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1. A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties

   https://doi.org/10.1093/mnras/stab323  

   El-Badry, Kareem ; Rix, Hans-Walter ; Heintz, Tyler M ( July 2021 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We construct from Gaia eDR3 an extensive catalogue of spatially resolved binary stars within ≈1 kpc of the Sun, with projected separations ranging from a few au to 1 pc. We estimate the probability that each pair is a chance alignment empirically, using the Gaia catalogue itself to calculate the rate of chance alignments as a function of observables. The catalogue contains 1.3 (1.1) million binaries with >90 per cent (>99 per cent) probability of being bound, including 16 000 white dwarf – main-sequence (WD + MS) binaries and 1400 WD + WD binaries. We make the full catalogue publicly available, as well as the queries and code to produce it. We then use this sample to calibrate the published Gaia DR3 parallax uncertainties, making use of the binary components’ near-identical parallaxes. We show that these uncertainties are generally reliable for faint stars (G ≳ 18), but are underestimated significantly for brighter stars. The underestimates are generally $\leq30{{\ \rm per\ cent}}$ for isolated sources with well-behaved astrometry, but are larger (up to ∼80 per cent) for apparently well-behaved sources with a companion within ≲4 arcsec, and much larger for sources with poor astrometric fits. We provide an empirical fitting function to inflate published σϖ values for isolated sources. The publicmore »catalogue offers wide ranging follow-up opportunities: from calibrating spectroscopic surveys, to precisely constraining ages of field stars, to the masses and the initial–final mass relation of WDs, to dynamically probing the Galactic tidal field.« less
2. The First Polluted White Dwarf from Gaia DR2: The Cool DAZ Gaia J1738–0826

   https://doi.org/10.3847/2515-5172/aacf41  

   Melis, Carl ; Zuckerman, B. ; Dufour, P. ; Song, I. ; Klein, B. ( April 2018 , Research Notes of the AAS)
3. Measuring the Absolute Total Intrinsic Redshifts (Surface Gravity Plus the Convective Blueshift) of the Main-sequence Stars and Red Giants using Gaia Data

   https://doi.org/10.3847/1538-4357/aaf6aa  

   Dai, De-Chang ; Li, ZhiGang ; Stojkovic, Dejan ( January 2019 , The Astrophysical Journal)
4. Search for globular clusters associated with the Milky Way dwarf galaxies using Gaia DR2

   https://doi.org/10.1093/mnras/staa3297  

   Huang, Kuan-Wei ; Koposov, Sergey E ( November 2020 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We report the result of searching for globular clusters (GCs) around 55 Milky Way (MW) satellite dwarf galaxies within the distance of 450 kpc from the Galactic Centre except for the Large and Small Magellanic Clouds and the Sagittarius dwarf. For each dwarf, we analyse the stellar distribution of sources in Gaia DR2, selected by magnitude, proper motion, and source morphology. Using the kernel density estimation of stellar number counts, we identify 11 possible GC candidates. Cross-matched with existing imaging data, all 11 objects are known either GCs or galaxies and only Fornax GC 1–6 among them are associated with the targeted dwarf galaxy. Using simulated GCs, we calculate the GC detection limit $M_{\rm V}^{\rm lim}$ that spans the range from $M_{\rm V}^{\rm lim}\sim -7$ for distant dwarfs to $M_{\rm V}^{\rm lim}\sim 0$ for nearby systems. Assuming a Gaussian GC luminosity function, we compute that the completeness of the GC search is above 90 per cent for most dwarf galaxies. We construct the 90 per cent credible intervals/upper limits on the GC specific frequency SN of the MW dwarf galaxies: 12 < SN < 47 for Fornax, SN < 20 for the dwarfs with −12 < MV < −10, SNmore »< 30 for the dwarfs with −10 < MV < −7, and SN < 90 for the dwarfs with MV > −7. Based on SN, we derive the probability of galaxies hosting GCs given their luminosity, finding that the probability of galaxies fainter than MV = −9 to host GCs is lower than 0.1.« less
5. DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

   https://doi.org/10.1093/mnras/sty1419  

   Agnello, A ; Lin, H ; Kuropatkin, N ; Buckley-Geer, E ; Anguita, T ; Schechter, P L ; Morishita, T ; Motta, V ; Rojas, K ; Treu, T ; et al ( June 2018 , Monthly Notices of the Royal Astronomical Society)