J/ApJ/833/119 Distances of Gaia DR1 TGAS sources (Astraatmadja+, 2016)
Estimating distances from parallaxes.
III. Distances of two million stars in the Gaia DR1 catalogue.
Astraatmadja T.L., Bailer-Jones C.A.L.
<Astrophys. J., 833, 119 (2016)>
=2016ApJ...833..119A 2016ApJ...833..119A
ADC_Keywords: Surveys ; Parallaxes, trigonometric ; Stars, distances
Keywords: catalogs - methods: data analysis - methods: statistical -
parallaxes - stars: distances - surveys
Abstract:
We infer distances and their asymmetric uncertainties for two million
stars using the parallaxes published in the Gaia DR1 (GDR1) catalogue.
We do this with two distance priors: A minimalist, isotropic prior
assuming an exponentially decreasing space density with increasing
distance, and an anisotropic prior derived from the observability of
stars in a Milky Way model. We validate our results by comparing our
distance estimates for 105 Cepheids which have more precise,
independently estimated distances. For this sample we find that the
Milky Way prior performs better (the RMS of the scaled residuals is
0.40) than the exponentially decreasing space density prior (RMS is
0.57), although for distances beyond 2kpc the Milky Way prior performs
worse, with a bias in the scaled residuals of -0.36 (vs. -0.07 for the
exponentially decreasing space density prior). We do not attempt to
include the photometric data in GDR1 due to the lack of reliable
colour information. Our distance catalogue is available at
http://www.mpia.de/homes/calj/tgas_distances/main.html. These should
only be used to give individual distances. Combining data or testing
models should be done with the original parallaxes, and attention paid
to correlated and systematic uncertainties.
Description:
This is a catalogue of distances and their asymmetric uncertainties
inferred from the parallaxes published in the Gaia DR1 catalogue. Two
priors are used: The exponentially decreasing space density and the
Milky Way prior. For the exponentially decreasing space density prior,
two scale lengths are used: 110pc and 1350pc. The former is based on a
fitting of the true distance distribution of a subset of the GUMS
catalogue (Robin et al., 2012, Cat. VI/137) which are limited to V<11.
This is the magnitude at which Tycho-2 is 99% complete. The latter is
based on the same procedure but limited to G=20.7, which is the
expected limiting magnitude of Gaia. For the Milky Way prior, the
parameters are described in the paper.
We report the mode of the posterior PDF, the median, the 90% credible
interval, and a standard deviation in distance which are calculated by
scaling the 90% into 68.3%.
The Cepheids data used for the validation of the results are included
here as well. They are taken from Groenewegen (2013, Cat.
J/A+A/550/A70) and cross-matched with Hipparcos and/or Tycho by making
a Simbad query of each Cepheids and finding the corresponding
Hipparcos and/or Tyho identifier.
The distances are inferred either by neglecting the systematic
uncertainties of 0.3mas (Gaia Collaboration et al., 2016, Cat. I/337)
for reasons described in the paper, or by adding a systematic
uncertainties of 0.3mas in quadrature with the random parallax
uncertainties. We provide both results here.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
distall.dat 359 2057050 Distances and uncertainties of all TGAS sources,
no systematics uncertainties included
(tgasdistall_v01)
distallw.dat 359 2057050 Distances and uncertainties of all TGAS sources,
systematics uncertainties of 0.3mas included
(tgasdistallwithsysv01.csv)
distcep.dat 400 105 Distances and uncertainties of all TGAS sources
containing Groenewenegen (2013, J/A+A/550/A70)
Cepheids, no systematics uncertainties included
(tgasdistcepheids_v01.csv)
distcepw.dat 400 105 Distances and uncertainties of all TGAS sources
containing Groenewenegen (2013, J/A+A/550/A70)
Cepheids, systematics uncertainties of 0.3mas
included (tgasdistcepheidswithsysv01.csv)
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/A+A/550/A70 : Galactic & Magellanic Clouds Cepheids distances
(Groenewegen 2013)
Byte-by-byte Description of file: distall.dat distallw.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HIP ? Hipparcos identifier
8- 19 A12 --- Tycho2 Tycho 2 identifier
21- 39 I19 --- Source Gaia (I/337) source ID
41- 58 F18.14 deg GLON Galactic longitude at epoch J2015.0
60- 77 F18.14 deg GLAT Galactic latitude at epoch J2015.0
79- 96 F18.14 mas varpi Absolute barycentric stellar parallax of the
source at epoch 2015.0
98-113 F16.14 mas e_varpi Standard error of parallax
115-120 F6.3 mag <Gmag> G-band mean magnitude
122-135 F14.9 pc rMoExp1 Mode distance of the posterior, using the
