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Paper: A Spectroscopic Event Viewed from Different Directions
Volume: 332, The Fate of the Most Massive Stars
Page: 137
Authors: Stahl, O.; Weis, K.; Bomans, D.; Davidson, K.; Humphreys, R.M.; Gull, T.R.
Abstract: We present spectroscopic observations with high spectral resolution of the Homunculus nebula of η Car over the 2003.5 "spectroscopic event". The observed spectra represent the stellar spectrum emitted near the pole of the star and are much less contaminated with nebular emission lines than groundbased observations of the central object. The "event" is qualitatively similar near the pole to what is observed in direct spectra of the star (more equatoron), but shows interesting differences. A high-velocity absorption is present near the event, indicating that the event is not only a change in ionization and excitation structure. He IIλ4686 emission is observed for a brief period of time near the event and appears to precede similar emission at the center. The observations show that the spectroscopic event is less pronounced in Hα at the pole than at the equator of η Car.
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