Eta Car: The Good, the Bad and the Ugly of Nebular and Stellar Confusion

Observations in the far‐UV provide a unique opportunity to investigate the very massive star η Car and its hot binary companion, η Car B. η Car was observed with FUSE over a large portion of the 5.54 year spectroscopic period before and after the 2003.5 minimum. The observed spectrum is defined by strong stellar wind signatures, primarily from η Car A, complicated by the strong absorptions of the ejecta surrounding η Car plus interstellar absorption. The Homunculus and Little Homunculus are massive bipolar ejecta historically associable with LBV outbursts in the 1840s and the 1890s and are linked to absorptions at −513 and −146 km s−1, respectively. The FUSE spectra are confused by the extended nebulosity and thermal drifting of the FUSE co‐pointed instruments. Interpretation is further complicated by two B‐stars sufficiently close to η Car to be included most of the time in the large FUSE aperture. Followup observations partially succeeded in obtaining spectra of at least one of these B‐stars through the...