Constraining an exoplanet’s magnetic field using star-planet interactions

Science 2026 Open access

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Authors: Daniel Revilla, P. J. Amado, R. Luque, P. Schöfer, Antonino Francesco Lanza, A. Binnenfeld, J. A. Caballero, Artie P. Hatzes, G. W. Henry, S. V. Jeffers, Simranpreet Kaur, Ε. Πάλλη
+8 more L. Peña-Moñino, Miguel Ángel Pérez-Torres, A. Quirrenbach, A. Reiners, I. Ribas, Daniele Viganò, M. R. Zapatero Osorio, S. Zucker
DOI: 10.1126/science.adv3075
Cited by: 1
References: 74

Abstract

Theory predicts that a planet with a sufficiently strong magnetic field orbiting close to its host star could induce star-planet magnetic interactions. This is potentially observable as an optical or radio stellar activity signal synchronized with the planet's orbital period. We analyzed 18 years of high-resolution optical spectroscopy of GJ 436, a low-mass star orbited by a Neptune-sized exoplanet on a polar eccentric orbit. Stellar activity indicators show enhancements at a period corresponding to the exoplanet orbit, modulated by stellar rotation, and the star's 8-year magnetic cycle. We interpret this as a signal of star-planet magnetic interaction. Using a geometric model, we reproduced these periods if GJ 436 b has a magnetic field strength of 6 to 110 gauss.

Fields of Study & Subjects

Astrophysics and Star Formation Studies Stellar planetary and galactic studies Astronomy and Astrophysical Research

Publication details

Journal / source
Science
Publisher
American Association for the Advancement of Science (AAAS)
Volume
393
Issue
6809
Pages
403–407
Publication date
25 June 2026
Language
EN