Alpha and Proxima Centauri

Abstract

The most recent epoch in a previous study by Gasteyer of the distances and motions of Alpha and Proxima was 1951. The present article includes all the observations up to 1971. Old and new material were measured and reduced in a uniform manner, while more comparison stars were used than in the past. The results for the trigonometric parallaxes and the proper motions are tabulated. The new mass ratio, B/(A+B) = 0.454 + or - 0.002, is a substantial improvement on the current value. The new observations are consistent with a common space motion for Alpha and Proxima Centauri. The orbital motion of Proxima around Alpha is not negligible, yet is immeasurably small. No perturbations due to additional low-mass companions have been found. The new masses for Alpha Centauri A and B are 1.10 and 0.91 solar masses, respectively.