Hunting Exomoons With A Kilometric Baseline Interferometer

Despite numerous search campaigns based on a diverse set of observational techniques, exomoons – prospective satellites of extrasolar planets – remain an elusive and hard-to-pin-down class of objects.

Yet, the case for intensifying this search is compelling: as in the Solar System, moons can act as proxies for studying planet formation and evolution, provide direct clues as to the migration history of the planetary hosts and, in favourable cases, offer potentially habitable environments.

Here, we present an investigation into how the search for exomoons would benefit from a new interferometric facility operating in the optical wavelength domain and leveraging baselines substantially longer than the ones the VLTI is currently equipped with.

We find that an interferometer providing an astrometric precision of 1μas would be able to robustly detect Earth-mass and sub-Earth-mass exomoons on dynamically stable orbits around Jupiter-like planets at distances between 50 and 200 pc.

Thomas O. Winterhalder, Antoine Mérand, Sylvestre Lacour, Jens Kammerer, Guillaume Bourdarot, Frank Eisenhauer

Comments: ESO Expanding Horizons White Paper
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2512.15858 [astro-ph.IM] (or arXiv:2512.15858v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2512.15858
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Submission history
From: Thomas Winterhalder
[v1] Wed, 17 Dec 2025 19:00:02 UTC (1,381 KB)
https://arxiv.org/abs/2512.15858

Astrobiology, Exoplanet,