Spectroscopic studies of O-type stars. VI - The earliest types: O3-O5.5

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view Abstract Citations (148) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectroscopic studies of O-type stars. VI. The earliest types: O3 - O5.5. Conti, P. S. ; Frost, S. A. Abstract We present equivalent widths and selected line profiles obtained from multiple coude' spectrograms of 20 early 0 and Of stars. In the hottest stars, the O3 types, the neutral helium lines are absent, and in the other stars it is essentially the strength of He I A4471 that determines the spectral type. In these early 0-type stars the ionized helium lines are relatively insensitive to temperature and slightly weaker than predicted by the non-LTE models of Auer and Mihalas. The presence of strong emission at Ha and/or He ii A4686 in seven of these stars suggests appreciable mass loss via a stellar wind. Neither of these emission lines nor N iii AA4634, 4640, 4641 exhibited noteworthy variations during the period of observation. The rates of mass loss, as deduced from the formalism of Klein and Castor, are of order l0- yr . These rates are sufficiently large, if continued throughout the hydrogen burning lifetime of the star, to carry away a significant fraction of the mass of the star. Subject headings: line profiles - stars: early-type - stars: mass loss - stars: Of-type Publication: The Astrophysical Journal Pub Date: March 1977 DOI: 10.1086/155098 Bibcode: 1977ApJ...212..728C Keywords: Early Stars; Emission Spectra; Line Spectra; O Stars; Stellar Spectra; H Alpha Line; Hertzsprung-Russell Diagram; Mass Transfer; Spectral Line Width; Stellar Mass; Astronomy full text sources ADS | data products SIMBAD (19) Related Materials (8) Part 1: 1971ApJ...170..325C Part 2: 1973ApJ...179..161C Part 3: 1973ApJ...179..181C Part 4: 1974ApJ...187..539C Part 5: 1974ApJ...193..113C Part 7: 1977ApJ...213..438C Part 8: 1977ApJ...214..759C Part 9: 1980ApJ...242.1063G