JWST Coronagraphic Images of 14 Her c: a Cold Giant Planet in a Dynamically Hot, Multi-planet System

TL;DR

The paper reports the first direct imaging of a cold, mature exoplanet in a dynamically hot, multi-planet system using JWST, revealing insights into planetary formation and atmospheric composition.

Contribution

It presents the discovery and characterization of 14 Her c, the first cold exoplanet in a dynamically hot system, highlighting its unique orbital and atmospheric properties.

Findings

14 Her c is a cold, mature exoplanet directly imaged by JWST.

The system shows large eccentricities and mutual inclinations, indicating a turbulent past.

Atmospheric analysis suggests carbon disequilibrium chemistry and water ice clouds.

Abstract

Most observed multi-planet systems are coplanar, in a dynamically "cold" configuration of concentric orbits like our own Solar System. With the James Webb Space Telescope (JWST) we have detected 14 Her c, the first mature and cold exoplanet directly imaged in a dynamically "hot", multi-planet system. With large eccentricities and a nonzero mutual inclination, the present-day architecture of this system points to a turbulent past and ongoing angular momentum exchange between the planetary orbits of 14 Her b and c. The temperature of 14 Her c rivals both the coldest imaged exoplanet and the coldest known brown dwarf. Moreover, its photometry at 4.4 mu is consistent with the presence of carbon disequilibrium chemistry and water ice clouds in its atmosphere. 14 Her c presents a unique laboratory to study giant planet formation, dynamical evolution of multi-planet system architectures, and atmospheric composition and dynamics in extremely cold worlds.