HD 4747 [SEP] constellation
HD 4747
HD 4747 is a star that lies approximately 61 light-years away in the constellation of Cetus. The star is a low-amplitude spectroscopic binary, with the secondary being a directly detected brown dwarf.
Binarity.
The binarity of HD 4747 was announced in 2002, based on observations with the HIRES spectrograph at the W. M. Keck Observatory. The radial velocity variation caused by the companion was found to have a semi-amplitude of approximately 0.65 km/s, which evaded detection by earlier spectrographs
due to their precision being poorer than about 1 km/s, but was easily detectable by the 3 m/s precision of HIRES. With a period of 6832 ± 653 days (the large error due to the orbit being unclosed over 1731 day span of observations) and an eccentricity of 0.64 ± 0.06, assuming a primary mass of led to a minimum secondary mass of - well within the brown dwarf regime. HD 4747 B became one of the few brown dwarf candidates orbiting within a few AU of any