Evidence for a Systematic Offset of −80 μas in the Gaia DR2 Parallaxes

By Keivan G. Stassun, G. Torres. Astrophysical Journal, 2018

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We reprise the analysis of Stassun & Torres, comparing the parallaxes of the eclipsing binaries reported in that paper to the parallaxes newly reported in the Gaia second data release (DR2). We find evidence for a systematic offset of −82 ± 33 μas, in the sense of the Gaia parallaxes being too small, for brightnesses (G ≲ 12) and for distances (0.03–3 kpc) in the ranges spanned by the eclipsing binary sample. The offset does not appear to depend strongly on distance within this range, though there is marginal evidence that the offset increases (becomes slightly more negative) for distances ≳1 kpc, up to the 3 kpc distances probed by the test sample. The offset reported here is consistent with the expectation that global systematics in the Gaia DR2 parallaxes are below 100 μas.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/0a60a04088be9cea7472fee8d40cc7027e4f24d1

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Citations in the corpus

Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 (2019, background): “It is well known that the parallaxes delivered by Gaia DR2 are not entirely free from systematics (Gaia Collaboration 2018b; Lindegren et al. 2018; Stassun & Torres 2018; Zinn et al. 2019; Khan et al. 2019)2.”
A Gaia DR2 view of the open cluster population in the Milky Way (2018, result): “As reported in Lindegren et al. (2018) and Arenou et al. (2018; and confirmed by Riess et al. 2018; Zinn et al. 2018; Stassun & Torres 2018), the Gaia DR2 parallaxes are affected by a zero-point offset.”
Kinematics in Young Star Clusters and Associations with Gaia DR2 (2018, result): “…cases, the uncertainties on median parallaxes are 2 Several papers have proposed correction factors for systematic errors in Gaia astrometry (e.g., Stassun & Torres 2018; Muraveva et al. 2018; Kounkel et al. 2018), all of which are consistent with the systematic uncertainties reported by…”