Overview
- JWST’s NIRSpec secondary-eclipse measurements put the planet’s dayside near 1,800°C, well below the ~2,700°C expected for a bare rock.
- The Carnegie-led study, published December 11 in The Astrophysical Journal Letters, reports the strongest evidence yet for an atmosphere on this rocky world.
- Continuous 37-hour observations in JWST General Observers Program 3860 covered nearly four orbits to produce these first results.
- Scenarios involving magma heat transport or a thin rock-vapor layer fail to explain the magnitude of the cooling seen in the data.
- The authors propose an outgassing–reabsorption balance could sustain a long-lived atmosphere under extreme irradiation, with further analysis underway to map temperatures and identify gases.