Disc evolution and the relationship between $L_{\mathrm{acc}}$ and $L_{\ast }$ in T Tauri stars

Abstract

We investigate the evolution of accretion luminosity $L_{\mathrm{acc}}$ and stellar luminosity $L_{\ast }$ in pre-mainsequence stars. We make the assumption that when the star appears as a Class II object, the major phase of accretion is long past, and the accretion disc has entered its asymptotic phase. We use an approximate stellar evolution scheme for accreting pre-mainsequence stars based on Hartmann, Cassen & Kenyon, 1997. We show that the observed range of values $k=L_{\mathrm{acc}}/L_{\ast }$ between 0.01 and 1 can be reproduced if the values of the disc mass fraction $M_{\mathrm{disc}}/M_{\ast }$ at the start of the T Tauri phase lie in the range 0.01 -- 0.2, independent of stellar mass. We also show that the observed upper bound of $L_{\mathrm{acc}}\sim L_{\ast }$ is a generic feature of such disc accretion. We conclude that as long as the data uniformly fills the region between this upper bound and observational detection thresholds, then the degeneracies between age, mass and accretion history severely limit the use of this data for constraining possible scalings between disc properties and stellar mass.

To appear in MNRAS

References in corpus (4)

• Accretion in the Rho-Oph pre-main sequence stars
• Accretion in protoplanetary disks: the imprint of core properties
• The stellar mass-accretion rate relation in T Tauri stars and brown dwarfs
• The $\dot{M}-M$ relationship in pre-main sequence stars

Cited by in corpus (6)

• X-Shooter spectroscopy of young stellar objects in Lupus: Accretion properties of class II and transitional objects
• Measuring tiny mass accretion rates onto young brown dwarfs
• POISSON project - III - Investigating the evolution of the mass accretion rate
• GIARPS High-resolution Observations of T Tauri stars (GHOsT). III. A pilot study of stellar and accretion properties
• Star formation and accretion rates within 500 pc as traced by Gaia DR3 XP spectra
• Probing accretion and stellar properties in the Orion Nebula with VLT/X-Shooter