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Astron. Astrophys. 320, 586-593 (1997)


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Discovery of two short-period eclipsing binaries with active components *

G. Cutispoto 1, M. Kürster 2, 3, S. Messina 4, M. Rodonò 1, 4 and G. Tagliaferri 5

1 Osservatorio Astrofisico di Catania, Viale A.Doria 6, I-95125 Catania, Italy
2 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, D-85740 Garching, Germany
3 Institut für Astronomie, Universität Wien, A-1180 Wien, Austria
4 Istituto di Astronomia, Universita degli Studi, Viale A.Doria 6, I-95125 Catania, Italy
5 Osservatorio Astronomico di Brera, Via Bianchi 46, I-20121 Merate, Italy

Received 2 April 1996 / Accepted 23 September 1996

Abstract

We present high-precision [FORMULA] photometry as well as soft X-ray light curves for the visual triple system HD 9770 and the visual binary HD 195434, obtained at the European Southern Observatory and extracted from the ROSAT all-sky survey, respectively. The optical photometry revealed that in both systems one component is a very short-period eclipsing binary showing also BY Dra-type variability. We have computed accurate orbital periods, deduced approximate physical parameters, spectral classifications, distances and X-ray luminosities and identified which component of each visual system is responsible for the optical variability. Futhermore, we find that both systems are variable in X-rays, but no correlation with the optical variability is seen.

Key words: stars: activity – stars: late-type – stars: variables – binaries: eclipsing – X-rays: stars – techniques: photometry

* based on data collected at the European Southern Observatory, La Silla, Chile

Send offprint requests to: Giuseppe Cutispoto gcutispoto@alpha4.ct.astro.it

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998

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