Spectrographs, Asteroids and Constants

Abstract

Astronomical search for a variation of fundamental constants deals with accurate radial velocity measurements and needs reliable astronomical standards to calibrate the spectrographs to assess possible systematics. We show that the sunlight reflected by Asteroids provide a radial velocity standard of high precision. Preliminary we needed to produce a solar Atlas with a higher precision factor of one order of magnitude, i.e. down to about 10 m s − 1at a specific wavelength. The asteroid-based technique is used here to study radial velocity deviations in UVES as claimed recently. Preliminary results suggest the presence of systematics at the level of ≈ 80 m s − 1, i.e. of ≈ 4 ×10^− 6 in δα ∕ α.