2001MNRAS.325...55S

We present a search for periodicities (P_chr) in the chromospheric Caii infrared triplet emission of several stars (τ Boo, 51 Peg, υ And, ρ¹ Cnc, ρ CrB, 70 Vir and GL 876) which may be directly attributable to interaction with close-in giant planets. Activity enhancements could arise from increased non-radiative heating and dynamo action in planet-induced tidal bulges (with P_chr~P_orb/2), or from interactions between the stellar and planetary magnetic fields (with P_chr~P_orb). We compare both P_chr and the phase dependence of the activity with the planetary orbital period P_orb, the orbital phase, and models. No significant P_chr or phase dependence attributable to planets can be clearly identified. We place approximate upper limits on the amplitude of any planet-induced activity. We identify a possible stellar rotation period for GL 876, and support previous period determinations for four other stars. We discuss the results and possible directions of future research.