Massive stars exploding in a He-rich circumstellar medium. II. The transitional case of SN 2005la

TL;DR

SN 2005la is a peculiar supernova with hybrid features, showing fluctuating luminosity and strong narrow hydrogen and helium lines, likely from circumstellar material, indicating a Wolf-Rayet progenitor with recent mass ejections.

Contribution

This study provides detailed photometric and spectroscopic analysis of SN 2005la, highlighting its hybrid properties and proposing a Wolf-Rayet star progenitor with recent mass ejections.

Findings

Spectral lines show increasing velocity, indicating circumstellar acceleration.

SN 2005la exhibits features of both Type IIn and Type Ibn supernovae.

Progenitor was a young Wolf-Rayet star with recent mass ejection episodes.

Abstract

We present photometric and spectroscopic data of the peculiar SN 2005la, an object which shows an optical light curve with some luminosity fluctuations and spectra with comparably strong narrow hydrogen and helium lines, probably of circumstellar nature. The increasing full-width-half-maximum velocity of these lines is indicative of an acceleration of the circumstellar material. SN 2005la exhibits hybrid properties, sharing some similarities with both type IIn supernovae and 2006jc-like (type Ibn) events. We propose that the progenitor of SN 2005la was a very young Wolf-Rayet (WN-type) star which experimented mass ejection episodes shortly before core collapse.