Astron. Astrophys. 348, 533-541 (1999)

Resonances as the general cause of the outbursts in the symbiotic system AG Draconis

R. Gális ¹, L. Hric ¹, M. Friedjung ² and K. Petrík <sup>3

1</sup> Astronomical Institute of the Slovak Academy of Sciences, SK-059 60 Tatranská Lomnica, The Slovak Republic (galis@ta3.sk)
² Institut d'Astrophysique de Paris, 98bis Boulevard Arago, F-75014 Paris, France (friedjung@iap.fr)
³ Department of Mathematics, Informatics and Physics, Pedagogical Faculty, University of Trnava, SK-918 43 Trnava, The Slovak Republic

Received 23 February 1999 / Accepted 22 June 1999

Abstract

The general behaviour of the symbiotic system AG Dra is studied in the context of the long-term photometry monitoring and radial velocity analysis. Period analysis of the data gave two values of periods, and days for orbital motion and pulsations of cool giant respectively. The new orbital elements have been determined as well as the new orbital and pulsation ephemerides respectively. The ratio of the orbital to the pulsation period is actually very close to 14/9, so resonance might occur. We suggested, that this is the general cause of the recurrence time of the active stages. The pulsations of the cool component are very probably non-radial, so accretion by the white dwarf is particularly high when the material ejected due to the pulsations, is ejected in certain directions with respect to the line joining the two stars. The manifestations of this phenomena are the observed outbursts themselves.

Key words: stars: binaries: symbiotic stars: individual: AG Dra

Send offprint requests to: R. Gális

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Contents

• 1. Introduction
• 2. Observations
• 3. The method of analysis and its results
• 4. Discussion
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: July 26, 1999
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