This paper presents the simultaneous Bayesian analysis of the radial velocity and activity indices for the K5Ve active star BD+20 1790, that was proposed to host a close-in massive planet by Hernan-Obispo et al. (2010). The Bayesian analysis supports
the hypothesis of a planetary companion. We present a new orbital solution after removing the two main contributions to the stellar jitter, one that varies with the photometric period and another that varies with the synodic period of the star+planet system. We use a new method to determine these jitter components, considering them as a second and third signals in the system. A discussion on possible magnetic star-planet-interaction is included, based on the Bayesian analysis of the activity indices. We propose two possible sources for flare events of this star: one related to the geometry of the system and the relative movement of the star+planet, and a second one purely stochastic source that is related to the evolution of stellar active regions. Also, we observe for the first time the magnetic field of the star, from spectropolarimetric data.
We report the detection of two new planets from the Anglo-Australian Planet Search. These planets orbit two stars each previously known to host one planet. The new planet orbiting HD 142 has a period of 6005pm427 days, and a minimum mass of 5.3M_Jup.
HD142c is thus a new Jupiter analog: a gas-giant planet with a long period and low eccentricity (e = 0.21 pm 0.07). The second planet in the HD 159868 system has a period of 352.3pm1.3 days, and m sin i=0.73pm0.05 M_Jup. In both of these systems, including the additional planets in the fitting process significantly reduced the eccentricity of the original planet. These systems are thus examples of how multiple-planet systems can masquerade as moderately eccentric single-planet systems.
