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, 22 but the unprecedented sensitivity of JWST NIRCam coronagraphic imaging now provides direct access 23 to planets significantly less massive than Jupiter beyond 10 AU around the closest, youngest M dwarfs. 24 We present the design, observations, and results of JWST GTO Program 1184, a Cycle 1 NIRCam 25 coronagraphic imaging survey of 9 very nearby and young low-mass stars at 3 − 5μm wavelengths. In 26 the F356W and F444W filters, we achieve survey median 5σ contrasts deeper than 10−5 at a separation 27 of 1′′, corresponding to 0.20 MJup in F444W and 1.30 MJup in F356W at planet-star separations of 28 10 AU. Our results include 3 − 5μm debris disk detections and the identification of many extended 29 and point-like sources in the final post-processed images. In particular, we have identified a marginal 30 point source candidate having a flux and color limit consistent with model predictions for a young 31 sub-Jupiter mass exoplanet. Under the assumption that the candidate is not confirmed, we place 32 the first direct-imaging occurrence constraints on M dwarf wide-orbit (semimajor axes 10 − 100 AU), 33 sub-Jupiter mass exoplanets (0.3 − 1 MJup). We find frequency limits of < 0.10 and < 0.16 objects 34 per star with 1 and 3σ confidence, respectively. This survey brings to the forefront the unprecedented 35 capabilities of JWST NIRCam coronagraphic imaging when targeting young, low-mass stars and acts 36 as a precursor to broader surveys to place deep statistical constraints on wide-orbit, sub-Jupiter mass 37 planets around M dwarfs.