[astro-ph.IM] Moons orbiting exoplanets (exomoons) can be detected through the reflex motion they impart to their host planet, which is recoverable in relative star-planet astrometric time series.
The signal grows with moon mass and orbital separation and decreases with distance, so the nearest and least massive imaged planets are the most favorable targets. Recovering small (<Earth-mass) moons requires continuous, long-baseline, high-precision monitoring that is only practical with a dedicated or nearly dedicated facility.
Building on recent simulations of astrometric exomoon detection and of the resulting population yields, we argue that the scalable, replicable architecture of the Nautilus Space Observatory is uniquely suited to this problem, and we outline a staged campaign. In an initial phase, one or a few small apertures target the nearest imaged giant planets–a high-reward but low-probability search focused on the closest stars.
As the array is built out, the astrometric noise floor decreases and the same technique extends the search to the nearest such systems among nearby stars of spectral type K and earlier. This would be performed in parallel with high-contrast imaging and spectral characterization of the host planets and in synergy with a companion starshade concept for imaging Earth-like planets around the same nearby stars.
Nautilus thus provides a scalable path from the first detection of a nearby exomoon toward a systematic search for exomoons around the closest stars.
Kevin Wagner, Sumin Seung, Dániel Apai, Enrico Biancalani, Eduardo Bendek, Samantha Hasler, Nadiia Kostogryz, Sowmya Krishnamurthy, Mercedes López-Morales, Peter McGill, Peter Plavchan, Benjamin V. Rackham, Alexander Shapiro, Noah Tuchow, S. Pete Worden, Yifan Zhou
Comments: White Paper for the Nautilus Space Observatory
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2606.28523 [astro-ph.IM] (or arXiv:2606.28523v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2606.28523
Focus to learn more
Submission history
From: Kevin Wagner
[v1] Fri, 26 Jun 2026 18:20:28 UTC (1,298 KB)
https://arxiv.org/abs/2606.28523
Astrobiology, exoplanet, Exomoon, Astronomy,
