Long, accurate time series measurements of radial velocities of solar-type stars

Abstract

We have been measuring changes in the radial velocities (RV’s) of solar-type stars to search for gravitational perturbations by planets. We transmit violet starlight through a Fabry-Perot etalon interferometer and sense changes in Doppler shift from changes in the fluxes of light on the slopes of stellar absorption lines. Our data now span 6 years. Our observations of the Sun showed earlier that both our technique and the profiles of solar photospheric violet absorption lines can be stable enough to reveal planetary perturbations. We now carry this validation to the spectra of other near-solar-type stars. Annual averages of our RV’s of σ Draconis and β Virginis are stable to ±6 m s-1. The slope of our five-year series of RV’s of ξ Bootis A is consistent with the star’s well-determined visual astrometric orbit about ξ Bootis B. The Fabry-Perot technique of Doppler shift measurement is fully capable of detecting perturbations due to planets with masses and orbits similar to those of Jupiter.