Thursday, June 12 - Plenary Session

Name:  Antoine Strugarek

Affiliation:  Université de Montréal

Title:  Close-in Planets and Magnetic Torques: What Impact on Stellar Evolution?

The diversity of masses, sizes and orbits of known exoplanets has prompted recent efforts in the scientific community to explore the broad range of interactions that can exist between planets and their host stars. In particular, planets orbiting inside the stellar wind Alfvén radius can magnetically influence their host star and sometimes influence the angular momentum evolution of the system. Among the numerous star-planet interaction (SPI) models that have been developed, magnetohydrodynamic (MHD) simulations combine state of the art numerical models of cool star magnetospheres with simplified models of planets. The advantage of these global, dynamical models is the ability to assess the effects of SPI on both the planet and host star, in a self-consistent way. We will present our study of global magnetic SPI using the PLUTO code. We first give an overview of different types of interactions, depending on the stellar wind and orbital properties. Planets can magnetically influence host star angular momenta in two ways: (1) via a direct magnetic connection between the star and planet, and (2) by significantly modifying the stellar wind. We explore these mechanisms for cases of both magnetized and unmagnetized planets, in order to characterize the potential influence on the rotational history of the star, as well as the planetary orbital migration. We show that the key factors for the interaction are the relative magnetic field strengths and topologies of the two bodies, as well as the strength of the stellar wind. In some cases, the planet transfers an amount of angular momentum to the star that is comparable to the amount being removed by the wind, which can have a significant impact on the evolution of the star.