Speaker: Antoine Strugarek (CEA Paris-Saclay, France)

Title: Star-planet magnetic interaction: recent discoveries and challenges ahead

Abstract: Over the last two decades, a large population of close-in planets has been detected around a wide variety of host stars. These planets are thought to strongly interact with their host stars through intense irradiation, tidal forces, and interactions with the magnetized stellar atmosphere and wind in which they orbit. Can we leverage these interactions to better constrain the properties of both the planets and their host stars? In particular, can we use them to probe planetary magnetic fields?
In this talk, I will report on recent progress made through the ongoing ExoMagnets ERC project at CEA Paris-Saclay. I will first review the observational evidence for star-planet magnetic interactions (SPMI) and present a new, unambiguous detection in the HD 189733 system, as well recent attempts in detecting such signal in radio. I will then present new modeling efforts designed to capture the complex connectivity and energetics of these interactions.
The classical interpretation of SPMI attributes stellar chromospheric hotspots to wave-driven energy deposition. I will present detailed modeling of how this process unfolds and what it implies for stellar activity tracers. However, the observed high emission levels challenge this classical scenario. Drawing a parallel to Comet Lovejoy in the solar system, I will show that SPMI may instead act as a trigger for pre-existing stellar active regions.
Finally, I will discuss the impact of SPMIs on the exoplanets themselves. Specifically, these interactions can induce significant Ohmic heating in upper atmospheres, altering temperature profiles and atmospheric escape rates. I will conclude by introducing astroSPI, an upcoming open-source tool designed to model SPMI properties for specific systems using state-of-the-art constraints on key planetary and stellar parameters.

Note: Hosts: Ilaria Civale and Katja Poppenhäger

• Date:
  Oct. 15, 2026, 2:30 p.m. – 3:30 p.m.
  
  
• Location:

  AIP; Kirch building, Conference room

  
  
• Contact:
  Julián Alvarado-Gómez
  julian.alvarado-gomez@aip.de