On the effect of overshooting as predicted by the modelling of the pre-main sequence evolution of a 2 solar-mass star

• Type: Article in International Scientific Journal
• Date: 2006

Authors

J.P. Marques (Author) FCUP; Mário João P. F. G. Monteiro (Author) FCUP; João Fernandes (Author) FCUP

Journal

Title: Monthly Notices of the Royal Astronomical Society

Vol. 371

Pages: 293-302

ISSN: 0035-8711

Publisher: Oxford University Press

Indexing

ISI Web of Science

Scientific classification

FOS: Natural sciences > Physical sciences

CORDIS: Physical sciences > Astronomy ; Physical sciences > Astronomy > Astrophysics ; Physical sciences

Other information

Resumo (PT): We discuss the effects of convective overshooting in the pre-main-sequence (PMS) evolution of intermediate-mass stars, by analysing in detail the early evolution towards the main sequence of a 2 M⊙ stellar model. These effects can be extremely important in the end of the PMS, when the abundances in CNO elements approach the equilibrium in the centre. We provide a possible physical explanation on why a moderate amount of overshooting produces, as the star approaches the zero-age main-sequence, an extra loop in the evolutionary tracks on the Hertzsprung–Russell diagram. An interesting feature is that there is a very well defined amount of overshooting (for a given stellar mass and chemical composition) beyond which a loop is produced. For smaller amounts of overshooting such a loop does not take place and the evolutionary tracks are similar to those found in the literature. The amount of overshooting needed to produce the loop decreases with stellar mass. We discuss the underlining physical reasons for the behaviour predicted by the evolution models and argue that it provides a crucial observational test for convective overshooting in the core of intermediate-mass stars.

Abstract (EN): We discuss the effects of convective overshooting in the pre-main-sequence (PMS) evolution of intermediate-mass stars, by analysing in detail the early evolution towards the main sequence of a 2 M⊙ stellar model. These effects can be extremely important in the end of the PMS, when the abundances in CNO elements approach the equilibrium in the centre. We provide a possible physical explanation on why a moderate amount of overshooting produces, as the star approaches the zero-age main-sequence, an extra loop in the evolutionary tracks on the Hertzsprung–Russell diagram. An interesting feature is that there is a very well defined amount of overshooting (for a given stellar mass and chemical composition) beyond which a loop is produced. For smaller amounts of overshooting such a loop does not take place and the evolutionary tracks are similar to those found in the literature. The amount of overshooting needed to produce the loop decreases with stellar mass. We discuss the underlining physical reasons for the behaviour predicted by the evolution models and argue that it provides a crucial observational test for convective overshooting in the core of intermediate-mass stars.

Language: English

Type (Professor's evaluation): Scientific