Wolf-Rayet stars -- what we know and what we don't

TL;DR

This paper reviews the current understanding of Wolf-Rayet stars, highlighting recent progress in observational and theoretical studies, and discusses remaining open questions in their evolution and characteristics.

Contribution

It provides a comprehensive overview of the historical development and current state of knowledge on Wolf-Rayet stars, emphasizing areas still lacking understanding.

Findings

Stellar evolution predictions align with observed WR star parameters.

Population synthesis models match the observed number of WR stars.

Key questions about WR star formation and evolution remain open.

Abstract

Today, we have a sufficiently complete picture of what the Wolf--Rayet (WR) stars are. Predictions of stellar evolution theory are in a good agreement with their parameters, estimated from observational data using stellar atmospheres codes; predictions of population synthesis also agree well with number of known WR stars. This article provides an overview of the main historical milestones in the studies of WR stars, showing how we came to this understanding, and what questions are still unanswered.