Astronomers have recorded the collision of two icy planets for the first time. The collision caused a thermal flare and then a huge cloud of debris that blocked the light of a giant star.
The amount of light emitted by the star ASASSN-21 qj suddenly decreased. When this was observed, it was not immediately clear what caused the decline. Under the leadership of Leiden astronomer Matthew Kenworthy, the star’s brightness was monitored for two years.
A researcher’s social media post made a remarkable discovery. Three years before the star began to dim, the star suddenly gave off more infrared light. The US NEOWISE mission saw this.
According to scientists from Leiden University, there is only one logical explanation: it was a collision between two icy planets. In such a collision, first a thermal flare and then a cloud of debris are generated.
The collision explains the increase in infrared light. When the cloud of debris passed near the star, the light of the giant star faded. Computer models and collision calculations match the observations, according to Simon Locke, co-author from the University of Bristol in the United Kingdom.
Observations of the collision could provide new insights into the interiors of these massive icy planets. The heavy metals of these planets are usually covered by a thick layer of hydrogen and helium. But the collision brings everything together. Then more information can be found.
“We’re watching this closely to see what happens next,” Kenworthy said.