Emission line star catalogues post-Gaia DR3: A validation of Gaia DR3 data using LAMOST OBA emission catalogue

TL;DR

This study validates Gaia DR3 emission-line star data using LAMOST spectra, providing improved empirical relations for parameter conversion and highlighting limitations in Gaia's emission-line detection.

Contribution

The paper offers a comprehensive validation of Gaia DR3 emission-line star parameters with LAMOST data and develops new empirical relations for parameter conversion.

Findings

Gaia DR3 classifications are reasonably consistent with LAMOST.

Astrophysical parameters from Gaia esphs are more accurate than other Gaia modules.

Weak Hα emitters are often missed in Gaia BP/RP spectra.

Abstract

Gaia DR3 and further releases have the potential to identify and categorise new emission-line stars in the Galaxy. We perform a comprehensive validation of astrophysical parameters from Gaia DR3 with the spectroscopically estimated emission-line star parameters from LAMOST OBA emission catalogue. We compare different astrophysical parameters provided by Gaia DR3 with those estimated using LAMOST spectra. By using a larger sample of emission-line stars, we perform a global polynomial and piece-wise linear fit to update the empirical relation to convert Gaia DR3 pseudo-equivalent width to observed equivalent width, after removing the weak emitters from the analysis. We find that the emission-line source classifications given by DR3 is in reasonable agreement with the classification from LAMOST OBA emission catalogue. The astrophysical parameters estimated by esphs module from Gaia DR3 provides a better estimate when compared to gspphot and gspspec. A second-degree polynomial relation is provided along with piece-wise linear fit parameters for the equivalent width conversion. We notice that the LAMOST stars with weak H{\alpha} emission are not identified to be in emission from BP/RP spectra. This suggests that emission-line sources identified by Gaia DR3 is incomplete. In addition, Gaia DR3 provides valuable information about the binary and variable nature of a sample of emission-line stars.