I/352 Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
Estimating distances from parallaxes.
V: Geometric and photogeometric distances to 1.47 billion stars in
Gaia Early Data Release 3.
Bailer-Jones C.A.L., Rybizki J., Fouesneau M., Demleitner M., Andrae R .
<Astron. J. 161, 147 (2021)>
=2021AJ....161..147B 2021AJ....161..147B
=2021yCat.1352....0B 2021yCat.1352....0B
ADC_Keywords: Surveys ; Stars, distances
Keywords: catalogs - Galaxy: structure - methods: statistical -
stars: distances - parallax
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. 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 rst, 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
(5log10r-5). The catalogue 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 catalogue.
Description:
We have produced a catalogue of geometric distances for 1.47 billion
stars and photogeometric distances for 92% of these. These estimates,
and their uncertainties, can also be used as estimates of the distance
modulus. Geometric distances use only the EDR3 parallaxes.
Photogeometric distances additionally use the G magnitude and BP-RP
colour from EDR3. Both types of estimate involve directiondependent
priors constructed from a sophisticated model of the 3D distribution,
colours, and magnitudes of stars in the Galaxy as seen by Gaia, i.e.
accommodating both interstellar extinction and a Gaia selection
function. Tests on mock data, but moreover validation against
independent estimates and open clusters, suggest our estimates are
reliable out to several kpc. For faint or more distant stars the prior
will often dominate the estimates.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
gedr3dis.sam 147 1000 Estimating distances from parallaxes
(1467744818 sources)
--------------------------------------------------------------------------------
See also:
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: gedr3dis.sam
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Source Source identifier, identical to the
Gaia-EDR3 source_id (id)
21- 35 F15.11 deg RAdeg Barycentric right ascension (ICRS)
at Ep=2016.0 (ra)
37- 51 F15.11 deg DEdeg Barycentric declination (ICRS)
at Ep=2016.0 (dec)
52- 66 F15.8 pc rgeo ? Median of the geometric distance posterior
(rmedgeo)
68- 81 F14.8 pc b_rgeo ? 16th percentile of the geometric distance
posterior (rlogeo)
83- 96 F14.8 pc B_rgeo ? 84th percentile of the geometric distance
posterior (rhigeo)
97-111 F15.8 pc rpgeo ? Median of the photogeometric distance
posterior (rmedphotogeo)
113-126 F14.8 pc b_rpgeo ? 16th percentile of the photogeometric
distance posterior (rlophotogeo)
128-141 F14.8 pc B_rpgeo ? 84th percentile of the photogeometric
distance posterior (rhiphotogeo)
143-147 I5 --- Flag Flag (flag) (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
The flag field in the catalogue is a string of five decimal digits ABBCC.
A : Source magnitude compared to the limit used to make the prior
0 = Source has no G-band magnitude
1 = G ≤ Glim
2 = G > Glim
B : Hartigan dip test for unimodality.
Left digit geometric, right digit photogeometric
0 = unimodal hypothesis okay
1 = possible evidence for multimodality
C : QG models used in prior.
Left digit bluer model, right digit redder model
0 = null (no model)
1 = one-component Gaussian
2 = two-component Gaussian
3 = smoothing spline
There is one special setting:
99 source lacks G and/or BP-RP
--------------------------------------------------------------------------------
History:
Copied at ftp://ftp.mpia.de/pub/calj/gedr3_distances
Acknowledgements:
Coryn Bailer-Jones, calj(at)mpia.de
References:
Bailer-Jones, Paper I 2015PASP..127..994B 2015PASP..127..994B
Astraatmadja & Bailer-jones, Paper II 2016ApJ...832..137A 2016ApJ...832..137A
Astraatmadja & Bailer-jones, Paper III 2016ApJ...833..119A 2016ApJ...833..119A, Cat. J/ApJ/833/119
Bailer-Jones et al., Paper IV 2018AJ....156...58B 2018AJ....156...58B, Cat. I/347
(End) G. Monari, F.-X. Pineau, P. Vannier [CDS] 18-Feb-2021