A study of the chromospherically active binaries UX Fornacis and AG Doradus

Citation
A. Washuettl et Kg. Strassmeier, A study of the chromospherically active binaries UX Fornacis and AG Doradus, ASTRON ASTR, 370(1), 2001, pp. 218-229
Citations number
57
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
0004-6361 → ACNP
Volume
370
Issue
1
Year of publication
2001
Pages
218 - 229
Database
ISI
SICI code
0004-6361(200104)370:1<218:ASOTCA>2.0.ZU;2-2
Abstract
This paper presents a time-series spectrum analysis of the two chromospheri cally active binary stars;, UX Fornacis and AG Doradus. To investigate the rotational behaviour, in combination with activity in the H alpha line, we obtained almost 40 high-resolution, high-SIN spectra for each system. Both binaries, UX For and AG Dor, show H alpha Of the primary star in absorption but filled in by chromospheric emission while the H alpha line of the seco ndaries appear in pure emission. Line variations are seen and are approxima tely 5-sigma detections but are not linked to the orbital nor the rotationa l periods and seem to be erratic. We obtained new orbital elements for both systems and used them in combination with Hipparcos parallaxes and our H a lpha -spectrum synthesis to determine absolute parameters. We present the f irst Doppler image of the AG Dor primary using line-profile variations of t he FeI lambda 6546 line. The image reveals a cool polar feature and three e quatorial spots with an average surface temperature difference, photosphere minus spots, of up to 1500 K for the polar spot and approximate to 800 K f or the equatorial spots. Since AG Dor is one of the slowest rotators (v sin i = 18 kms(-1)) that has ever been Doppler imaged, we present several test s to demonstrate the external consistency of our map.