Imprints of Magnetic fields in Exoplanets

ongoing

The fast-growing sample of thousands of extrasolar planets is unveiling an amazing variety of properties. It represents an opportunity to shed light on long-standing physics and astrobiology issues from a much wider sample than our Solar neighbours, especially for what concerns the still unclear internal structure, only grossly constrained by observable values of mass and/or radii. Planetary magnetism and its long-term evolution is currently understood only partially for the Earth, at a lesser extent for Jupiter and other Solar planets, and is still elusive in exoplanets. The project focuses on magnetic fields as a key factor in shaping habitability and as a messenger of the internal composition and dynamics. For terrestrial planets, long-lasting, strong enough magnetic fields are arguably a key factor to guarantee habitability, but we are not even sure about how the Earth’s magnetic field has survived for so long. Magnetism leaves other detectable imprints in giant planets. A quest for the first exoplanetary Jupiter-like magnetospheric emission in radio is on-going, but the search needs to be driven by a reliable prediction of the most likely emitters. Magnetic fields can delay the cooling via Ohmic dissipation and could explain the often observed inflated radii in hot Jupiters, but models are still incomplete. IMAGINE will simulate the long-term (Gyr) evolution of the exoplanetary magnetic fields, coupled with a cooling model, and will assess the relevant imprints on their observables for a broad range of distinctive features mass, composition, irradiation, rotation. Combining a novel formulation, emission models and advanced numerical techniques partially imported and adapted from the scenario of magnetized neutron stars, on which the PI is expert, IMAGINE will predict values of magnetic fields for different exoplanets, comparing the associated observable properties of gas giants and contributing to identify the best rocky worlds candidates to habitability.