TOI-2338 b, A Dense Circumbinary Gas Giant
TOI-2338 b is a massive circumbinary gas giant with a radius of 11.209 Earth radii orbiting a single-star host system.
Discovered in 2023 via transit telemetry captured by the Transiting Exoplanet Survey Satellite, this heavy world defies simple planetary formation models. With a radius of 11.209 Earth radii and an immense mass of 1900.614 Earth masses, the planet commands a profound gravitational presence within its stellar neighborhood. Its bulk density sits at 7.420 grams per cubic centimeter, while its equilibrium temperature reaches a scorching 799 Kelvin under an insolation flux nearly fourteen times greater than Earth receives.
The orbital architecture of TOI-2338 b involves a complex gravitational dance around its stellar system. The planet completes a full revolution every 22.65398 Earth days along a highly eccentric orbit measuring 0.6760. This elongated path brings the giant world through extreme thermal gradients as it loops around the binary center of mass at a semi-major axis of 0.15800 astronomical units. Gravitational perturbations from the host stars constantly flex the planet's orbit, inducing rapid apsidal and nodal precession over short timescales.
The Thermodynamics of a Hot Circumbinary Giant
Internal temperatures within TOI-2338 b are driven relentlessly upward by the combined thermal output of its parent stars. An equilibrium temperature of 799 Kelvin creates an energetic atmospheric regime where volatile compounds remain entirely in the gas phase. The high stellar insolation flux of 13.85 times Earth drives vigorous vertical mixing throughout the deep envelope. Hydrostatic equilibrium dictates that the massive gaseous envelope supports immense internal pressure gradients, compressing hydrogen and helium far beneath the upper cloud decks.
Radiative transfer models for worlds in this temperature bracket suggest that incoming stellar radiation penetrates deep into the troposphere before scattering back toward space. The intense heat suppresses condensation of standard water ice, leaving higher-temperature silicates and refractory elements to dictate upper atmospheric opacity. Molecular dissociation processes alter the chemical equilibrium of the outer layers, breaking apart simple molecules into reactive atomic radicals.
Gravitational Evolution and Migration Pathways
The current orbital separation of 0.15800 astronomical units represents a migration endpoint rather than a birthplace. Gas giants of this magnitude cannot accrete primordial hydrogen and helium envelopes so close to a stellar system without being torn apart by tidal shear. Instead, TOI-2338 b almost certainly formed much farther out in the original protoplanetary disk before migrating inward via gravitational torque interactions with residual gas and dust.
Orbital eccentricity remains locked at a high value of 0.6760 due to ongoing secular perturbations imparted by the stellar companions. This eccentric geometry guarantees that tidal dissipation continuously injects mechanical energy into the planetary interior over every 22.65-day orbital cycle. The persistent gravitational kneading heats the deep mantle and core regions, opposing standard cooling trends and maintaining an inflated volumetric radius across billions of years of stellar aging.
