The Lithium Abundances from the Large Sky Area Multi-object Fiber Spectroscopic Telescope Medium-resolution Survey. I. The Method

One of the purposes of taking spectra for millions of stars through the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution survey (MRS) is to obtain the elemental abundances, so that one can trace the origin and evolution for the element of interests. Lithium is one of such elements of great importance, which exhibits many puzzling behaviors. Investigating the lithium abundances to a uniquely large sample of stars is essential to understand its origin and evolution. In this paper, we present the lithium abundances obtained from the LAMOST MRS spectra calculated by the template-matching method. Our data set consists of 294,857 spectra that corresponds to 165,479 stars with a resolution power of Delta lambda/lambda similar to 7500. We compared the lithium abundances derived from our work with those using the high-resolution spectra and found a good consistence. The errors of lithium abundances are discussed. Our results suggest that the distribution of lithium abundances show two clear peaks at +2.6 and +1.0 dex, respectively. This sample is potentially important for investigating physical mechanisms occurring inside stars that alter the surface lithium abundance.