Stars interact with their planets through gravitation, radiation, and
magnetic fields. I shall focus on the interactions between late-type stars with
an outer convection zone and close-in planets, i.e., with an orbital semimajor
axis smaller than approximately 0.15 AU. I shall review the roles of tides and
magnetic fields considering some key observations and discussing theoretical
scenarios for their interpretation with an emphasis on open questions.Comment: 20 pages, 5 figures, invited talk at the 18th Cambridge Workshop on
Cool Stars, Stellar Systems, and the Sun, Proceedings of Lowell Observatory,
edited by G. van Belle & H. Harri
