"Crazy" light curve: Collision of two exoplanets likely observed in real time
In old measurement data, two US researchers found a star that appeared "completely crazy." Apparently, there was a catastrophic collision in its orbit.
Artistic representation of the collision
(Image: Andy Tzanidakis)
Two researchers from the USA have apparently discovered observation data from several telescopes that show the collision of two exoplanets in another star system in real time. The University of Washington from the US state of the same name has now made this public. The star system Gaia20ehk was found in data from the European space telescope Gaia, which delivered “completely crazy” data on the brightness of the star, 11,000 light-years away. But only an analysis of infrared data then provided the crucial clue as to what had triggered the chaotic flickering of the star. The collision responsible reminds the research team of that of the early Earth four and a half billion years ago. The debris cloud is even about as far from its star as the Earth is from the sun.
“Completely crazy” data
The brightness values of Gaia20ehk were inconspicuous until 2016, explains study leader Anastasios Tzanidakis. That is, on a timeline, the measurement values result in a “nice, flat” line. From 2016 onwards, however, there are three noticeable drops in brightness, the first of which was the most significant. “But then, in mid-2021, everything suddenly became completely crazy,” explains the astronomer, adding, “I can't emphasize enough that sun-like stars don't do that.” He and his team thought, “Hello, what's going on here?” Even these measurements had indicated a massive dust cloud that obscured the star and must have arisen from a gigantic collision. “It's incredible that different telescopes have captured this impact in real time,” says Tzanidakis.
(Image:Â Tzanidakis et al./The Astrophysical Journal Letters)
This sequence of brightness drops and a subsequent complete chaos had never been observed before, writes the astronomer. His colleague James Davenport then suggested consulting measurement data in the infrared spectrum. And indeed, the measurement curve in this spectrum was the complete opposite. As the visible light began to flicker, the star became brighter in the infrared spectrum. This could mean that the blocking material is very hot, the team cautiously suggests. A catastrophic collision between two exoplanets in the star system “would certainly produce enough heat.” Moreover, it would fit the drops in brightness, which would then show how the two planets have increasingly approached each other.
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The research team does not have final proof for their hypothesis, but according to them, the evidence strongly suggests it. This would mean that Gaia and the other telescopes may have observed an event at Gaia20ehk that the Earth has also gone through. 4.5 billion years ago, our home planet collided with the gigantic protoplanet Theia, which among other things created the moon. Both celestial bodies were neighbors before. Further investigation of Gaia20ehk may now also shed light on what exactly happened at that time. For example, it is unclear how long the gigantic dust cloud will obscure the star. This could take years or millions of years, writes the team. The discovery has been presented in The Astrophysical Journal Letters.
(mho)
