Accretion and disk dissipation time scales of pre-main-sequence stars: Insights from Gaia DR3 BP/RP spectra

Disk lifetimes around pre-main-sequence (PMS) stars are found to be ~ a few Myr with most stars appearing to lose their disks in ≲ 6 Myr, with a few (∼5-10%) lasting to about 10-12 Myr (e.g., Haisch et al. 2001; Hernandez et al. 2007; Ribas et al. 2014). So, the accretion process stops within a few Myr. However, recent studies have shown that accretion persists in cool PMSs even at an age of ≳ 20 Myr ( Silverberg et al. 2020). Therefore, a detailed study of the driving mechanism of accretion and its temporal evolution is critically important to our understanding of disk evolution and
planet formation around young stars. However, this study requires spectroscopic observation of a large number of PMS distributed over a large age and mass range. The recent Gaia Data Release 3 helps us to carry out the study by providing low-resolution BP/RP spectra as well as equivalent width of Hα (a secondary signature of accretion) for a few thousand PMS stars within a distance of 250 pc. At the Gaia Symposium, I will discuss how the accretion dissipation time scale of young PMS stars varies as a function of their mass and spectral types.