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K. Ishibashi (CSR/MIT)
Eta Carinae is suspected to have a massive (~ 30MSun) binary companion with an orbital period of 5.5 years. However, spectroscopic studies with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) could not detect any strong signature for Doppler motion in optical emission lines. Instead the HST/STIS data show that line profile of high-excitation species (e.g., He I) varies. This profile variation may be misinterpreted as the variation of radial velocity in the past. But the finding refutes a specific type -- not all -- of binary hypothesis published in journals. Furthermore, it is plausible that the profile variation may indicate dynamical changes in Eta Carinae's stellar wind influenced by the presence of a fast, tenuous companion star's wind.
High-resolution optical and X-ray spectroscopic data, obtained with the HST/STIS and Chandra X-ray Observatory/HETG, will be analyzed to show whether the variation in line profile can be related to any binary phenomenon.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.