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Astron. Astrophys. 342, 480-491 (1999)


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Physics of accretion onto young stars

III. Comparisons with observations

L. Siess, M. Forestini and C. Bertout

Observatoire de Grenoble, Laboratoire d'Astrophysique, Université Joseph Fourier, B.P. 53X, F-38041 Grenoble Cedex, France

Received 14 April 1998 / Accepted 12 November 1998

Abstract

We present new evolutionary sequences for long lasting accreting low-mass (0.1 [FORMULA] [FORMULA][FORMULA]) pre-main sequence stars. The calculations, performed for two different mass accretion rates, show that accretion accelerates the evolution of the star. The star has a smaller radius and goes down its convective track faster than in a standard scheme. Consequently, the age of a star, as given by its location on the Hertzsprung-Russell diagram, is lower than that of a non-accreting star. We discuss 2H and 7Li burning and show how accretion affects the surface abundance of these elements. Notably, we point out that deuterium must be present at the surface of accreting intermediate-mass stars. Finally, we estimate the age, mass and radius of a sample of T Tauri stars located in the Taurus Auriga star forming region.

Key words: accretion, accretion disks – stars: abundances – stars: evolution – stars: fundamental parameters – stars: pre-main sequence

Send offprint requests to: Lionel Siess

© European Southern Observatory (ESO) 1999

Online publication: February 22, 1999

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