenitors

Abstract

Wolf-Rayet (WR) stars are the evolved descendants of massive O-type stars and are considered to be progenitor candidates for Type Ib/c core-collapse supernovae (SNe). Recent results of our HST/WFC3 survey of Wolf-Rayet stars in M101 are summarised based on the detection efficiency of narrow-band optical imaging compared to broad-band methods. Weshow that on average of 42% WR stars, increasing to ~85% in central regions, are only detected in the narrow-band imaging. Hence, the non-detection of a WR star at the location of ~10 Type Ib/c SNe in broad-band imaging is no longer strong evidence for a non-WR progenitor channel.