1st evidence of giant exoplanet collision afterglow explains unusual eclipse

An international team of astronomers has reported the first-ever observations of the aftermath of a collision between two giant planets in another solar system. The collision was first detected in December 2021 when the host star of the planetary system, 2MASS J08152329-3859234, dimmed. Follow-up observations suggest that the dimming was due to an eclipse caused by debris from the collision, which lasted about 500 days.

The astronomers used computer model data to determine the size and temperature of the eclipsing material, leading them to conclude that the debris was the result of a collision between two super-Earths, or ice giants larger than Earth but smaller than Neptune. The star around which these planets orbit is estimated to be about 300 million years old, much younger than our 4.6 billion-year-old Sun.

Such collisions were common in the early history of our own solar system, but ceased around 3.9 billion years ago. However, this discovery suggests that collisions may also occur between mature planets. Future observations with NASA’s James Webb Space Telescope could provide more insights into how the dust cloud from the collision disperses over time.

The researchers also speculate that the mass of material around the remnant of the collision may eventually form a group of moons orbiting a new planet. These findings were published in the journal Nature on October 11.