Exoplanets & Exomoons

On The Required Mass For Exoplanetary Radio Emission

By Keith Cowing
Status Report
December 8, 2023
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On The Required Mass For Exoplanetary Radio Emission
Known explanets (as of 2023-03-01), based on exoplanet. eu (Schneider et al., 2011). Blue area: Planets with an orbital distance d < 0.2 AU, and a planetary mass M in the range 0.01 < M ≤ 2MJ ). In this parameter space, an extended planetary atmosphere could potentially lead to radio quenching. -- astro-ph.EP

The detection of radio emission from an exoplanet would constitute the best way to determine its magnetic field.

Indeed, the presence of a planetary magnetic field is a necessary condition for radio emission via the Cyclotron Maser Instability. The presence of a magnetic field is, however, not sufficient. At the emission site, the local cyclotron frequency has to be sufficiently high compared to the local plasma frequency.

As strong stellar insolation on a low-mass planet can lead to an extended planetary atmosphere, the magnetospheric plasma frequency depends on the planetary mass, its orbital distance, and its host star. We show that an extended planetary atmosphere can quench the radio emission. This seems to be true, in particular, for an important fraction of the planets less massive than approximately two Jupiter masses and with orbital distances below ∼0.2 AU.

Most of the best candidates suggested by radio scaling laws lie in this parameter space. Taking this effect quenching into account will have important implications for the target selection of observation campaigns. At the same time, this effect will have consequences for the interpretation of observational data.

Jean-Mathias Grießmeier, N. V. Erkaev, C. Weber, H. Lammer, V. A. Ivanov, P. Odert

Comments: 6 pages, 1 figure. Proceedings of Planetary, Solar and Heliospheric Radio Emissions IX (2023)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2312.03888 [astro-ph.EP] (or arXiv:2312.03888v1 [astro-ph.EP] for this version)
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Submission history
From: Jean-Mathias Grießmeier
[v1] Wed, 6 Dec 2023 20:25:54 UTC (106 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