JWST/MIRI coronagraphic search for planets in systems with gapped exoKuiper belts and proper motion anomalies

TL;DR

This study uses JWST/MIRI coronagraphic observations to search for planets in systems with gapped exoKuiper belts, constraining potential planet properties responsible for observed disc structures and proper motion anomalies.

Contribution

First JWST/MIRI coronagraphic survey targeting gapped exoKuiper belts, providing new constraints on unseen planets shaping debris disc structures.

Findings

No planets detected in the observed systems.

Stringent limits placed on possible planet masses and locations.

Inner 20 au likely hosts planets causing proper motion anomalies.

Abstract

Over the past decade, ALMA has uncovered a range of substructures within exoKuiper belts, pointing to a population of undetected planets. With JWST's sensitivity, we now have the opportunity to identify these planets thought to be responsible for the observed substructures in debris discs. We present Cycle 1 JWST/MIRI 11.4 {\mu}m coronagraphic observations of three exoKuiper belts that exhibit gaps in their radial structures: HD 92945, HD 107146, and HD 206893, to determine whether planets are responsible for carving these structures, as seen in our Solar System with the gas giants. We reduce the JWST/MIRI data using spaceKLIP, and introduce new routines to mitigate the Brighter-Fatter effect and persistence. We do not detect any planet candidates, and all detected objects in the field-of-view are consistent with background stars or galaxies. However, by combining JWST mass limits, archival observational constraints, and astrometric accelerations, we rule out a significant portion of planet parameter space, placing tight constraints on the planets possibly responsible for these gaps. To interpret these results, we explore multiple gap-carving scenarios in discs, either massless or with non-zero mass, including clearing by in-situ planet(s), as well as shaping by inner planets through mean-motion or secular apsidal resonances. Finally, we conclude that the planets causing the proper motion anomaly in these systems must reside within the inner 20 au.