The GAPS Programme with HARPS-N@TNG V. A comprehensive analysis of the XO-2 stellar and planetary systems

摘要: XO-2 is the first confirmed wide stellar binary system where almost twin components XO-2N and XO-2S have planets. This stimulated a detailed characterization study of planetary based on new observations. We collected high-resolution spectra with HARPS-N spectrograph multi-band light curves. Spectral analysis led to an accurate determination atmospheric parameters activity. 14 transit curves XO-2Nb used improve parameters. Photometry provided magnitude differences between stars measure their rotation periods. The iron abundance was found be +0.054 dex greater, within more than 3-sigma, that XO-2S. confirm long-term variation in radial velocities XO-2N, we detected turn-over respect previous measurements. suggest presence second massive companion outer orbit or activity cycle as possible causes observed acceleration. latter explanation seems plausible present dataset. obtained value projected spin-orbit angle for (lambda=7+/-11 degrees), estimated real 3-D (psi=27 +12/-27 degrees). measured periods, P=41.6 days case excellent agreement predictions. period appears shorter, ambiguity 26 34.5 cannot solve dataset alone. active companion, this could due fact sampled different phases cycle, interaction its hot Jupiter not confirm.