The structure and variability of H-alpha emission in early-type supergiants

Abstract

view Abstract Citations (110) References (60) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The structure and variability of H alf emission in early-type supergiants. Ebbets, D. Abstract Line profiles and equivalent widths are presented for H-alpha and H-beta in a sample of O and B supergiants to clarify the nature of variability at H-alpha, especially with respect to the time scale. Emission line luminosities are derived and are shown to correlate with the rate of mass loss. The presence of emission wings visible to over half the terminal velocity implies that density drops smoothly with increasing velocity, with a gradual rather than abrupt acceleration. Variability occurs on a dynamical time scale of 1-10 d, and the nature of the variation suggests the velocity of outflowing material fluctuates with an amplitude of about 100 km/s. No correlation appears to exist between the velocity shifts of the blue and red edges, which argues against symmetry and suggests that localized fluctuations in the velocity law are common. Publication: The Astrophysical Journal Supplement Series Pub Date: April 1982 DOI: 10.1086/190783 Bibcode: 1982ApJS...48..399E Keywords: Early Stars; H Alpha Line; H Beta Line; Periodic Variations; Spectral Line Width; Stellar Mass Ejection; Supergiant Stars; Absorption Spectra; B Stars; O Stars; Stellar Luminosity; Stellar Winds; Velocity Distribution; Astrophysics full text sources ADS | data products SIMBAD (25)