Bayesian Cross-matching of High Proper-motion Stars in Gaia DR2 and Photometric Metallicities for ∼1.7 million K and M Dwarfs

Abstract

We present a Bayesian method to cross-match 5,827,988 high proper-motion Gaia sources (μ > 40 mas yr−1) to various photometric surveys: Two Micron All Sky Survey, AllWISE data release from the Wide-field Infrared Explorer (WISE) mission, Galaxy Evolution Explorer, Radial Velocity Experiment, Sloan Digital Sky Survey, and Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). To efficiently associate these objects across catalogs, we develop a technique that compares the multidimensional distribution of all sources in the vicinity of each Gaia star to a reference distribution of random field stars obtained by extracting all sources in a region on the sky displaced 2′. This offset preserves the local field stellar density and magnitude distribution, allowing us to characterize the frequency of chance alignments. The resulting catalog with Bayesian probabilities >95% has a marginally higher match rate than current internal Gaia data release 2 (DR2) matches for most catalogs. However, a significant improvement is found with Pan-STARRS, where ∼99.8% of the sample within the Pan-STARRS footprint is recovered, as compared to a low ∼20.8% in Gaia DR2. Using these results, we train a Gaussian process regressor to calibrate two photometric metallicity relationships. For dwarfs of 3500 < T eff < 5280 K, we use metallicity values of 4378 stars from the Apache Point Observatory Galactic Evolution Experiment and Hejazi et al. to calibrate the relationship, producing results with a 1σ precision of 0.12 dex and few systematic errors. We then indirectly infer the metallicity of 4018 stars with 2850 < T eff < 3500 K, which are wide companions of primaries whose metallicities are estimated with our first regressor, to produce a relationship with a 1σ precision of 0.21 dex and significant systematic errors. Additional work is needed to better remove unresolved binaries from this second sample to reduce these systematic errors.

Vetting the “Lobster” Diagram: Searching for Unseen Companions in Wide Binaries Using NASA Space Exoplanet Missions

“…Another consequence is that in the "Lobster" diagram, metalrich stars are found near the origin at (0,0), while metal-poor stars are shifted to higher F OL values (above and right). To confirm this, we cross-match our sample of 4647 K+K wide binaries with the catalog of Medan et al (2021), which provides photometric metallicities for a large sample of K-dwarfs, including most of the primary components in our catalog. These metallicity values are color-coded in the "Lobster" diagram in Figure 15.…”

Detecting New Visual Binaries in Gaia DR3 with Gaia and Two Micron All Sky Survey (2MASS) Photometry. I. New Candidate Binaries within 200 pc of the Sun

“…Corresponding Gaia data for the 16 binaries targeted in this study. Below the distance and photometric data listed is for the primary, and the magnitude difference listed is between the primary and secondary as identified in Medan & Lépine (2023). run with multiple calibrator binaries to get the average pixel scale and orientation.…”

“…3 As the most recent Gaia photometry provided is for DR2, and the Gaia DR2 photometric bandpasses differs from the Gaia eDR3 photometry (Riello et al 2021), we transform their photometry using a cross-match between Gaia DR2 and eDR3 for stars within 200 pc. As the Gaia archive does not always provide a best match between these two catalogs, we use our method from Medan et al (2021) to create a catalog of high probability matches. Using this catalog of matches, we examine relations between Gaia eDR3 and DR2 photometry for each Gaia photometric band, as shown in Figure 2.…”

Vetting the Lobster Diagram: Searching for Unseen Companions in Wide Binaries using NASA Space Exoplanet Missions

“…To confirm this, we crossmatch our sample of 4647 K+K wide binaries with the catalog of Medan et al (2021) which provides photometric metallicities for a large sample of K-dwarfs, including most of the primary components in our catalog. These metallicity values are shown color-coded in the "Lobster diagram" in Figure 15.…”