Estimating Distances from Parallaxes. V. Geometric and Photogeometric Distances to 1.47 Billion Stars in Gaia Early Data Release 3

Abstract

Stellar distances constitute a foundational pillar of astrophysics. The publication of 1.47 billion stellar parallaxes from Gaia is a major contribution to this. 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 with a direction-dependent prior on distance. The second, photogeometric, additionally uses the color and apparent magnitude of a star, by exploiting the fact that stars of a given color 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 catalog 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 ( ). The catalog may be downloaded or queried using ADQL at various sites (see http://www.mpia.de/~calj/gedr3_distances.html), where it can also be cross-matched with the Gaia catalog.

Mapping luminous hot stars in the Galaxy

“…5. Figure 9 (left) shows the comparison between our astrokinematic distances and the photo-geometric distances estimated by Bailer-Jones et al (2020). More than 85% of the sources have astro-kinematic distances consistent within 1σ with the photogeometric distances from Bailer-Jones et al (2020).…”

“…For distances smaller than ∼4 kpc, parallax uncertainties dominate the fractional error distribution. This is a regime where σ / < 0.1, and the inverse parallax is a good distance estimate (see also Bailer-Jones et al 2020). For distances larger than ∼4 kpc, the kinematic model and the other priors described above keep the distance uncertainties from exploding.…”

“…By assuming that young massive stars are on near-circular orbits with a small velocity dispersion, we compute astrokinematic distances, and compare them to those derived by Bailer-Jones et al (2020). We use these distances to study the distribution of sources in the Galactic disc of a subset of the target sample, which we obtain by filtering out sources with spurious astrometric solutions and kinematic properties inconsistent with our model.…”

Multi-wavelength VLTI study of the puffed-up inner rim of a circumbinary disc

“…Notes. (a) The entry 'geometric distance' in the distance catalogue of Bailer-Jones et al ( 2021) was used, except for HD 123139 which is not in Gaia EDR3 and therefore not processed by Bailer-Jones et al (2021). In that case, we used the Hipparcos parallax to estimate the distance.…”

“…Optical interferometric techniques are, thus, needed to probe the compact infrared emission from the inner regions of such discs. In this contribution we present our interferometric multi-wavelength approach for one specific post-AGB binary system: IRAS 08544−4431 (hereafter IRAS 08544), located at an approximate distance of 1.53 ± 0.12 kpc (Bailer-Jones et al 2021). This system has been studied in Hillen et al (2016), in which a successful interferometric imaging experiment is presented with data obtained with PIONIER (H-band) and in Kluska et al (2018), in which a radiative transfer approach was used to explain the inner rim emission in the PIONIER data.…”