Structure and variability of H. cap alpha. emission in early-type supergiants

Journal Article · Thu Apr 01 04:00:00 EST 1982 · Astrophys. J., Suppl. Ser.; (United States)

DOI:https://doi.org/10.1086/190783· OSTI ID:5235132

Ebbets, D

Line profiles and equivalent widths are presented for H..cap alpha.. and H..beta.. in a sample of O and B supergiants. By making reference to model atmospheres and stellar wind theory, emission line luminosities are derived and shown to correlate with the rate of mass loss. Variability is observed to occur on a dynamical time scale of 1/sup d/--10/sup d/. The nature of the variations suggests that the velocity of outflowing material fluctuates with an amplitude of approx.100 km s/sup -1/ and that the fluctuations are not globally symmetric. No evidence for rapid variations with time scales shorter than 6 hr was found. Previously published H..cap alpha.. profiles indicate that for the most luminous stars changes in emission line luminosity by as much as a factor of 3 have occurred on time scales of years or longer. In other stars the profile has varied continuously, but changes in overall strength by more than a factor of a 2 are not indicated. Variations of the mass loss rates of 10% to 30% were inferred for all stars which were observed 3 or more times. In most stars the photospheric absorption lines remained unchanged, but in several cases the He I lambda6678 profile was asymmetric and varied with the same time scale as the H..cap alpha.. emission.

• Research Organization: McDonald Observatory, University of Texas at Austin, and Department of Astronomy, University of Wisconsin-Madison
• OSTI ID: 5235132
• Journal Information: Astrophys. J., Suppl. Ser.; (United States), Journal Name: Astrophys. J., Suppl. Ser.; (United States) Vol. 48:4; ISSN APJSA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BALMER LINES
GIANT STARS
LINE WIDTHS
LUMINOSITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
STARS
STELLAR ATMOSPHERES
STELLAR WINDS
SUPERGIANT STARS
VARIATIONS