Multiple Companions to HD 154857 and HD 160691

Abstract

Precise Doppler measurements from the Anglo-Australian Telescope (AAT) UCLES spectrometer reveal two companions to both HD 154857 and HD 160691. The inner companion to HD154857 has a period of 398 days, an eccentricity of 0.51, and aminimum mass of 1.8MJ. An outer companion has a periodmuch longer than 2 yr and is currently detected only as a linear trend of 14 m s?1 yr?1. The inner companion to HD 160691, previously announced from AAT data, has a period of 645 days, an eccentricity of 0.20, and a minimum mass of 1.7MJ.For the outer planet,whose orbit is lesswell constrained, a two-Keplerian fit yields a period of 8.2 yr, an eccentricity of 0.57, and a minimum mass of 3.1MJ.With these orbital parameters, its maximum separation from the star of 0B4 makes it a viable target for direct imaging. Subject