Proceedings of the International Astronomical Union

Contributed Papers

JD13 – Eta Carinae in the Context of the Most Massive Stars

Theodore R. Gulla1 and Augusto Daminelia2

a1 Laboratory for Extraterrestial Planets and Stellar Astrophysics, Code 667, NASA/GSFC, Greenbelt, MD, 20771, USA, email:

a2 IAGSP, Universidade de Sao Paulo, Rua do Matao 1226, Sao Paulo, 05508-900, Brazil, email:

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, η 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 γ-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, η Car behaved both predictably and unpredictably during this most recent periastron, spurring timely discussions.