PHOTOSPHERIC VARIATIONS OF THE SUPERGIANT {gamma} Cyg
- Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7 (Canada)
New high-resolution spectroscopic observations of the supergiant {gamma} Cyg (F8 Iab) taken between 2000 and 2008 consistently show strongly reversed-C-shaped bisectors for all unblended spectral lines. Small-amplitude variations in radial velocity and line shapes occur in an irregular manner with time scales {approx}100 days and longer. The radial velocities occasionally show changes as large as 2 km s{sup -1}, but much smaller changes are going on continuously. Differential line bisectors show shape changes and Doppler displacement characteristic of radial expansion and contraction. These might arise from non-periodic radial pulsation-like motions or from the appearance of giant convection cells that occupy most of the visible hemisphere of the star. Line-depth ratios are correlated with the line shifts on a seasonal basis and indicate temperature changes ranging up to {approx}15 K, with larger temperature occurring during times of most rapid contraction.
- OSTI ID:
- 21443203
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 140, Issue 5; Other Information: DOI: 10.1088/0004-6256/140/5/1329; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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