HD 167665 is a yellow-white huedstar with a brown dwarf companion in the southernconstellation ofSagittarius. With anapparent visual magnitude of 6.39,[2] it is near the lower brightness limit for stars that are visible to the naked eye. Based upon an annualparallax shift of 32.4 mas as seen from Earth, it is located 101 light years from theSun. The star is moving away from the Sun with aradial velocity of +8 km/s.[9]
Based upon regular variations inradial velocity observed between 1996 and 2006, an orbiting companion was announced by theCalifornia and Carnegie Planet Search (CCPS) program in 2007. Thisperturbing object, designated HD 167665 b,[10] has anorbital period of twelve years with aneccentricity of 0.342. Thesemimajor axis of this orbit is 5.62 AU[5] and the object has a mass of at least50.3±0.4 MJ. Since theinclination of the orbit was initially unknown, the exact mass could not be determined, with a 79% chance that the mass of the object constrains it to be abrown dwarf with a mass less than82 MJ.[11] In 2022,astrometric observations confirmed this object to be a brown dwarf, with a true mass of52.708+5.112 −4.403MJ. Its inclination suggests a non-zero probability that ittransits its star.[5]
^abBalachandran, Suchitra (May 1, 1990), "Lithium depletion and rotation in main-sequence stars",Astrophysical Journal, Part 1,354:310–332,Bibcode:1990ApJ...354..310B,doi:10.1086/168691.
^Reffert, S.; Quirrenbach, A. (March 2011), "Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs",Astronomy & Astrophysics,527: 22,arXiv:1101.2227,Bibcode:2011A&A...527A.140R,doi:10.1051/0004-6361/201015861,S2CID54986291, A140.
