Doppler imaging of stellar surface structure XIV. The double-lined pre-main-sequence binary V 824 Arae = HD 1.55555

Citation
Kg. Strassmeier et Jb. Rice, Doppler imaging of stellar surface structure XIV. The double-lined pre-main-sequence binary V 824 Arae = HD 1.55555, ASTRON ASTR, 360(3), 2000, pp. 1019-1030
Citations number
45
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
00046361 → ACNP
Volume
360
Issue
3
Year of publication
2000
Pages
1019 - 1030
Database
ISI
SICI code
0004-6361(200008)360:3<1019:DIOSSS>2.0.ZU;2-R
Abstract
Photospheric Doppler images for both stellar components of the double-lined pre-main-sequence binary V 824 Ara reveal surface temperature inhomogeneit ies of up to 1800 K on both stars. The spot geometry on the hotter primary is dominated by an elongated, tilted, equatorial feature but our maps from two spectral regions consistently also show a polar spot cooler by 1700 K. The secondary star has spots mainly at low and very high latitudes but not a full-sized polar cap. A flux-tube simulation with appropriate stellar mod els for V 824 Ara suggests that any polar or high-latitude spot must have f ormed after flux-tube emergence. Generally, the low-latitude spots on both stellar components appear to be mostly concentrated on the hemispheres turn ed away from each other while the asymmetry of the polar spot on the primar y points in the direction of the orbital motion. We present new radial velocities and use them to re-evaluate the orbital el ements and to derive absolute parameters for both stellar components. The a bsolute brightness and mass of the two stars suggest that they are very clo se to the main sequence - but not yet on the ZAMS - if an inclination of th e orbital plane (and rotational axes) of 52 degrees is adopted as suggested by the Doppler imaging. Since both stars are active, we solve for the incl inations of both stellar components separately and find that the values agr ee to within their uncertainties.