Glowing cosmic cloud reveals cataclysmic collision

A cataclysmic crash of two giant exoplanets - planets outside our solar system - left behind the cloud and one single molten core, which is still orbiting the star.

The story behind this discovery

Scientists were observing a young, 300-million-year-old, Sun-like star when they noticed an unusual and significant drop in the star's brightness. Upon close investigation, researchers found that, just before this dip, the star displayed a sudden spike in infrared luminosity, which lasted for 1,000 days.

Notably, about 2.5 years into this period of heightened brightness, an eclipse occurred, causing the star's brightness to suddenly diminish for 500 days.

Further investigation revealed that the culprit behind both the spike in luminosity and the eclipse was a giant, glowing cloud of gas and dust. And the most likely reason for the sudden, eclipse-causing cloud? The researchers think that a violent cosmic collision between two exoplanets, one of which likely contained ice.

Scientists believe that two giant exoplanets anywhere from several to tens of Earth masses crashed into one another, creating both the infrared spike and the cloud. A collision of this intensity would have liquefied both planets, resulting in a singular molten core surrounded by a cloud of gas, hot rock, and dust.

This cloud, still containing the hot remnants of the collision, continued its orbit around the star, eventually passing in front of it and eclipsing it.

This discovery was made possible through archival data from NASA's WISE mission, which now operates as NEOWISE, and initial detection of the star by the ASAS-SN (All-Sky Automated Survey for Supernovae) survey in 2021.

The research team is now putting together proposals to observe the system with NASA's James Webb Space Telescope (JWST) to gain further insights into the aftermath of this colossal planetary collision.

When giants collide 💥 A dramatic change in a star's luminosity was caused by a giant, glowing cloud of dust. And the likely cause? A cataclysmic crash of two giant exoplanets, leaving behind the cloud and one single molten core, still orbiting the star. https://t.co/rZXJ6kZd6s pic.twitter.com/2SFaignZTT

— NASA Exoplanets (@NASAExoplanets) February 16, 2024