Physics of accretion onto young stars III. Comparisons with observations

We present new evolutionary sequences for long lasting accreting low-mass (0.1 M ≤ M ≤ 2.5M ) 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 HertzsprungRussell 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.