Dust cloud from two colliding ice planets dims light of parent star

For the first time, an international group of astronomers have seen the heat glow of two giant ice planets colliding, and the resultant dust cloud move in front of the parent star several years later. The star ASASSN-21qj - named after the network of telescopes that first detected the fading of the star at visible wavelengths - was then studied intensively by a network of amateur and professional astronomers including those at The University of Warwick, who monitored the changes in the star's brightness over the next two years. The result has been published today in Nature. Co-Author Dr Grant Kennedy, University of Warwick, said: "We think this is the first observation of the glow from the body that is produced by the planetary collision." A chance post on a social media site from an amateur researcher led to the discovery that the system doubled in brightness at infrared wavelengths some three years before the star started to fade in visible light. "To be honest, this was a complete surprise to me," says Co-Author Dr Matthew Kenworthy at Leiden Observatory in the Netherlands. "When the ASASSN survey (an automated programme searching for new supernovae, based at Ohio State University) shared the light curve of this star with other astronomers, I started watching it with a network of telescopes and observers. Out of the blue, an astronomer on social media pointed out that the star brightened up in the infrared over a thousand days before the optical fading.