5 Galactic GC proper motions from Gaia DR1 Virtual Observatory Resource

Authors
  1. Watkins L.L.
  2. van der Marel R.P.
  3. Published by
    CDS
Abstract

We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho-Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneous PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope (HST) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST. By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories.

Keywords
  1. globular-star-clusters
  2. visible-astronomy
  3. trigonometric-parallax
  4. proper-motions
  5. radial-velocity
Bibliographic source Bibcode
2017ApJ...839...89W
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/839/89
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJ/839/89
Document Object Identifer DOI
doi:10.26093/cds/vizier.18390089

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History

2018-01-12T10:55:34Z
Resource record created
2018-01-12T10:55:34Z
Created
2019-04-08T12:59:15Z
Updated

Contact

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CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
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cds-question@unistra.fr