1. Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost
- Author
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Khalatyan, A., Anders, F., Chiappini, C., Queiroz, A. B. A., Nepal, S., Ponte, M. dal, Jordi, C., Guiglion, G., Valentini, M., Elipe, G. Torralba, Steinmetz, M., Pantaleoni-González, M., Malhotra, S., Jiménez-Arranz, Ó., Enke, H., Casamiquela, L., and Ardèvol, J.
- Subjects
Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
We explore the feasibility of using machine-learning regression as a method of extracting basic stellar parameters and line-of-sight extinctions, given spectro-photometric data. To this end, we build a stable gradient-boosted random-forest regressor (xgboost), trained on spectroscopic data, capable of producing output parameters with reliable uncertainties from Gaia DR3 data (most notably the low-resolution XP spectra) without ground-based spectroscopic observations. Using Shapley additive explanations, we are able to interpret how the predictions for each star are influenced by each data feature. For the training and testing of the network, we use high-quality parameters obtained from the StarHorse code for a sample of around eight million stars observed by major spectroscopic surveys (APOGEE, GALAH, LAMOST, RAVE, SEGUE, and GES), complemented by curated samples of hot stars, very metal-poor stars, white dwarfs, and hot sub-dwarfs. The training data cover the whole sky, all Galactic components, and almost the full magnitude range of the Gaia DR3 XP sample of more than 217 million objects that also have parallaxes. We achieve median uncertainties (at $G\approx16$) of 0.20 mag in V-band extinction, 0.01 dex in logarithmic effective temperature, 0.20 dex in surface gravity, 0.18 dex in metallicity, and $12\%$ in mass (over the full Gaia DR3 XP sample, with considerable variations in precision as a function of magnitude and stellar type). We succeed in predicting competitive results based on Gaia DR3 XP spectra compared to classical isochrone fitting methods we employed in earlier work, especially for the parameters $A_V$, $T_{\rm eff}$, and metallicity. Finally, we showcase some applications of this new catalogue (e.g. extinction maps, metallicity trends in the Milky Way, extended maps of young massive stars, metal-poor stars, and metal-rich stars). [abridged], Comment: Resubmitted to A&A after minor revisions. 13 pages, 13 figures + references & appendices. Data available at https://data.aip.de/projects/shboost2024.html
- Published
- 2024