Eruptive Outflow Phases of Massive Stars

TL;DR

This paper reviews recent advances in understanding the diverse eruptive behaviors of massive stars, especially luminous blue variables, highlighting their significance in stellar evolution and the current gaps in physical mechanism explanations.

Contribution

It provides a comprehensive overview of observed eruption diversity in massive stars and discusses implications for stellar evolution and the physical mechanisms behind eruptions.

Findings

Eruptions show wide luminosity and speed ranges.

Multiple eruptions observed in some LBVs.

Implications for mass loss and stellar evolution.

Abstract

I review recent progress on understanding eruptions of unstable massive stars, with particular attention to the diversity of observed behavior in extragalatic optical transient sources that are generally associated with giant eruptions of luminous blue variables (LBVs). These eruptions are thought to represent key mass loss episodes in the lives of massive stars. I discuss the possibility of dormant LBVs and implications for the duration of the greater LBV phase and its role in stellar evolution. These eruptive variables show a wide range of peak luminosity, decay time, expansion speeds, and progenitor luminosity, and in some cases they have been observed to suffer multiple eruptions. This broadens our view of massive star eruptions compared to prototypical sources like Eta Carinae, and provides important clues for the nature of the outbursts. I also review and discuss some implications about the possible physical mechanisms involved, although the cause of the eruptions is not yet understood.