A SPECTROSCOPIC ORBIT FOR HR 152.

Abstract

ABSTRACT HR 152, one of the four reference stars used to standardize radial-velocity observations made at Cambridge, has been shown by measurements made with the Dominion Astrophysical Observatory radial-velocity spectrometer to be a spectroscopic binary. The effects of its variability are traceable in the residuals of many spectroscopic-binary orbits based on Cambridge data. The orbit has a period of 576 days and a semiamplitude of 0.69±0.08 km s-1; this is the first plausible orbit to be published with a semiamplitude smaller than 1 km s-1.