Hunting exomoons with a kilometric baseline interferometer

TL;DR

This paper explores how a new optical interferometer with long baselines could enable the detection of Earth-mass exomoons around Jupiter-like planets at distances up to 200 parsecs, advancing exomoon research.

Contribution

It proposes a novel interferometric approach with enhanced baselines and astrometric precision to detect small exomoons around distant exoplanets.

Findings

Interferometer with 1 μas precision can detect Earth-mass exomoons.

Detection feasible around Jupiter-like planets at 50-200 pc.

Longer baselines significantly improve exomoon detection capabilities.

Abstract

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 1$\,\mu$as 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.