Homogeneous Stellar Atmospheric Parameters and 22 Elemental Abundances for FGK Stars Derived from LAMOST Low-resolution Spectra with DD-PAYNE

Abstract A deep understanding of our Galaxy calls for detailed decomposition of its stellar populations via their chemical fingerprints. This requires precise stellar abundances of many elements for a large number of stars. Here, we present an updated catalog of stellar labels derived from Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low-resolution spectra in a physics-sensible and rigorous manner with DD-Payne , taking labels from high-resolution spectroscopy as a training set. The catalog contains atmospheric parameters for 6.4 million stars released in LAMOST DR9, and abundances for 22 elements, namely, C, N, O, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Ni, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, and Eu, for nearly 3.6 million stars with spectral signal-to-noise ratio (S/N) higher than 20. The [Fe/H] is valid down to ≃ −4.0, while elemental abundance ratios [X/Fe] are mostly valid for stars with [Fe/H] ≳ −2.0. Measurement errors in these labels are sensitive to and almost inversely proportional with S/N. For stars with S/N &gt; 50, we achieved a typical error of 30 K in T eff , 0.07 dex in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mspace width="0.25em"/> <mml:mi>g</mml:mi> </mml:math> , ∼0.05 dex in abundances for most elements with atomic number smaller than Sr, and 0.1–0.2 dex for heavier elements. Homogenization to the label estimates is carried out via dedicated internal and external calibration. In particular, the nonlocal thermal equilibrium effect is corrected for the [Fe/H] estimates, the T eff is calibrated to the infrared flux method scale, and the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mspace width="0.25em"/> <mml:mi>g</mml:mi> </mml:math> is validated with asteroseismic measurements. The elemental abundances are internally calibrated using wide binaries, eliminating systematic trend with effective temperature. The catalog is publicly available.