Eta Carinae in the Context of the Most Massive Stars

TL;DR

Eta Carinae is a complex, massive binary star system with recent multi-wavelength observations revealing both predictable and unpredictable behaviors, offering insights into the evolution and fate of the most massive stars.

Contribution

This paper reviews recent observational campaigns and models of Eta Carinae, highlighting new data and comparisons with other massive binaries to understand massive star evolution.

Findings

Eta Carinae is a 5.54-year period massive binary system.

Recent observations captured both predictable and unpredictable behaviors during periastron.

Comparative analysis with other massive binaries informs theories of stellar evolution.

Abstract

Eta Car, with its historical outbursts, visible ejecta and massive, variable winds, continues to challenge both observers and modelers. In just the past five years over 100 papers have been published on this fascinating object. We now know it to be a massive binary system with a 5.54-year period. In January 2009, Eta Car underwent one of its periodic low-states, associated with periastron passage of the two massive stars. This event was monitored by an intensive multi-wavelength campaign ranging from gamma-rays to radio. A large amount of data was collected to test a number of evolving models including 3-D models of the massive interacting winds. August 2009 was an excellent time for observers and theorists to come together and review the accumulated studies, as have occurred in four meetings since 1998 devoted to Eta Car. Indeed, Eta Car behaved both predictably and unpredictably during this most recent periastron, spurring timely discussions. Coincidently, WR140 also passed through periastron in early 2009. It, too, is a intensively studied massive interacting binary. Comparison of its properties, as well as the properties of other massive stars, with those of Eta Car is very instructive. These well-known examples of evolved massive binary systems provide many clues as to the fate of the most massive stars. What are the effects of the interacting winds, of individual stellar rotation, and of the circumstellar material on what we see as hypernovae/supernovae? We hope to learn.