EDP Sciences
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Volume 409, Number 1, October I 2003
Page(s) 245 - 250
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20031064

A&A 409, 245-250 (2003)
DOI: 10.1051/0004-6361:20031064

Fundamental parameters and origin of the very eccentric binary 41 Dra

A. Tokovinin1, Y. Y. Balega2, E. A. Pluzhnik2, N. I. Shatsky3, N. A. Gorynya4 and G. Weigelt5

1  Cerro-Tololo Inter-American Observatory, Casilla 603, La Serena, Chile
2  Special Astrophysical Observatory, Nizhnij Arkhyz, Zelenchuk region, Karachai-Cherkesia 369167, Russia
3  Sternberg Astronomical Institute, 13 Universitetskii pr., 119992 Moscow, Russia
4  Institute of Astronomy of Russian Acad. Sci., 48 Pyatnitskaya St., 109017 Moscow, Russia
5  Max-Planck-Institut für radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

(Received 17 March 2003 / Accepted 28 May 2003 )

The evolutionary status and origin of the most eccentric known binary in a quadruple system, 41 Dra ( e=0.9754, period 3.413 yr), are discussed. New observations include the much improved combined speckle-interferometric orbit, resolved photometry of the components and their spectroscopic analysis. The age of the system is  $2.5 \pm 0.2$ Gyr; all four components are likely coeval. The high eccentricity of the orbit together with known age and masses provide a constraint on the tidal circularization theory: it seems that the eccentric orbit survived because the convective zones of the F-type dwarfs were very thin. Now as the components of 41 Dra are leaving the Main Sequence, their increased interaction at each periastron passage may result in detectable changes in period and eccentricity.

Key words: stars: binaries: visual -- stars: binaries: spectroscopic -- stars: formation -- stars: individual: HD 166866, HD 166865

Offprint request: A. Tokovinin, atokovinin@ctio.noao.edu

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