HD planetary system Artwork of a view from a moon of the gas giant planet that orbits the primary star of the triple star system HD The primary star A is not seen but the other two stars of HD which form a binary star system called B are seen on the horizon at lower left The existence of this gas giant planet was inferred from gravitational wobbles of the primary star A The discovery was announced in July by Maciej Konacki of Caltech USA The planet orbits its star in days and has a mass at least times that of Jupiter Several gas giant planets have now been discovered orbiting nearby stars