Volume 370, Number 1, April IV 2001
|Page(s)||218 - 229|
|Section||Stellar structure and evolution|
|Published online||15 April 2001|
A study of the chromospherically active binaries UX Fornacis and AG Doradus*
Astrophysical Institute Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
2 Institute for Astronomy, University of Vienna, Türkenschanzstraße 17, 1180 Wien, Austria e-mail: AWashuettl / KStrassmeier@aip.de
Corresponding author: A. Washuettl, firstname.lastname@example.org
Accepted: 29 January 2001
This paper presents a time-series spectrum analysis of the two chromospherically active binary stars, UX Fornacis and AG Doradus. To investigate the rotational behaviour, in combination with activity in the Hα line, we obtained almost 40 high-resolution, high- spectra for each system. Both binaries, UX For and AG Dor, show Hα of the primary star in absorption but filled in by chromospheric emission while the Hα line of the secondaries appear in pure emission. Line variations are seen and are approximately 5-σ detections but are not linked to the orbital nor the rotational periods and seem to be erratic. We obtained new orbital elements for both systems and used them in combination with Hipparcos parallaxes and our Hα-spectrum synthesis to determine absolute parameters. We present the first Doppler image of the AG Dor primary using line-profile variations of the Fe i λ6546 line. The image reveals a cool polar feature and three equatorial spots with an average surface temperature difference, photosphere minus spots, of up to 1500 K for the polar spot and ≈800 K for the equatorial spots. Since AG Dor is one of the slowest rotators ( km s-1) that has ever been Doppler imaged, we present several tests to demonstrate the external consistency of our map.
Key words: stars: activity / stars: atmospheres / stars: imaging / stars: AG Dor, UX For / stars: late-type / binaries: close
© ESO, 2001
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.