LAMA: LAMOST Medium-Resolution Spectral Analysis Pipeline

TL;DR

The paper introduces LAMA, a pipeline for analyzing medium-resolution spectra from LAMOST to accurately determine stellar parameters, enabling large-scale stellar and galactic studies.

Contribution

LAMA is a new spectral analysis pipeline that reliably estimates stellar parameters from LAMOST medium-resolution spectra, matching high-resolution results.

Findings

Achieves Teff accuracy of 75 K for high S/N spectra.

Metallicity estimates with 0.12 dex precision.

Derived parameters for nearly 500,000 stars.

Abstract

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has obtained more than 23 million spectra, opening an unprecedented opportunity to study stellar physics, as well as the formation and evolution of our Milky Way. In order to obtain the accurate stellar parameters, we develop a LAMOST Medium-Resolution Spectral Analysis Pipeline (LAMA), which estimates the stellar parameters from the LAMOST medium-resolution spectra, including the effective temperature (Teff), surface gravity (logg), metallicity ([Fe/H]), radial velocity, and rotational velocity (vsini). LAMA estimates these parameters utilizing the template-matching method. The comparison between our results and those from the high-resolution ones, including APOGEE, GALAH, and PASTEL, shows no obvious bias, indicating the reliability of our results. The accuracy of Teff and [Fe/H] can reach 75 K and 0.12 dex, respectively, for the LAMOST Medium-Resolution Spectroscopic Survey (MRS) spectra with a signal-to-noise ratio higher than 10. For dwarfs, the uncertainty of logg is around 0.17 dex, while, for giants, it ranges from 0.18 to 0.30 dex, with the errors decreasing as logg increases. Using LAMA for the LAMOST-MRS spectra, we estimate the stellar parameters of 497,412 stars. This sample will be very helpful for investigating the formation and evolution of our Galaxy.