Optical observations of line profile variability in the WN5 star HD 50896
Autor: | Linda J. Smith, Allan J. Willis |
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Rok vydání: | 1994 |
Předmět: | |
Zdroj: | Astrophysics and Space Science. 221:189-196 |
ISSN: | 1572-946X 0004-640X |
Popis: | The WN5 star HD 50896 is a well known variable star but the cause of the variations is uncertain. As part of an extensive observing campaign on HD 50896, 68 spectra were obtained with the AAT and UCL echelle spectrograph over three nights in January 1991. The variations seen in the emission line profiles of He II λ4686, He II λ4860, N V λ4945 and N V λ4603, λ4620, sampling different regions of the wind, are described. Gross night-to-night changes are seen in the tops of all the emission lines, with the pattern of variability being different for each line, as a consequence of the different line formation regions. The edges of the emission line profiles are seen to shift but not in a systematic way, as expected for binary motion. In terms of hourly variations which monitor the propagation of instabilities in the wind, distinct ‘blobs’ are seen moving outwards through the emission line profiles of the He II lines but are absent in N V λ4945. This appears to indicate that, at least for the epoch of these observations, the instabilities develop farther out in the wind than the N V formation region and may well rule out photospheric-induced wind instabilities. |
Databáze: | OpenAIRE |
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