exponentially decreasing space density prior
with L=0.11kpc
137-151 F15.9 pc r5Exp1 5th percentile of the posterior, using the
exponentially decreasing space density prior
with L=0.11kpc
153-167 F15.9 pc r50Exp1 50th percentile (i.e. the median) of the
posterior, using the exponentially decreasing
space density prior with L=0.11kpc
169-183 F15.9 pc r95Exp1 95th percentile of the posterior, using the
exponentially decreasing space density prior
with L=0.11kpc
185-197 F13.9 pc sigmaRExp1 Distance standard error, using the
exponentially decreasing space density prior
with L=0.11kpc
199-213 F15.9 pc rMoExp2 Mode distance of the posterior, using the
exponentially decreasing space density prior
with L=1.35kpc
215-229 F15.9 pc r5Exp2 5th percentile of the posterior, using the
exponentially decreasing space density prior
with L=1.35kpc
231-245 F15.9 pc r50Exp2 50th percentile (i.e. the median) of the
posterior, using the exponentially decreasing
space density prior with L=1.35kpc
247-261 F15.9 pc r95Exp2 95th percentile of the posterior, using the
exponentially decreasing space density prior
with L=1.35kpc
263-276 F14.9 pc sigmaRExp2 Distance standard error, using the
exponentially decreasing space density prior
with L=1.35kpc
278-292 F15.9 pc rMoMW Mode distance of the posterior,
using Milky Way Prior
294-309 F16.9 pc r5MW 5th percentile of the posterior,
using Milky Way Prior
311-326 F16.9 pc r50MW 50th percentile (i.e. the median) of the
posterior, using Milky Way Prior
328-343 F16.9 pc r95MW 95th percentile of the posterior,
using Milky Way Prior
345-359 F15.9 pc sigmaRMW Distance standard error, using Milky Way Prior
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Byte-by-byte Description of file: distcep.dat distcepw.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- HIP ? Hipparcos identifier
8- 18 A11 --- Tycho2 Tycho 2 identifier
20- 38 I19 --- Source Gaia (I/337) source ID
40- 57 F18.14 deg GLON Galactic longitude at epoch J2015.0
59- 76 F18.14 deg GLAT Galactic latitude at epoch J2015.0
78- 94 F17.14 mas varpi Absolute barycentric stellar parallax of the
source at epoch 2015.0
96-111 F16.14 mas e_varpi Standard error of parallax
113-118 F6.3 mag <Gmag> G-band mean magnitude
120-133 F14.9 pc rMoExp1 Mode distance of the posterior, using the
exponentially decreasing space density prior
with L=0.11kpc
135-147 F13.9 pc r5Exp1 5th percentile of the posterior, using the
exponentially decreasing space density prior
with L=0.11kpc
149-162 F14.9 pc r50Exp1 50th percentile (i.e. the median) of the
posterior, using the exponentially decreasing
space density prior with L=0.11kpc
164-177 F14.9 pc r95Exp1 95th percentile of the posterior, using the
exponentially decreasing space density prior
with L=0.11kpc
179-191 F13.9 pc sigmaRExp1 Distance standard error, using the
exponentially decreasing space density prior
with L=0.11kpc
193-206 F14.9 pc rMoExp2 Mode distance of the posterior, using the
exponentially decreasing space density prior
with L=1.35kpc
208-221 F14.9 pc r5Exp2 5th percentile of the posterior, using the
exponentially decreasing space density prior
with L=1.35kpc
223-236 F14.9 pc r50Exp2 50th percentile (i.e. the median) of the
posterior, using the exponentially decreasing
space density prior with L=1.35kpc
238-251 F14.9 pc r95Exp2 95th percentile of the posterior, using the
exponentially decreasing space density prior
with L=1.35kpc
253-266 F14.9 pc sigmaRExp2 Distance standard error, using the
exponentially decreasing space density prior
with L=1.35kpc
268-281 F14.9 pc rMoMW Mode distance of the posterior, using
Milky Way Prior
283-296 F14.9 pc r5MW 5th percentile of the posterior, using
Milky Way Prior
298-311 F14.9 pc r50MW 50th percentile (i.e. the median) of the
posterior, using Milky Way Prior
313-326 F14.9 pc r95MW 95th percentile of the posterior, using
Milky Way Prior
328-341 F14.9 pc sigmaRMW Distance standard error, using Milky Way Prior
343-351 A9 --- CepName Cepheid name
353-362 A10 --- HIPName Hipparcos identifier (HIP NNNNNN)
364-378 A15 --- TYC Tycho 2 identifier (TYC NNNN-NNNN-N)
380-386 F7.1 pc rCep Cepheid distance
388-393 F6.1 pc sigmaRCep1 Error in the fit on rCep
395-400 F6.1 pc sigmaRCep2 Error based on Monte-Carlo simulation on rCep
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Acknowledgements:
Tri L. Astraatmadja, tastraatmadja(at)carnegiescience.edu
DTM, Carnegie Institution for Science
References:
Bailer-Jones, Paper I, 2015PASP..127..994B 2015PASP..127..994B
Astraatmadja & Bailer-Jones, Paper II 2016ApJ...832..137A 2016ApJ...832..137A
(End) Tri L. Astraatmadja [DTM, CIS], Patricia Vannier [CDS] 29-Sep-2016