The Gaia-ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities

R. J. Jackson, R. D. Jeffries, J. Lewis, S. E. Koposov, G. G. Sacco, S. Randich, G. Gilmore, M. Asplund, J. Binney, P. Bonifacio, J. E. Drew, S. Feltzing, A. M. N. Ferguson, G. Micela, I. Neguerela, T. Prusti, H.-W. Rix, A. Vallenari, E. J. Alfaro, C. Allende PrietoC. Babusiaux, T. Bensby, R. Blomme, A. Bragaglia, E. Flaccomio, P. Francois, N. Hambly, M. Irwin, A. J. Korn, A. C. Lanzafame, E. Pancino, A. Recio-Blanco, R. Smiljanic, S. Van Eck, N. Walton, A. Bayo, M. Bergemann, G. Carraro, M. T. Costado, F. Damiani, B. Edvardsson, E. Franciosini, A. Frasca, U. Heiter, V. Hill, A. Hourihane, P. Jofré, C. Lardo, P. de Laverny, K. Lind, L. Magrini, G. Marconi, C. Martayan, T. Masseron, L. Monaco, L. Morbidelli, L. Prisinzano, L. Sbordone, S. G. Sousa, C. C. Worley, S. Zaggia

Research output: Contribution to journalArticlepeer-review


Context. The Gaia-ESO Survey (GES) is a large public spectroscopicsurvey at the European Southern Observatory Very Large Telescope. Aims: A key aim is to provide precise radial velocities (RVs) andprojected equatorial velocities (vsini) for representative samples ofGalactic stars, which will complement information obtained by the Gaiaastrometry satellite. Methods: We present an analysis toempirically quantify the size and distribution of uncertainties in RVand vsini using spectra from repeated exposures of the same stars. Results: We show that the uncertainties vary as simple scalingfunctions of signal-to-noise ratio (S/N) and vsini, that theuncertainties become larger with increasing photospheric temperature,but that the dependence on stellar gravity, metallicity and age is weak.The underlying uncertainty distributions have extended tails that arebetter represented by Student's t-distributions than by normaldistributions. Conclusions: Parametrised results are provided,which enable estimates of the RV precision for almost all GESmeasurements, and estimates of the vsini precision for stars in youngclusters, as a function of S/N, vsini and stellar temperature. Theprecision of individual high S/N GES RV measurements is 0.22-0.26 kms-1, dependent on instrumental configuration.
Original languageEnglish
JournalAstronomy & Astrophysics
Publication statusPublished - 5 Aug 2015


  • stars: kinematics and dynamics
  • open clusters and associations: general


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