GAIA accuracy on radial velocities assessed from a synthetic spectra database

Abstract

Spectrograph aboard the GAIA satellite operates in the near-IR, in the 8490-- 8740 Åwindow accessible also from the ground. The most important parameter yet to be determined is the spectral resolution. Realistic estimates of the zodiacal light background are obtained and a total of $2\times 10^5$ correlation runs are used to study the accuracy of radial velocity measured by the spectrograph as a function of resolution, magnitude of the target, its spectral type and luminosity class. Accuracy better than 2 km/s is achievable for bright stars if a high enough dispersion is chosen. Radial velocity error of 5 km/s is at $V=17.5$ for Cepheids and at 17.7 for horizontal branch stars. Even for very faint objects, with spectra dominated by background and readout noise, the optimal dispersion is still in the 0.25 / 0.75 Å/pix range. This is also true for complicated cases such as spectroscopic binaries or if information other than radial velocity, i.e. abundances of individual elements or stellar rotation velocity, is sought after. The results can be scaled to assess performance of future ground based instruments.

accepted for publication in Astronomy and Astrophysics, 8 pages, 4 figures

References in corpus (3)

• GAIA: Composition, Formation and Evolution of the Galaxy
• Evaluating GAIA performances on eclipsing binaries. I. Orbits and stellar parameters for V505 Per, V570 Per and OO Peg
• On the accuracy of GAIA radial velocities

Cited by in corpus (6)

• The Radial Velocity Experiment (RAVE): first data release
• The RAdial Velocity Experiment (RAVE): Fourth data release
• The Radial Velocity Experiment (RAVE): second data release
• Spectroscopic survey of the Galaxy with Gaia I. Design and performance of the Radial Velocity Spectrometer
• An extensive library of synthetic spectra covering the far red, RAVE and GAIA wavelength ranges
• The Gaia Spectroscopic Instrument (RVS): A Technical Challenge