Having casting doubt on the existence of 47 Uma c, Wittenmyer et al. (2007) offer a new planetary candidate that would add another two-planet system to the total observed within 20 parsecs. Concurring with suggestions by Gozdziewski et al. (2006) and Wright et al. (2007), Wittenmyer’s group proposes that the K0 star 14 Herculis hosts a second planet exterior to the enormous gas giant previously announced.

The primary star, located at a distance of 18.5 parsecs (59 light years), is similar in mass to Sol (0.99 MSOL according to Butler et al. 2006; 0.90 MSOL according to Wittenmyer’s group) but far richer in heavier elements. Its metallicity of 0.46 makes 14 Herculis the most enhanced planetary host within 40 parsecs. Among nearby stars, only Epsilon Reticuli ([Fe/H] = 0.42) can rival this endowment. The Extrasolar Planets Encyclopaedia suggests an age of about 700 million years, even younger than Epsilon Eridani.

The confirmed planet, 14 Herculis b, is about 5 times as massive as Jupiter, with a semimajor axis of 2.85 AU (or 2.77 AU, according to Wittenmyer’s group) and an orbital period of 4.8 Earth years. Wittenmyer’s group offers only preliminary minimum values for the second planet, 14 Herculis c. Its mass is at least 2.1 MJUP; its semimajor axis is at least 6.9 AU; and its orbital period is at least 19 years. This proposed two-planet system bears a strong resemblance to the revised system architecture that Wittenmyer and colleagues suggest for 47 Uma. Among the principal differences are the lower luminosity of 14 Herculis, implying a correspondingly tighter ice line; and the greater mass and eccentricity of 14 Herculis b (e = 0.37, as opposed to e = 0.06 for 47 Uma b), implying still more prohibitive constraints on any interior orbits.

Data on this page last updated February 2007.