Estimating Atmospheric Parameters of DA White Dwarf Stars with Deep Learning

TL;DR

This paper presents a deep learning approach to estimate atmospheric parameters of DA white dwarf stars directly from spectral data, achieving high accuracy and broad applicability, including lower-resolution spectra.

Contribution

The authors develop a deep learning model that estimates Teff and log g of DA white dwarfs directly from spectral pixels, bypassing traditional model-dependent fitting methods.

Findings

RMSE for Teff is approximately 900 K.

RMSE for log g is approximately 0.1 dex.

Applicable to spectra with resolution down to 200.

Abstract

The determination of atmospheric parameters of white dwarf stars (WDs) is crucial for researches on them. Traditional methodology is to fit the model spectra to observed absorption lines and report the parameters with the lowest $\chi ^2$ error, which strongly relies on theoretical models that are not always publicly accessible. In this work, we construct a deep learning network to model-independently estimate Teff and log g of DA stars (DAs), corresponding to WDs with hydrogen dominated atmospheres. The network is directly trained and tested on the normalized flux pixels of full optical wavelength range of DAs spectroscopically confirmed in the Sloan Digital Sky Survey (SDSS). Experiments in test part yield that the root mean square error (RMSE) for Teff and log g approaches to 900 K and 0.1 dex, respectively. This technique is applicable for those DAs with Teff from 5000 K to 40000 K and log g from 7.0 dex to 9.0 dex. Furthermore, the applicability of this method is verified for the spectra with degraded resolution $\sim 200$. So it is also practical for the analysis of DAs that will be detected by the Chinese Space Station Telescope (CSST).