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Abstract We apply the stellar locus method to synthetic (BP–RP)XPSPand (BP–G)XPSPcolors derived from corrected Gaia BP/RP (XP) spectra to obtain precise estimates of metallicity for about 100 million stars in the Milky Way (34 million giants in the color range 0.6 < (BP–RP)0 < 1.75 and 65 million dwarfs in the color range 0.2 < (BP–RP)0 < 1.5). The submillimagnitude precision of the derived synthetic stellar colors enables estimates of metallicity for stars as low as [Fe/H] ∼ −4. Multiple validation tests indicate that the typical metallicity precision is between 0.05 and 0.1 dex for both dwarfs and giants at [Fe/H] = 0, as faint asG ∼ 16, and decreases to 0.15–0.25 dex at [Fe/H] = −2.0. For −4.0 < [Fe/H] < −3.0, the typical metallicity precision decreases to on the order of 0.4–0.5 dex, based on the results from the reference sample. Our achieved precision is comparable to or better than previous efforts using the entire XP spectra and about 3 times better than our previous work based on Gaia EDR3 colors. This opens up new opportunities for investigations of stellar populations, the formation and chemical evolution of the Milky Way, the chemistry of stars and star clusters, and the identification of candidate stars for subsequent high-resolution spectroscopic follow-up. The catalog is publicly available at doi:10.12149/101548.
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A Blueprint for the Milky Way’s Stellar Populations. V. 3D Local Dust Extinction
Abstract Using a grid of empirically calibrated synthetic spectra developed in our previous study, we construct an all-sky 3D extinction map from the large collection of low-resolution XP spectra in Gaia DR3. Along each line of sight, with an area ranging from 0.2 to 13.4 deg2, we determine both the reddening and metallicity of main-sequence stars and model the foreground extinction up to approximately 3 kpc from the Sun. Furthermore, we explore variations in the total-to-selective extinction ratio in our parameter search and identify its mean systematic change across diverse cloud environments in both hemispheres. In regions outside the densest parts of the clouds, our reddening estimates are validated through comparisons with previous reddening maps. However, a notable discrepancy arises in comparison to other independent work based on XP spectra, which can be attributed to systematic offsets in their metallicity estimates. On the other hand, our metallicity scale exhibits reasonable agreement with the high-resolution spectroscopic abundance scale. We also assess the accuracy of the XP spectra by applying our calibrated models, and we confirm an increasing trend of flux overestimation at shorter wavelengths below 400 nm.
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- Award ID(s):
- 1927130
- PAR ID:
- 10506318
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal Supplement Series
- Volume:
- 272
- Issue:
- 1
- ISSN:
- 0067-0049
- Format(s):
- Medium: X Size: Article No. 20
- Size(s):
- Article No. 20
- Sponsoring Org:
- National Science Foundation
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