Astronomers from MIT have identified a rocky exoplanet, BD+05 4868 Ab, situated around 140 light-years away, that is breaking apart under extreme heat. The planet orbits its host star every 30.5 hours at a distance much closer than Mercury is to the Sun.
The planet was detected using NASA’s Transiting Exoplanet Survey Satellite (TESS). Scientists noticed irregular dips in the light from the star BD+05 4868 A, suggesting the presence of a body with a trailing cloud of debris.
The crumbling planet has a debris trail stretching up to 9 million kilometres, roughly half the length of its orbit. The length and variability of the trail indicate continuous material loss from the planet’s surface.
Researchers estimate the planet sheds material equivalent to the mass of Mount Everest every time it completes an orbit. Based on its size and low mass—comparable to Mercury—the planet may fully disintegrate within 1 to 2 million years.
Due to its close orbit, BD+05 4868 Ab is estimated to reach temperatures around 1,600°C. The intense heat likely causes surface minerals to vaporise, forming a dust-based tail similar in appearance to a comet’s, but with no volatile ices.
The planet is one of only four known exoplanets undergoing disintegration. It has the most prominent tail and deepest transit signature among them, indicating more rapid evaporation than the others observed previously with the Kepler Space Telescope.
Given the brightness of the host star, the system is well-suited for study using the James Webb Space Telescope (JWST). Scientists plan to examine the mineral composition of the dust to better understand the interior of rocky planets beyond our solar system.