Spectroscopic and photometric investigation of the A2 Ia-0 star HD 160529.
Abstract
Summary. A simultaneous photometric (uvby) and high dispersion (12 A/mm) spectroscopic investigation of the extreme galactic A-supergiant HD 160529 has been carried out. From large radial velocity variations, of an amplitude of 40 km/s, and from a variable splitting of the Ti II-, Fe ii- and Cr n-lines of a maximal separation of 42 km/s, the existence of very pronounced time- and depth-dependent non thermal photospheric velocity fields was inferred. The measured intensity variations of the absorption lines of about 20 % and the considerable photometric variations with an amplitude of 0.27 in y and of 0.18 in (u - v) are explained by the action of these velocity fields. It is suggested that such variable velocity fields likewise provide and explanation for correlated line intensity and radial velocity-variations. The mass flux, coupled with the velocity field, is supposed to produce a chromosphere in HD 160529 by mechanical energy dissipation. The detected emission features of H , H , and of the Fen-lines at 5991, 6432 and 6516 (these Fe n-lines are known to occur in nova like variables in emission), as well as the absorption line He 5876 are considered as chromospheric in origin. A variability of the H -emiSSiOn component, with changes from an inverse to a normal "P-Cygni" type profile, was found. The strong coupling of the line splitting and the intensity variations of the Fe il-emission lines was investigated. Key words: A-supergiant - photometric variations - spectral variations mass flux - chromosphere
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1974
- Bibcode:
- 1974A&A....36...87W
- Keywords:
-
- A Stars;
- Stellar Atmospheres;
- Stellar Spectrophotometry;
- Supergiant Stars;
- Variable Stars;
- Absorption Spectra;
- Abundance;
- Line Spectra;
- Magellanic Clouds;
- Radial Velocity;
- Velocity Distribution;
- Astrophysics