The Stellar Spectra Factory (SSF) Based on SLAM

Abstract

An empirical stellar spectral library with large coverage of stellar parameters is essential for stellar population synthesis and studies of stellar evolution. In this work, we present Stellar Spectra Factory (SSF), a tool to generate empirical-based stellar spectra from arbitrary stellar atmospheric parameters. The relative flux-calibrated empirical spectra can be predicted by SSF given arbitrary effective temperature, surface gravity, and metallicity. SSF constructs the interpolation approach based on the Stellar LAbel Machine, using ATLAS-A library, which contains spectra covering from O type to M type, as the training data set. SSF is composed of four data-driven sub-models to predict empirical stellar spectra. Sub-model SSF-N can generate spectra from A to K type and some M giant stars, covering 3700 < T eff < 8700 K, 0 < < dex, and −1.5 < [M/H] < 0.5 dex. Sub-model SSF-gM is mainly used to predict M giant spectra with 3520 < T eff < 4000 K and −1.5 < [M/H] < 0.4 dex. Sub-model SSF-dM is for generating M dwarf spectra with 3295 < T eff < 4040 K, −1.0 < [M/H] < 0.1 dex. Sub-model SSF-B can predict B-type spectra with 9000 < T eff < 24,000 K and −5.2 < M G < 1.5 mag. The accuracy of the predicted spectra is validated by comparing the flux of predicted spectra to those with same stellar parameters selected from the known spectral libraries, MILES and MaStar. The averaged difference of flux over optical wavelength between the predicted spectra and the corresponding ones in MILES and MaStar is less than 5%. More verification is conducted between the magnitudes calculated from the integration of the predicted spectra and the observations in PS1 and APASS bands with the same stellar parameters. No significant systematic difference is found between the predicted spectra and the photometric observations. The uncertainty is 0.08 mag in the r band for SSF-gM when comparing with the stars with the same stellar parameters selected from PS1. The uncertainty becomes 0.31 mag in the i band for SSF-dM when comparing with the stars with the same stellar parameters selected from APASS.