Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

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. Koposov, G. G. Sacco, S. Randich, G. Gilmore, M. Asplund, J. Binney, P. Bonifacio, J. E. Drew, S. Feltzing, A. Ferguson, G. Micela, I. Negueruela, T. Prusti, H.-W. Rix, A. Vallenari, E. J. Alfaro, C. A. Prieto, C. 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. A. 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. Worley, S. Zaggia

Abstract

Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very Large Telescope.
Aims. A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (vsini) for representative samples of Galactic stars, which will complement information obtained by the Gaia astrometry satellite.
Methods.
We present an analysis to empirically quantify the size and distribution of uncertainties in RV and vsini using spectra from repeated exposures of the same stars.
Results. We show that the uncertainties vary as simple scaling functions of signal-to-noise ratio (S/N) and vsini, that the uncertainties 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 are better represented by Student’s t-distributions than by normal distributions.
Conclusions. Parametrised results are provided, which enable estimates of the RV precision for almost all GES measurements, and estimates of the vsini precision for stars in young clusters, as a function of S/N, vsini and stellar temperature. The precision of individual high S/N GES RV measurements is 0.22–0.26 km s-1, dependent on instrumental configuration.

Keywords
stars: kinematics and dynamics – open clusters and associations: general

Astronomy and Astrophysics
Volume 580, Page A75
August 2015

>> PDF>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website