Radial Velocity Information in Sour-Type Spectra

Abstract

Recent advances in instrumentation and technique have provided hope that changes in stellar radial velocities can be measured with an accuracy of 10 m/s. This tremendous increase in the precision of radial velocity measurements should yield a wealth of new information from studies of stellar oscillations and surface phenomena, as well as offer clues to help answer perhaps the most exciting question, that of the existence of extra-solar planetary systems. The stringent requirements of light scrambling, high signal-to-noise ratio, and the need for frequent or simultaneous calibration (Griffin and Griffin 1973; Serkowski 1978) mean that these new techniques are inherently inefficient. This has limited studies to bright stars and to the use of large telescopes. Without a priori knowledge of the inclination of the rotation axes of the stars under study, searches for planetary systems will require a relatively large number of stars to statistically determine the probability that any of these stars harbor planets. Therefore, it is necessary to extend the limits for precise radial velocity studies to 5th or 6th blue/visual magnitude. Efficient extraction of radial velocity information from the spectrum is essential. Furthermore, attempts to increase limiting precision or decrease limiting magnitudes using conventional techniques will also benefit from increased efficiency.