The search for star-planet interactions in eccentric systems

We have undertaken a study to determine if the orbital geometry of exoplanets affects the activity of their host stars by observing a sample of planetary systems known to contain massive planets on short period, highly elliptical orbits. While recent studies in the optical, UV, and X-Ray have shown enhanced chromospheric activity for stars hosting exoplanets with orbital semi-major axes less than 0.1 AU [1, 2, 3, 4], it is not yet clear whether this activity is driven by magnetic or tidal interactions. In this study, we are probing the dependence of star-planet interactions (SPI) on orbital geometry in a selection of eccentric systems by analyzing the Ca II H & K emission lines for variability phased with the planet's orbit. We have obtained high resolution spectra of this systems with the ARCES on the APO 3.5m from the Keck Observatory Archive. We shall describe our methodology and review our results on how the orbital geometry of the planet affects the activity of its host star.References[1] Krejcova, T., & Budaj, J., 2012, A&A, 540, A82[2] Shkolnik, E., 2013, ApJ pre-print from arXiv:1301.6192v1[3] Kashyap, V.L., Drake, J.J., & Saar, S.H., 2008, ApJ, 687, 1339[4] Poppenhaeger, K., Robrade, J., & Schmitt, J.H., 2010, A&A, 515, A98