Validation of the Gaia Early Data Release 3 Parallax Zeropoint Model with Asteroseismology
Abstract
Gaia Early Data Release 3 (EDR3) provides trigonometric parallaxes for 1.5 billion stars, with reduced systematics compared to Gaia Data Release 2 and reported precisions better by up to a factor of 2. New to EDR3 is a tentative model for correcting the parallaxes of magnitude, position, and colordependent systematics for five and sixparameter astrometric solutions, Z_{5} and Z_{6}. Using a sample of over 2000 firstascent red giant branch stars with asteroseismic parallaxes, I perform an independent check of the Z_{5} model in a Gaia magnitude range of 9 ≲ G ≲ 13 and color range of 1.4 μm^{1} ≲ ν_{eff} ≲ 1.5 μm^{1}. This analysis therefore bridges the Gaia team's consistency check of Z_{5} for G > 13 and indications from independent analysis using Cepheids of a ≈15 μas overcorrection for G < 11. I find overcorrection sets in at G ≲ 10.8, such that Z_{5}corrected EDR3 parallaxes are larger than asteroseismic parallaxes by 15 ± 3 μas. For G ≳ 10.8, EDR3 and asteroseismic parallaxes in the Kepler field agree up to a constant consistent with expected spatial variations in EDR3 parallaxes after a linear, colordependent adjustment. I also infer an average underestimation of EDR3 parallax uncertainties in the sample of 22% ± 6%, consistent with the Gaia team's estimates at similar magnitudes and independent analysis using wide binaries. Finally, I extend the Gaia team's parallax spatial covariance model to brighter magnitudes (G < 13) and smaller scales (down to ≈0°1), where systematic EDR3 parallax uncertainties are at least ≈34 μas.
 Publication:

The Astronomical Journal
 Pub Date:
 May 2021
 DOI:
 10.3847/15383881/abe936
 arXiv:
 arXiv:2101.07252
 Bibcode:
 2021AJ....161..214Z
 Keywords:

 Parallax;
 Asteroseismology;
 Red giant stars;
 Stellar distance;
 1197;
 73;
 1372;
 1595;
 Astrophysics  Astrophysics of Galaxies;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 Published in AJ