The Eta Carinae 2009 Campaign
CRESST/NASA-GSFC, Greenbelt MD USA, and Universities Space Research Association, Columbia, MD USA
Abstract
In January 2009, the enigmatic, extremely massive and luminous star Eta Car went through one of its periodic “minimum” states in which the excitation of its circumstellar nebula, along with the 2–10 keV emission from the star, collapses for a brief period. Current understanding associates this minimum state with the occurrence of periastron passage of a massive, unseen hot companion star around the much more luminous, much more massive Eta Car. These events offer a direct probe of the mass loss from Eta Car and the system as a whole, with circumstantial evidence tying these events to the spectacular “Great” and “Lesser” eruptions of the 19th century. As such these events have attracted the interest of a broad community of stellar and nebular astrophysicists. I report here on the results obtained during a nearly pan-chromatic campaign of observations of the January 2009 minimum, with some emphasis on the unique aspects of this particular minimum.