HD 128311 c

HD 128311 c is an exoplanet located approximately 54 light-years away in the constellation of Boötes. This planet orbits in an eccentric orbit at 1.74 AU from its star (HD 128311). The planet has a minimum mass of 3.22 M_J,^[2] and astrometric observations in 2014 revealed its true mass to be 3.789 M_J.^[1]

HD 128311 c

Discovery
Discovered by	Vogt et al.
Discovery site	California, United States
Discovery date	June 24, 2005
Detection method	Doppler spectroscopy
Orbital characteristics[1]
Apastron	2.02 AU (302,000,000 km)
Periastron	1.46 AU (218,000,000 km)
Semi-major axis	1.740 ± 0.010 AU (260,300,000 ± 1,500,000 km)
Eccentricity	0.159±0.006
Orbital period (sidereal)	921.538 ± 1.15 d (2.52303 ± 0.00315 a)
Average orbital speed	20.7
Inclination	55.950±14.553
Longitude of ascending node	229.392±14.473
Time of periastron	2449565.615±18.01
Argument of periastron	15.445±6.87
Semi-amplitude	74.799±1.497
Star	HD 128311
Physical characteristics[1]
Mass	3.789+0.924 −0.432 MJ