Betelgeuse, the Prototypical Red Supergiant

TL;DR

This paper reviews recent observational and theoretical studies of Betelgeuse, focusing on its 2019-2020 dimming event, surface mass ejection, potential companion, and implications for understanding red supergiants.

Contribution

It synthesizes six years of observational data and theoretical models to explain Betelgeuse's recent behavior and explores the possibility of a companion object.

Findings

The 2019-2020 dimming was caused by a surface mass ejection.

Betelgeuse may have a companion object influencing its variability.

The star's behavior provides insights into supergiant star evolution.

Abstract

The behavior of the bright red supergiant, Betelgeuse, is described with results principally from the past 6 years. The review includes imaging, photometry, and spectroscopy to record the Great Dimming of 2019--2020. This event was followed by a slow ongoing recovery from the massive surface mass ejection after which the stellar characteristics changed. Theoretical simulations address the cause of this episodic mass ejection and the optical Dimming. Recent publications evaluating the perplexing 2100 day periodicity in the star's brightness and radial velocity provide evidence that Betelgeuse may harbor a companion object. Current attempts at direct detection of this companion are discussed. Betelgeuse provides a well-studied and meaningful example for supergiant stars in our Galaxy and others.