AbstractWe are investigating if the orbital geometry of exoplanets affects the activity of their host star by studying 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 (Krejcova 2012, Shkolnik 2013, Kashyap 2008, Poppenhaeger 2010), it is not yet clear whether this activity is driven by magnetic or tidal interactions. We are probing the dependence of star-planet interactions (SPI) on the orbital geometry of the planetary systems by analyzing chromospheric lines (such as Ca II H & K) for variability phased with the exoplanet's orbit. We have obtained high resolution spectra of several systems with the McDonald 2.1-m Sandiford echelle spectrograph, ARCES on the APO 3.5-m, and for HIRES on Keck I from the Keck Observatory Archive. We describe our methodology and review how our results will use orbital geometry to deduce how planets may affect the activity of their host stars.