Evidence for a supersonic turbulent velocity gradient in the outer photosphere of the supergiant alpha Cygni (A2Ia)

The balloon-borne UV Stellar Spectrometer's high resolution, near-UV spectra of the supergiant Alpha Cyg are subjected to analysis in order to determine the average microturbulent line-of-sight velocity component. A value of 15.0 + or - 0.5 km/sec is obtained, which is close to the 13.7 km/sec...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 1984-12, Vol.141 (2, De), p.304-308
Main Authors: De Jager, C., Mulder, P. S., Kondo, Y.
Format: Article
Language:English
Subjects:
Astronomy
Astrophysics
Earth, ocean, space
Exact sciences and technology
Normal stars (by class): general or individual
Stars
Supergiant stars
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Summary:The balloon-borne UV Stellar Spectrometer's high resolution, near-UV spectra of the supergiant Alpha Cyg are subjected to analysis in order to determine the average microturbulent line-of-sight velocity component. A value of 15.0 + or - 0.5 km/sec is obtained, which is close to the 13.7 km/sec local sound velocity, and is consistent with the view that shock waves are the dominant structure in the outer photosphere of Deneb, so that shock wave dissipation determines the thermal structure of the photosphere.
ISSN:0004-6361
1432-0746