Mu Arae
The star has a planetary system with four known extrasolar planets (designated Mu Arae b, c, d and e; later named Quijote, Dulcinea, Rocinante and Sancho, respectively), three of them with masses comparable with that of Jupiter.
[13][14] In July 2014 the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.
[8] According to measurements made by the Gaia astrometric satellite, Mu Arae exhibits a parallax of 64.0853 milliarcseconds as the Earth moves around the Sun.
Asteroseismic analysis of the star reveals it is approximately 10% more massive than the Sun and significantly older, at around 6.34 billion years.
At the time, the parameters of this planet were poorly constrained and it was thought to be in an orbit of around 8.2 years with a high eccentricity.
[23] Later in 2004, a small inner planet designated Mu Arae c was announced with a mass comparable with that of Uranus in a 9-day orbit.
[24] In 2006, two teams, one led by Krzysztof Goździewski and the other by Francesco Pepe independently announced four-planet models for the radial velocity measurements of the star, with a new planet (Mu Arae d) in a near-circular orbit lasting approximately 311 days.
[10][11] The new model gives revised parameters for the previously known planets, with lower eccentricity orbits than in the previous model and including a more robust characterization of the orbit of Mu Arae e. The discovery of the fourth planet made Mu Arae the second known four-planet extrasolar system, after 55 Cancri.
More stable solutions, including ones in which the two planets are actually in the resonance (similar to the situation in the Gliese 876 system) can be found which give only a slightly worse fit to the data.
[28] The gas giant planet "b" is located in the liquid water habitable zone of Mu Arae.
This would prevent an Earth-like planet from forming in the habitable zone, however large moons of the gas giant could potentially support liquid water.
