Rho Coronae Borealis

Rho Coronae Borealis is a star similar to the Sun but of greater age, around which has been found a planet marginally more massive than Jupiter. This epistellar Jovian, the fourth of its type to be discovered, occupies a nearly circular, sub-Mercurian orbit around its host.


Host star
Distance 55 light-years (16.7 pc)
Spectral type G0 V or G2 V
Temperature 5,480°C (5,750 K)
Luminosity (Sun = 1) 1.8
Mass (Sun = 1) 0.89
Apparent magnitude 5.4


Mass (Jupiter = 1) 1.13
Semi-major axis 0.25 AU (37.5 million km, 23.3 million mi.)
Orbital period 39.65 days
Eccentricity 0.028
Year of discovery 1997
Discoverer Robert Noyes et al (AFOE)
Method of discovery radial velocity



1. Noyes, R., et al. "A Planet Orbiting the Star Rho Coronae Borealis," Astrophysical Journal, 483, 111 (1997).