Estimating distances from parallaxes. V.
Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3

C.A.L. Bailer-Jones, J. Rybizki, M. Fouesneau, M. Demleitner, R. Andrae

Stellar distances constitute a foundational pillar of astrophysics. The publication of 1.47 billion stellar parallaxes from Gaia is a major contribution to this. Yet despite Gaia's precision, the majority of these stars are so distant or faint that their fractional parallax uncertainties are large, thereby precluding a simple inversion of parallax to provide a distance. Here we take a probabilistic approach to estimating stellar distances that uses a prior constructed from a three-dimensional model of our Galaxy. This model includes interstellar extinction and Gaia's variable magnitude limit. We infer two types of distance. The first, geometric, uses the parallax together with a direction-dependent prior on distance. The second, photogeometric, additionally uses the colour and apparent magnitude of a star, by exploiting the fact that stars of a given colour have a restricted range of probable absolute magnitudes (plus extinction). Tests on simulated data and external validations show that the photogeometric estimates generally have higher accuracy and precision for stars with poor parallaxes. We provide a catalogue of 1.47 billion geometric and 1.35 billion photogeometric distances together with asymmetric uncertainty measures. Our estimates are quantiles of a posterior probability distribution, so they transform invariably and can therefore also be used directly in the distance modulus (5log10(r)-5). The catalogue may be downloaded or queried using ADQL at various sites where it can also be cross-matched with the Gaia catalogue.

The other papers in this series

Estimating distances from parallaxes: a tutorial. 2015.
C.A.L. Bailer-Jones
Publications of the Astronomical Society of the Pacific, 127, 994
[abstract] [PDF] [ADS] [arXiv] [journal link]

Estimating distances from parallaxes II. Performance of Bayesian distance estimators on a Gaia-like catalogue. 2016.
T. Astraatmadja, C.A.L. Bailer-Jones
Astrophysical Journal 832, 137
[ADS] [journal] [arXiv]

Estimating distances from parallaxes III. Distances of two million stars in the Gaia DR1 catalogue. 2016.
T. Astraatmadja, C.A.L. Bailer-Jones
Astrophysical Journal, 833, 119
[abstract, paper, and catalogue] [ADS] [arXiv] [journal link]

Estimating distances from parallaxes. IV. Distances to 1.33 billion stars in Gaia data release 2. 2018.
C.A.L. Bailer-Jones, J. Rybizki, M. Fouesneau, G. Mantelet, R. Andrae
Astronomical Journal, 156, 58 (2018)
[abstract, paper, and catalogue] [PDF] [ADS] [arXiv] [journal]

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Last modified: 16 March 2021