JWST studies WD 1856 b, giant planet orbiting white dwarf

Astronomers have discovered how a giant planet survived the violent death of its star and now orbits the stellar remnant at an exceptionally close distance, offering a potential preview of the distant future of our own solar system. The planet, designated WD 1856 b, is located about 80 light-years from Earth and is between four and eleven times more massive than Jupiter, yet it orbits a white dwarf star roughly the size of Earth, completing an orbit every 34 hours.

The findings, based on observations from NASA's James Webb Space Telescope, were detailed in a study published in the journal Nature. Researchers, led by Ryan MacDonald of the University of St. Andrews and including Christopher O'Connor of Northwestern University, used the telescope to measure the planet's atmosphere, mass, and temperature for the first time. They found WD 1856 b has a temperature of about 127 degrees Celsius, which is roughly 240 degrees hotter than would be expected if it were heated solely by the faint white dwarf.

This excess heat provided a crucial clue to the planet's history. By combining the new measurements with models of how giant planets cool over time, the team concluded that WD 1856 b was...