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last mo.

JWST Shows Jupiter‑Size Planet Migrated Into Close Orbit Around a White Dwarf

Thermal-history models and JWST transit spectroscopy indicate the planet heated billions of years after the star died, favoring late gravitational migration.

Dentro de unos 5 000 millones de años, el Sol agotará el hidrógeno de su núcleo. A partir de ese momento se convertirá en una gigante roja cuyo tamaño crecerá más de cien veces respecto al actual.
Gracias al telescopio espacial James Webb, el equipo pudo estudiar la atmósfera, la masa y la temperatura del planeta

Overview

  • An international team led from the University of St Andrews used JWST NIRSpec during an eight-minute transit to measure WD 1856 b’s atmosphere, temperature and mass and reported the results in Nature.
  • The planet orbits a white dwarf at about 0.02 astronomical units with a 1.4-day period, has an estimated mass of 4–11 Jupiter masses, and shows hydrocarbons, hazes and clouds in its atmosphere.
  • Measured dayside temperatures near 400 kelvin are far higher than passive cooling would allow, so researchers ran thermal-evolution models to reconstruct when the planet was heated.
  • Models date the heating event to roughly 3–5.5 billion years after the host became a white dwarf, a timing that strongly favors a late inward migration driven by multi-body gravitational interactions over survival inside the star’s giant envelope.
  • The result shows planetary systems can rearrange long after stellar death and implies that gas giants like Jupiter could undergo late, chaotic orbital shifts in the far future while key dynamical details remain under study.