Calibration of LAMOST Stellar Surface Gravities Using the Kepler Asteroseismic Data

TL;DR

This study calibrates LAMOST stellar surface gravities using Kepler asteroseismic data, revealing systematic overestimations and providing empirical relations for improved stellar parameter accuracy.

Contribution

It introduces empirical calibration relations for LAMOST logg values based on Kepler asteroseismic data, enhancing the accuracy of stellar surface gravity measurements.

Findings

LAMOST logg overestimated by up to 0.5 dex for giants

Clear trends between LAMOST-seismic logg differences and spectroscopic parameters

Calibrated relations improve stellar distance estimations

Abstract

Asteroseismology is a powerful tool to precisely determine the evolutionary status and fundamental properties of stars. With the unprecedented precision and nearly continuous photometric data acquired by the NASA Kepler mission, parameters of more than 10$^4$ stars have been determined nearly consistently. However, most studies still use photometric effective temperatures (Teff) and metallicities ([Fe/H]) as inputs, which are not sufficiently accurate as suggested by previous studies. We adopted the spectroscopic Teff and [Fe/H] values based on the LAMOST low-resolution spectra (R~1,800), and combined them with the global oscillation parameters to derive the physical parameters of a large sample of stars. Clear trends were found between {\Delta}logg(LAMOST - seismic) and spectroscopic Teff as well as logg, which may result in an overestimation of up to 0.5 dex for the logg of giants in the LAMOST catalog. We established empirical calibration relations for the logg values of dwarfs and giants. These results can be used for determining the precise distances to these stars based on their spectroscopic parameters.