Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based Principal Component Analysis

TL;DR

This paper introduces a kernel-based principal component analysis method to accurately estimate stellar atmospheric parameters, elemental abundances, and absolute magnitudes from LAMOST spectra, enabling large-scale stellar characterization.

Contribution

It presents the first direct estimation of absolute magnitudes and C/N abundances from spectra using a multivariate regression approach, improving parameter accuracy for large stellar datasets.

Findings

Achieves ~100K precision for T_eff at SNR > 50

Provides reliable [C/H] and [N/H] estimates from LAMOST data

First to estimate absolute magnitudes directly from spectra

Abstract

Accurate determination of stellar atmospheric parameters and elemental abundances is crucial for Galactic archeology via large-scale spectroscopic surveys. In this paper, we estimate stellar atmospheric parameters -- effective temperature T_{\rm eff}, surface gravity log g and metallicity [Fe/H], absolute magnitudes M_V and M_{Ks}, {\alpha}-element to metal (and iron) abundance ratio [{\alpha}/M] (and [{\alpha}/Fe]), as well as carbon and nitrogen abundances [C/H] and [N/H] from the LAMOST spectra with amultivariate regressionmethod based on kernel-based principal component analysis, using stars in common with other surveys (Hipparcos, Kepler, APOGEE) as training data sets. Both internal and external examinations indicate that given a spectral signal-to-noise ratio (SNR) better than 50, our method is capable of delivering stellar parameters with a precision of ~100K for Teff, ~0.1 dex for log g, 0.3 -- 0.4mag for M_V and M_{Ks}, 0.1 dex for [Fe/H], [C/H] and [N/H], and better than 0.05 dex for [{\alpha}/M] ([{\alpha}/Fe]). The results are satisfactory even for a spectral SNR of 20. The work presents first determinations of [C/H] and [N/H] abundances from a vast data set of LAMOST, and, to our knowledge, the first reported implementation of absolute magnitude estimation directly based on the observed spectra. The derived stellar parameters for millions of stars from the LAMOST surveys will be publicly available in the form of value-added catalogues.