A glowing cosmic cloud points to a collision.

A luminous cosmic cloud has unveiled the aftermath of a cataclysmic collision, echoing the traces of colossal planetary crashes witnessed even within our solar system. The enduring imprints, such as the distinctive tilt of Uranus and the formation of Earth’s Moon, bear witness to ancient planetary collisions that have reshaped their positions and characteristics. Expanding their gaze beyond our solar system, scientists examining distant exoplanets have identified analogous evidence of planetary clashes across the universe. In this latest study, the remnants of such an impact manifest in a peculiar cloud of dust and gas, characterized by an intriguing, fluctuating luminosity.

In a captivating celestial observation, scientists scrutinizing a youthful Sun-like star, approximately 300 million years old, stumbled upon an intriguing anomaly. The star underwent a sudden and substantial dimming, prompting a closer investigation that unveiled a preceding surge in infrared luminosity lasting 1,000 days. Astonishingly, 2.5 years into this radiant phase, the star encountered an unexpected eclipse lasting 500 days, shrouding it in darkness. Deeper exploration revealed a colossal, luminous cloud of gas and dust as the culprit behind both the luminosity spike and the subsequent eclipse. The leading explanation for this cosmic spectacle points to a collision between two exoplanets, with one likely harboring ice—an event that left an indelible mark on the stellar canvas.

In a comprehensive study elucidating these extraordinary celestial occurrences, scientists propose a dramatic scenario: the collision of two massive exoplanets, ranging from several to tens of Earth masses. This cosmic clash not only generated the observed infrared luminosity spike but also gave rise to a luminous cloud composed of gas, hot rock, and dust. The intensity of the collision would have completely liquefied the two planets, leaving behind a singular molten core enveloped by the aftermath. Following this cataclysmic event, the residual cloud, still carrying the remnants of the collision, continued its orbital path around the star. Eventually, it positioned itself in front of the star, initiating an eclipse as it cast its cosmic shadow, providing a mesmerizing spectacle for astronomers to unravel.

This investigation utilized archival data from NASA’s retired WISE mission, now operating as NEOWISE, with the star under scrutiny initially identified in 2021 by the ASAS-SN ground-based robotic survey. While these data unveiled remnants of a planetary collision, the luminous aftermath of this celestial crash remains detectable by advanced telescopes such as NASA’s upcoming James Webb Space Telescope.The research team, led by Matthew Kenworthy and comprising 21 co-authors, has already begun crafting proposals for observations with the Webb telescope. The study, titled “A planetary collision afterglow and transit of the resultant debris cloud,” was published on October 11, 2023, in the journal Nature, providing a comprehensive exploration of this cosmic spectacle.