[astro-ph.EP] Planetary magnetic fields shape atmospheric escape, mediate interactions with stellar winds, and encode information about planetary interiors, yet they have not been directly measured for planets beyond the Solar System.
Localization of the radio emission to β Pic b. Frame-tie-corrected radio position (blue; 1,2,3σ covariance ellipses from the Monte Carlo error propagation, including the systematics inflation; Methods) relative to the star β Pictoris (blue star) and its planets b and c (red circles). The uncorrected radio source position is shown for reference in grey, and is consistent with the corrected position within 1 standard deviation. The radio source coincides with β Pic b (Mahalanobis radius R = 1.1, p = 0.53) and is significantly inconsistent with the host star (R = 4.9, 4.4σ) and planet c (R = 5.3, 4.8σ) (Methods). The outermost planet in the system, planet d, lies outside of the frame. — [astro-ph.EP]
A direct observable signature is auroral radio emission produced by the electron cyclotron maser instability, whose highest emitted frequency is set by the magnetic field strength at its source.
Although auroral radio bursts are observed in Solar System planets and in some ultracool dwarfs, no radio detection has previously been unambiguously localized to an extrasolar planet rather than its host star.
Here, we report the first direct detection of auroral radio emission from an exoplanet, the giant planet β Pictoris b, with the MeerKAT array. We detect rapid, recurring, and highly circularly polarized bursts, as well as persistent emission, at frequencies of 0.85 to 3.5 GHz.
We identify the emission as electron cyclotron maser radiation, which implies a magnetic field of ≳1.25 kG at the planet, the first such direct field strength measurement for an exoplanet.
Kevin N. Ortiz Ceballos, Edo Berger, Yvette Cendes
Comments: 32 pages, 9 figures, 3 tables. Submitted
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2609.16720 [astro-ph.EP] (or arXiv:2609.16720v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2609.16720
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Submission history
From: Kevin Ortiz Ceballos
[v1] Tue, 15 Sep 2026 06:44:39 UTC (972 KB)
https://arxiv.org/abs/2609.16720
Astrobiology,
