Astronomers Witness Planetary Collision 11,000 Light-Years Away
In a rare cosmic event, astronomers have observed what appears to be the collision of two planets orbiting a star 11,000 light-years from Earth. The dramatic event was detected around a star called Gaia20ehk, located near the constellation Puppis.
Discovery and Initial Observations
The discovery began when Anastasios (Andy) Tzanidakis, a doctoral candidate in astronomy at the University of Washington, was reviewing archived telescope observations from 2020. He noticed unusual fluctuations in the star’s brightness.
Gaia20ehk is a stable “main sequence” star, similar to our Sun, and typically exhibits consistent brightness. However, starting in 2016, the star began to show three dips in brightness, followed by a period of erratic flickering around 2021. “The star’s light output was nice and flat, but starting in 2016 it had these three dips in brightness. And then, right around 2021, it went completely bonkers,” said Tzanidakis.
Evidence Points to a Planetary Collision
Researchers determined the strange behavior wasn’t originating from the star itself. Instead, the light from Gaia20ehk was being blocked by vast clouds of hot dust and debris orbiting the star. The most likely explanation is a violent collision between two planets, scattering material throughout the system.
“I can’t emphasize enough that stars like our sun don’t do that. So when we saw this one, we were like ‘Hello, what’s going on here?’” Tzanidakis explained.
Infrared Observations Confirm the Findings
Further analysis, guided by James Davenport, another researcher from the University of Washington, involved examining observational data in the infrared spectrum. This revealed a surprising correlation: when visible light dimmed, infrared light sharply increased. This suggests the debris surrounding the star is extremely hot.
Significance of the Discovery
Planetary collisions are believed to be common during the early stages of solar system formation. This observation provides a rare opportunity to witness such an event in real-time, offering insights into the chaotic processes that may have shaped our own solar system, including the potential formation of Earth’s moon.
“It’s extraordinary that telescopes managed to capture this collision in real time,” said Tzanidakis. “He said very few planetary collisions had been observed before. Even events that are similar to the formation processes of the Earth and Moon have almost never been detected directly.”
The team’s research was published on March 11 in The Astrophysical Journal Letters, titled “Gaia-GIC-1: An Evolving Catastrophic Planetesimal Collision Candidate.”