A temperate super-Jupiter imaged with JWST in the mid-infrared

Abstract

Of the ~25 directly imaged planets to date, all are younger than 500Myr and all but 6 are younger than 100Myr¹. Eps Ind A (HD209100, HIP108870) is a K5V star of roughly solar age (recently derived as 3.7-5.7Gyr² and ${{\boldsymbol{3.5}}}_{-{\bf{1.3}}}^{+{\bf{0.8}}}$Gyr³). A long-term radial velocity trend ^4,5 as well as an astrometric acceleration^6,7 led to claims of a giant planet^2,8,9 orbiting the nearby star (3.6384±0.0013pc¹⁰). Here we report JWST coronagraphic images that reveal a giant exoplanet which is consistent with these radial and astrometric measurements, but inconsistent with the previously claimed planet properties. The new planet has temperature ~275K, and is remarkably bright at 10.65µm and 15.50µm. Non-detections between 3.5-5µm indicate an unknown opacity source in the atmosphere, possibly suggesting a high metallicity, high carbon-to-oxygen ratio planet. The best-fit temperature of the planet is consistent with theoretical thermal evolution models, which are previously untested at this temperature range. The data indicates that this is likely the only giant planet in the system and we therefore refer to it as “b”, despite it having significantly different orbital properties than the previously claimed planet “b”.