James Webb Detects First Exoplanet Atmosphere Around White Dwarf, Finding 7% Methane
Updated
Updated · spacedaily.com · Jul 7
James Webb Detects First Exoplanet Atmosphere Around White Dwarf, Finding 7% Methane
3 articles · Updated · spacedaily.com · Jul 7
Summary
WD 1856 b became the first planet orbiting a white dwarf with a detected atmosphere after Webb observed its April 2023 transit, with results published July 1 in Nature.
Webb’s two-hour near-infrared observation found hydrocarbons—most likely methane making up about 7% of the atmosphere—plus haze particles as the Jupiter-sized planet crossed the Earth-sized star.
126 degrees Celsius night-side warmth also emerged from the data, far above the roughly 160-kelvin temperature expected from the faint white dwarf alone.
That excess heat points to residual warming from a past inward migration, likely 3 to 5.5 billion years after the star became a white dwarf, rather than survival in place through the red-giant phase.
The 80-light-year system offers a rare test case for how giant planets can persist around dead stars, though the methane identification and migration history still need confirmation from four additional Webb transits.
What violent history does this planet's leftover heat and bizarre atmosphere reveal?
This alien world previews our solar system's demise. What does it reveal about Jupiter's future?
Decoding WD 1856 b: JWST Uncovers Methane Atmosphere and Planetary Migration Around a White Dwarf
Overview
The James Webb Space Telescope (JWST) used transmission spectroscopy to study WD 1856 b, revealing a methane-rich atmosphere by analyzing how starlight passes through the planet’s edge. Researchers mapped methane abundance and temperature at different depths, helping them understand how convection patterns work in atmospheres without a solid surface and with heavy condensates. This detailed mapping is important for learning about the structure of gas giants like Jupiter and other hydrogen-rich exoplanets. These findings show how WD 1856 b’s atmosphere fits into the bigger picture of planetary evolution and atmospheric processes.