Constraining an exoplanet’s magnetic field using star-planet interactions
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 synchronised with the planet's orbital period. We analyze 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 reproduce these periods if GJ 436 b has a magnetic field strength of 6 to 110 Gauss.
Authors
- A. Reiners (ORCID: https://orcid.org/0000-0003-1242-5922)
- R. Luque (ORCID: https://orcid.org/0000-0002-4671-2957)
- P. Schöfer (ORCID: https://orcid.org/0000-0002-5969-3708)
- Ε. Πάλλη (ORCID: https://orcid.org/0000-0003-0987-1593)
- M. R. Zapatero Osorio (ORCID: https://orcid.org/0000-0001-5664-2852)
- A. F. Lanza (ORCID: https://orcid.org/0000-0001-5928-7251)
- J. A. Caballero (ORCID: https://orcid.org/0000-0002-7349-1387)
- P. J. Amado (ORCID: https://orcid.org/0000-0002-8388-6040)
- Daniele Viganò (ORCID: https://orcid.org/0000-0001-7795-6850)
- M. Á. Pérez-Torres (ORCID: https://orcid.org/0000-0001-5654-0266)
- S. Zucker (ORCID: https://orcid.org/0000-0003-3173-3138)
- S. V. Jeffers (ORCID: https://orcid.org/0000-0003-2490-4779)
- A. P. Hatzes (ORCID: https://orcid.org/0000-0002-3404-8358)
- I. Ribas (ORCID: https://orcid.org/0000-0002-6689-0312)
- Daniel Revilla (ORCID: https://orcid.org/0000-0002-3897-5976)
- Simranpreet Kaur (ORCID: https://orcid.org/0000-0002-5820-2532)
- L. Peña-Moñino (ORCID: https://orcid.org/0000-0001-6735-1655)
- A. Binnenfeld (ORCID: https://orcid.org/0000-0002-9319-3838)
- A. Quirrenbach
- G. W. Henry
Institutions
- Universitat Autònoma de Barcelona (ES)
- Universidad de La Laguna (ES)
- Tel Aviv University (IL)
- European University Cyprus (CY)
- Heidelberg University (DE)
- University of Chicago (US)
- Institut d'Estudis Espacials de Catalunya (ES)
- Exact Sciences (United States) (US)
- Osservatorio Astrofisico di Catania (IT)
- Centro de Astrobiología (ES)
- Instituto de Astrofísica de Canarias (ES)
- Institut de Ciència de Materials de Barcelona (ES)
- Thüringer Landessternwarte Tautenburg (DE)
- Fundació Universitat-Empresa de les Illes Balears (ES)
- Instituto de Astrofísica de Andalucía (ES)
- Universitat de les Illes Balears (ES)
- University of Göttingen (DE)
- Tennessee State University (US)
- National Institute for Astrophysics (IT)
Publication Details
- Journal
- Science
- Published
- 2026-06-25
- DOI
- https://doi.org/10.1126/science.adv3075
- Primary Topic
- Astrophysics and Star Formation Studies
- Type
- article
- Field-Weighted Citation Impact
- 0.00