ABYSS. II. LAMOST pre-main-sequence candidates

These lines, such as LiI, which directly indicates stellar youth, or optical HI and CaII, which in emission indicate activity associated with stellar youth, are commonly seen in YSOs. We observe several notable differences in the properties of these lines between YSOs and the field stars.

Using these data, we devise a set of criteria through which it is possible to confirm the youth of stars that have been observed by the ABYSS program, as well as to identify likely young stars that have serendipitously been observed by other programs. We examine the decrement of H lines seen in emission in CTTSs, and estimate the properties of the accretion stream that is responsible for the production of these lines. Finally, we examine the evolution of LiI as a function of age, and characterize the scatter in its abundance that appears to be intrinsic in young M-dwarfs.