An international team of astronomers has observed for the first time a thermal afterglow resulting from the collision of two icy exoplanets. The cloud formed by the cataclysm led to a change in the brightness of the star.
The described events took place in the vicinity of the sun-like star ASASSN-21qj, which is located at a distance of 1800 light years from Earth. A few years ago, it began to fade in the visible range, which attracted the attention of researchers. Then the scientists noticed a message left on social media by an amateur astronomer. He pointed out that a thousand days before optical extinction, ASASSN-21qj became twice as bright in the infrared.
Later, astronomers managed to understand the causes of these strange events. They concluded that the most likely explanation was a collision between two giant ice planets. It led to the formation of an expanding debris cloud, which initially increased the infrared brightness of the system. After about three years, this cloud shifted to a point located between the star and the Earth, which led to a decrease in its luminosity in the visible range.
These conclusions are consistent with the results of computer modeling. It showed that the collision occurred at a distance of 2 to 16 a. о. from the star and involved two bodies with a mass of several tens of Earth’s masses.
The collision led to the merger of two exoplanets into a single object. Apparently, a large amount of water vapor was emitted during the event, which helped cool the newborn planet to a temperature of 730 °C. In the future, the remaining matter around this body may condense into a number of satellites. As for the dust cloud, it will gradually dissipate into orbit. This will make it possible to study the consequences of the collision with the help of telescopes.
