First-Ever Visual Documentation of Enormous Planetary Collision’s Aftermath

The image depicts a simulation of the expansive, luminous body generated as a result of a planetary impact. In the immediate view, shards of ice and rock are propelled from the point of impact, and are predicted to later traverse the space between Earth and the parent star, visible in the image’s backdrop. Credit: Mark Garlick

A global group of astronomers has documented the collision of two ice giant exoplanets orbiting a star similar to our sun, giving rise to a powerful surge of light and a cloud of particulates. This groundbreaking revelation may pave the way for the genesis of additional moons orbiting a nascent planet in the foreseeable future.

The research, disclosed today (October 11) in the journal Nature, elucidates the occurrence of two ice giant exoplanets colliding in the vicinity of a sun-like star, culminating in a brilliant flare of light and billowing plumes of particulate matter. The investigation reveals the vivid thermal afterglow and the subsequent dust cloud that obscured the parent star progressively.

A Joint Observational Initiative

The consortium of international astronomers was assembled following an enthusiast’s scrutiny of the star’s light curve, which displayed peculiar characteristics. The data indicated a two-fold increase in the star’s infrared brightness approximately three years prior to its dimming in the visible light spectrum.

Dr. Matthew Kenworthy, Co-Lead Author from Leiden University, stated, “Frankly, this observation caught me off guard. As we disseminated the visible light curve data among the astronomical community, we commenced an extensive observation campaign employing a series of telescopes.”

“A colleague using social media noted the star’s increase in infrared brightness more than a thousand days preceding its dimming in visible light. I immediately understood that we were witnessing an extraordinary event.”

Stellar Surveillance and Analysis

Over an ensuing two-year period, a team of both professional and amateur astronomers intensively observed changes in the star’s luminosity. The star received the designation ASASSN-21qj, named after the observational network that initially identified the star’s diminishing brightness in the visible spectrum.

After comprehensive analysis, the research team posited that the most plausible scenario was a collision between two ice giant exoplanets, as corroborated by infrared illumination detected by NASA’s NEOWISE mission, an initiative that employs a space telescope to track asteroids and comets.

Input from Co-Lead Scientists

Dr. Simon Lock, Research Fellow in Earth Sciences at the University of Bristol and co-lead author, elaborated, “Our computational simulations and numerical analyses are in line with the dimensions and temperature of the radiant material, along with the duration of the luminescence, which corroborate the theory of an ice giant exoplanet collision.”

The ensuing expansive cloud of debris from the impact event subsequently transited in front of the parent star roughly three years later, leading to a gradual attenuation of the star’s brightness in visible wavelengths.

Upcoming Observations and Forecasts

In the years to come, it is anticipated that the dust cloud will disperse along the orbital trajectory of the collision remnants. Astronomers may discern light scattering from this cloud through both terrestrial telescopes and NASA’s most advanced space telescope, known as JWST.

Future scrutiny of the system is a high priority for the astronomers involved.

Dr. Zoe Leinhardt, Co-author and Associate Professor of Astrophysics at the University of Bristol, added, “Future observations will undoubtedly be riveting. Ultimately, it is plausible that the aggregate matter surrounding the collision remnant could coalesce, giving rise to a new assembly of moons in orbit around the emergent planet.”

Reference: “A planetary collision afterglow and transit of the resultant debris cloud” by Matthew Kenworthy, Simon Lock, Grant Kennedy, Richelle van Capelleveen, Eric Mamajek, Ludmila Carone, Franz-Josef Hambsch, Joseph Masiero, Amy Mainzer, J. Davy Kirkpatrick, Edward Gomez, Zoë Leinhardt, Jingyao Dou, Pavan Tanna, Arttu Sainio, Hamish Barker, Stéphane Charbonnel, Olivier Garde, Pascal Le Dû, Lionel Mulato, Thomas Petit, and Michael Rizzo Smith, published on 11 October 2023 in Nature.
DOI: 10.1038/s41586-023-06573-9

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More about Planetary Collision

• Nature Journal Publication
• NASA’s NEOWISE Mission
• Leiden University Astronomy Department
• University of Bristol Earth Sciences
• ASASSN Telescope Network
• JWST Space Telescope