Spectrum variability of the A-type supergiant star HD 223960

Citation
Wj. Fischer et Nd. Morrison, Spectrum variability of the A-type supergiant star HD 223960, PUB AST S P, 113(785), 2001, pp. 821-828
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC
ISSN journal
0004-6280 → ACNP
Volume
113
Issue
785
Year of publication
2001
Pages
821 - 828
Database
ISI
SICI code
0004-6280(200107)113:785<821:SVOTAS>2.0.ZU;2-F
Abstract
HD 223960, an A0 Ia-type supergiant in the Cas OB5 association, is unusual among Galactic supergiants of its class in having an H alpha profile with d ouble-peaked emission entirely above the continuum. We analyzed 12 high-res olution echelle spectra obtained in 1993-1995 and in 1999 with the 1 m tele scope of Ritter Observatory. The radial velocities of photospheric Si, C, H e, Ne, and S lines were found to be constant to within +/-2 km s(-1), but t he data suggest variability in the equivalent widths of Si II lambda lambda 6347, 6371 and several other photospheric lines. The radial velocities and equivalent widths and, especially, the ratio V/R of the H alpha components vary. The present data do not indicate a binary explanation for the double -peaked emission feature. Alternative explanations are considered, but none is completely satisfactory. The available evidence is consistent with the star having a weak, fast wind.