Astronomers observe a rare cosmic collision between worlds of ice
Scientists have spotted an unknown phenomenon 1800 light years from Earth.
Two huge ice worlds clash in a devastating cosmic collision, leaving a cloud of dust and a hot rotating object about a hundred times the size of Earth.
It sounds like the opening of a space fantasy movie, but this is what a team of astronomers believe to have happened based on the evidence around a star now labelled ASASSN-21q, which is located 1800 light years from Earth.
Previously this star went by the more anonymous name of 2MASS J08152329-3859234, living a generally quiet life as a glowing ball of plasma. But in December 2021, the light from this otherwise dull star suddenly became significantly dimmer, a phenomenon that had been observed before, but which nevertheless attracted the attention of the world’s astronomers.
Then an amateur astronomer on social media commented on the star’s visible light curve, pointing out that it had become dramatically lighter in its infrared wavelengths 900 days earlier.
This took the phenomena from rare to entirely unprecedented.
“To be honest, this observation was a huge surprise to me,” says one of the researchers behind a study of the event, Matthew Kenworthy from Leiden University. After a detailed analysis of both the infrared radiation and the subsequent dimmed optical light, the astronomers came to the conclusion that such a sudden explosion of infrared radiation must have come from a planet-like hot object produced after the collision of two planets the size of Neptune. The dim light was probably the result of a massive cloud of dust and dirt from the collision passing in front of the star around 2.5 years after the collision, while the huge space object was probably 700+°C hot for about three years. It will cool and form a new planet orbiting the star, according to the astronomers, while the cloud of material around the remnant may condense to form a retinue of moons orbiting the new planet.
We have observed dust and dirt from a planetary collision before, but according to the astronomers this is the first time we have seen the afterglow of the planet-like object produced in such cosmic collisions.