Over the past 14 billion years, our Galaxy has assembled billions of stars into a few major structural components, the disk(s), the halo, and the barred bulge. Unraveling the assembly and evolution history of these grand-designed structures is an ambitious goal of a number of ongoing large-scale stellar surveys, such as Gaia, LAMOST, SDSS/APOGEE etc. The survey data set, in terms of both the number of stars and the coverage of the stellar parameter space, is expanding rapidly. While this data burst brings great discovery space, it also comes with great challenges for the data analysis, in particular for maximally extracting stellar physical information from low-resolution survey spectra.
In the talk, I will review our efforts on determining stellar labels for stars across a huge parameter space from the LAMOST low-resolution survey spectra. As a result, precise stellar age, atmospheric parameters, and elemental abundances for millions of stars are available. These extensive stellar labels have greatly promoted the science for a broad of area, from the Milky Way and near-field cosmology to stars and planets. As an example, I will particularly tell the wonderful story of our Galaxy’s early formation history. Our study reveals that our Galaxy has began to form its old disk 13 billion ago, much earlier than previous knowleadge.
