Radial velocity comparison of Gaia DR2 and RAVE DR5 survey: a systematic offset in radial velocities among a group of highly accurate radial velocity stars

Abstract

Here, we report comparative study of radial velocity ($\mathrm{RV}$) data of two major surveys: Gaia Data Release 2 and RAVE Data Release 5. We restricted the sample to stars with relatively accurate radial velocities (${\sigma }_{\mathrm{R}{\mathrm{V}}_{\mathrm{Gaia}}}\le$ 2 km s${}^{-1}$ or $\le$ 2%, and ${\sigma }_{\mathrm{R}{\mathrm{V}}_{\mathrm{RAVE}}}\le$ 2 km s${}^{-1}$ or $\le$ 2%). The difference between $\mathrm{R}{\mathrm{V}}_{\mathrm{Gaia}}$ and $\mathrm{R}{\mathrm{V}}_{\mathrm{RAVE}}$ for a majority of the sample follows normal distribution with mean = 0.28 km s${}^{-1}$ and $\sigma$ = 1.49 km s${}^{-1}$. However, we found a very small group of stars ($\approx 0.08\%$ of the total) for which the difference in radial velocities between the two surveys is significantly larger with an offset of $-$104.50 km s${}^{-1}$ with $\sigma$ = 4.92 km s${}^{-1}$. Kinematics based on $\mathrm{R}{\mathrm{V}}_{\mathrm{Gaia}}$ suggest that most of the group members belong to the Galactic thin disk which agrees with the group's metallicity range of $-$1.2 to $+$0.5 dex suggesting the offset in radial velocity is probably due to RAVE velocity data for this particular group.

7 pages, 6 figures, accepted for publication in the Astronomical Journal on July 25, 2018

References in corpus (5)

• The Gaia mission
• The Radial Velocity Experiment (RAVE): first data release
• The Radial Velocity Experiment (RAVE): Fifth Data Release
• Gaia broad band photometry
• APASS Landolt-Sloan BVgri photometry of RAVE stars. I. Data, effective temperatures and reddenings

Cited by in corpus (4)

• APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South
• Gaia Data Release 3: Mapping the asymmetric disc of the Milky Way
• Survey of Surveys I: The largest catalogue of radial velocities for the Galaxy
• Gaia Early Data Release 3: Updated radial velocities from Gaia DR2