Radial velocities & activity index for HD107148

We present an independent Doppler validation and dynamical orbital analysis of the two-planet system HD107148, which was recently announced in Rosenthal et al. Our detailed analyses are based on literature HIRES data and newly obtained HARPS and CARMENES radial-velocity (RV) measurements as part of our survey in search for additional planets around single-planet systems. We perform a periodogram analysis of the available HIRES and HARPS precise RVs and stellar activity indicators.

We do not find any apparent correlation between the RV measurements and the stellar activity indicators, thus linking the two strong periodicities to a moderately compact multiplanet system. We carry out orbital fitting analysis by testing various one- and two-planet orbital configurations and studying the posterior probability distribution of the fitted parameters. Our results solidify the existence of a Saturn-mass planet (HD107148b, discovered first) with a period of Pb~77.2days and a second, eccentric (ec~0.4), Neptune-mass exoplanet (HD107148c) with an orbital period of Pc~18.3days.