Estimating distances from parallaxes. VI.
A method for inferring distances and transverse velocities from parallaxes and proper motions
demonstrated on Gaia Data Release 3
C.A.L. Bailer-Jones
The accuracy of stellar distances inferred purely from parallaxes degrades rapidly with distance. Proper motion measurements, when combined with some idea of typical velocities, provide independent information on stellar distances. Here I build a direction- and distance-dependent model of the distribution of stellar velocities in the Galaxy, then use this together with parallaxes and proper motions to infer kinegeometric distances and transverse velocities for stars in Gaia DR3. Using noisy simulations I assess the performance of the method and compare its accuracy to purely parallax-based (geometric) distances. Over the whole Gaia catalogue, kinegeometric distances are on average 1.25 times more accurate than geometric ones. This average masks a large variation in the relative performance, however. Kinegeometric distances are considerably better than geometric ones beyond several kpc, for example. On average, kinegeometric distances can be measured to an accuracy of 19% and velocities (sqrt[vra^2 + vdec^2]) to 16 km/s (median absolute deviations). In Gaia DR3, kinegeometric distances are smaller than geometric ones on average for distant stars, but the pattern is more complex in the bulge and disk. With the much more accurate proper motions expected in Gaia DR5, a further improvement in the distance accuracy by a factor of (only) 1.35 on average is predicted (with kinegeometric distances still 1.25 times more accurate than geometric ones). The improvement from proper motions is limited by the width of the velocity prior, in a way that the improvement from better parallaxes is not limited by the width of the distance prior.
- Article: Astronomical Journal, 166, 269
[PDF] [arXiv] [ADS] [journal link] - [Plots and data for the velocity prior for each HEALpixel]
- [Description of an alternative implementation that uses only one-dimensional sampling]
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]
Estimating distances from
parallaxes. V. Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3. 2021.
C.A.L. Bailer-Jones, J. Rybizki, M. Fouesneau, M. Demleitner, R. Andrae
Astromomical Journal, 161, 147
[abstract, paper, FAQ, and catalogue
access]
[PDF]
[ADS]
[arXiv]
[journal]
[summary presentation]
[poster]