Probing the Outskirts of M Dwarf Planetary Systems with a Cycle 1 JWST NIRCam Coronagraphy Survey

The population of giant planets on wide orbits around low-mass M dwarf stars is poorly understood, but the unprecedented sensitivity of JWST NIRCam coronagraphic imaging now provides direct access to planets significantly less massive than Jupiter beyond 10 au around the closest, youngest M dwarfs. We present the design, observations, and results of JWST Guaranteed Time Observation Program 1184, a Cycle 1 NIRCam coronagraphic imaging survey of nine very nearby and young low-mass stars at 3–5 μm wavelengths. In the F356W and F444W filters, we achieve survey median 5σ contrasts deeper than 10−5 at a separation of 1″, corresponding to 0.20 MJup in F444W and 1.30 MJup in F356W at planet–star separations of 10 au. Our results include 3–5 μm debris disk detections and the identification of many extended and point-like sources in the final postprocessed images. In particular, we have identified a marginal point-source candidate having flux and color limits consistent with model predictions for a young sub-Jupiter-mass exoplanet. Under the assumption that the candidate is not confirmed, we place the first direct-imaging occurrence constraints on M dwarf wide-orbit (semimajor axes of 10–100 au), sub-Jupiter-mass exoplanets (0.3–1 MJup). We find frequency limits of <0.10 and <0.16 objects per star with 1σ and 3σ confidence, respectively. This survey showcases the unprecedented capabilities of JWST NIRCam coronagraphic imaging when targeting young, low-mass stars and acts as a precursor to broader surveys to place deep statistical constraints on wide-orbit, sub-Jupiter-mass planets around M dwarfs.