A Change in the Physical State of η Carinae?
Weis, K.; Stahl, O.; Davidson, K.; Gull, T. R.; Humphreys, R. M.; Hillier, D. J.; Martin, J.; Hamann, F.; Damineli, A.; Ishibashi, K.; Corcoran, M.
United States, Germany, Brazil
Abstract
During η Car's spectroscopic event in mid-2003, the stellar wind's bright Hα and Hβ emission lines temporarily had a distinctive shape unlike that reported on any previous occasion and particularly unlike the 1997-1998 event. Evidently the structure of the wind changed between 1997 and 2003. Combining this with other evidence, we suspect that the star may now be passing through a rapid stage in its recovery from the Great Eruption seen 160 years ago. In any case, the data indicate that successive spectroscopic events differ, and the hydrogen line profiles are quantitative clues to the abnormal structure of the wind during a spectroscopic event.
This research is part of the Hubble Space Telescope Treasury Project for Eta Carinae, supported by grants GO-9420 and GO-9973 from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.