Characterization of the magnetism of exoplanets

Introduction

The research in exoplanetary sciences has skyrocketed since the first discovery of planet 51 Peg b by Mayor and Queloz (1995). More than 5200 exoplanets have been discovered since and have revolutionized our understanding of how star-planet systems are formed and evolve. More and more exoplanets keep being discovered today, and their characteristics and that of their host star are being precisely determined using space-based and ground-based multi-wavelength observations.

Current Knowledge Gaps

Nevertheless, we are still blind to a fundamental aspect of exoplanets: what kind of magnetism and magnetosphere do they possess? On Earth, we know the magnetic field shields the atmosphere from the space environment and has been essential to maintaining life as we know it.

Future Prospects

With the advent of the SKA Observatory, we expect to detect magnetospheric radio signals from hundreds of exoplanets. These magnetospheres also lead to star-planet magnetic interactions for about a third of the known exoplanets, which leave observable traces on the activity tracers of the host star. However, such detections are not enough by themselves to quantify the magnetic properties of exoplanets due to an incomplete theoretical understanding of magnetic interactions.

Research Objectives

In ExoMagnets, we will therefore address the following science questions:

1. How do planets interact magnetically with their environments?
2. How much energy can be involved, and what observational tracers can be detected?
3. What type of magnetism can be sustained by an Earth in the habitable zone of a low-mass star?

Methodology

We will address these questions by filling out the present theoretical gaps about the magnetic coupling between an exoplanet and its local environment. We will quantify for the first time its energetics, its observable multi-wavelength spectrum, and leverage them to constrain the magnetism of exoplanets on short-period orbits. These approaches will be combined to provide the theoretical tools to characterize the magnetism of a large sample of exoplanets.