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Astronomers say they’ve spotted evidence of a cataclysmic collision between two distant planets.
In addition to sending a shiver up our spines, the resulting study published in the journal The Astrophysical Journal Letters could also provide new insight into the evolution of our own solar system — and perhaps even how the Earth got its Moon.
The clues to this cosmic tragedy come from a main sequence star known as Gaia20ehk. It by all accounts seemed thoroughly ordinary, burning at a steady brightness like our Sun. That is, until it began flickering out of control.
“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 lead author Anastasios Tzanidakis, an astronomer at the University of Washington, in a statement about the work.
“I can’t emphasize enough that stars like our Sun don’t do that,” he added. “So when we saw this one, we were like ‘Hello, what’s going on here?'”
The star, it turned out, wasn’t flickering like a giant dying lightbulb. Instead, the dark patches were caused by huge streams of rock and dust passing in front of it. The quantities would have to be enormous to even partially blot out starlight, so the astronomers say the most likely explanation was that they’re the debris from a planetary collision.
Observations taken with another telescope corroborated this theory. In the infrared data, the light curve spiked while the visible light dimmed. This “could mean that the material blocking the star is hot — so hot that it’s glowing in the infrared.”
A collision between two massive bodies would produce these levels of heat. Before a brutal bodyslam, the planets would’ve been locked in a morbid dance.
“That could be caused by the two planets spiraling closer and closer to each other,” Tzanidakis said. “At first, they had a series of grazing impacts, which wouldn’t produce a lot of infrared energy. Then, they had their big catastrophic collision, and the infrared really ramped up.”
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