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Astron. Astrophys. 351, 954-962 (1999)


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Accretion in Taurus PMS binaries: a spectroscopic study *

G. Duchêne 1, J.-L. Monin 1,2, J. Bouvier 1 and F. Ménard 1,3

1 Laboratoire d'Astrophysique, Observatoire de Grenoble, Université Joseph Fourier, B.P. 53, 38041 Grenoble Cedex 9, France
2 Institut Universitaire de France
3 Canada-France-Hawaii Telescope Corporation, P.O. Box 1597, Kamuela HI 96743, USA

Received 11 February 1999 / Accepted 21 September 1999

Abstract

We present low-resolution optical spectra of each component of 10 T Tauri (TT) binary systems with separations ranging from [FORMULA] to [FORMULA] and located in the Taurus star-forming region. We derive the spectral type and H[FORMULA] equivalent width of each component.

Complementing these results with those of Monin et al. (1998) yields a sample of 14 binaries and one triple system, with resolved spectroscopy and/or near-infrared photometry. We find that mixed binaries (CTTS+WTTS) are rare, representing only 15-20% of the systems in the separation range of [FORMULA] to [FORMULA]. Supplementing these results with those of Hartigan et al. (1994) and Prato & Simon (1997), we show that the trend of binary TTS to be twins holds to separations up to [FORMULA]. This is unlikely to be the result of random pairing, and confirms previous results that both stars in young binaries accrete over the same time span.

In binary systems where both stars are still accreting, our measurements show that the most massive star is usually the component with the largest accretion rate by up to a factor of 10, as determined from the H[FORMULA] luminosity.

Key words: stars: binaries: general – stars: circumstellar matter – stars: formation – stars: pre-main sequence – accretion, accretion disks

* Based on observations made with the Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii

Send offprint requests to: G. Duchêne (Gaspard.Duchene@obs.ujf-grenoble.fr)

© European Southern Observatory (ESO) 1999

Online publication: November 16, 1999

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