Peering through the dust: Precise astrometry of the Galactic mid-plane with the VVV survey

Leigh Smith, Philip Lucas, Hugh Jones (University of Herfordshire, UK)

Gaia will see little of the Galactic mid-plane and nuclear bulge due to high extinction at optical wavelengths. To study the structure and kinematics of the inner Galaxy we must look at longer wavelengths. The Vista Variables in the Via Lactea (VVV) survey currently provides just over 4 years of observations covering approximately 560 square degrees of the Galactic bulge and plane. Typically each source is observed 50-150 times in the Ks band over this period. Using these data we provide relative proper motions for approximately 200 million unique sources down to Ks~16 with uncertainties approaching 1mas/yr. In addition, we fit a solution of the parallactic motion of all sources with significant proper motion. These results will allow us to identify faint common proper motion companions to Gaia's discoveries, increasing the number of low mass benchmark objects. We describe how the Gaia absolute astrometric reference grid will allow us anchor our results and measure the streaming motions of stars in the bulge. Finally, we illustrate how the catalogue can be used to kinematically investigate the nature of the numerous optically invisible high amplitude variable stars that VVV is discovering.

Topic revision: r1 - 2014-11-28 - SusanaBascon
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