Researchers have discovered the afterglow of the catastrophic event that led to the destruction of two ice giant planets. The collision was so violent that the brightness of the system's main star dropped significantly. ASASSN-21qj, a star lingering in space 1,800 light-years from Earth, dimmed in brightness when its two planets collided.
Not only did this cosmic event lead to the complete destruction of both planets, but it also created a donut-shaped dust clump known as Synestia.
Matthew Kenworthy, co-lead author of the study published in the journal Nature, mentioned that the rapidly rotating web of wires would be a truly eye-catching spectacle. The energy from the collision would transform the donut into a star-like object located further away from ASASSN-21qj but about seven times the size of the star.
Kenworthy initiated research to look for the shadows created by the giant rings surrounding planets as they pass in front of their parent star. ASASSN-21qj is an interesting topic because the star's light experienced a sudden and unexplained dimming in December 2021. Kenworthy reached out to amateur astronomers via social networks for help, and NASA "citizen scientist" Arttu Sainio answered the call and studied past observations of the star.
Investigating infrared data collected by the Neowise space telescope, Sainio found evidence that the ASASSN-21qj system experienced a sudden surge of infrared light 900 days before the dimming event. Kenworthy said he had originally been looking for something completely different, but an unexpected spike in infrared radiation caught his attention, indicating that something unusual was clearly happening at the site.
After further analysis of the archived data, scientists concluded that the infrared spike was emitted by the hot Senestia object formed by the collision of two Neptune-sized planets. With temperatures exceeding 700 degrees Celsius, the object will eventually cool and create a new planet.
As noted in the study, it would take about 2.5 years for the afterglow from the planetary collision to destroy the starlight from ASASSN-21qj. During this time, large amounts of dust and tiny debris obscure the star's surface. As Simon Lock, another co-author of the study, points out, this event associated with ASASSN-21qj marks the first time a synapse-related afterglow has been specifically observed.
While debris and protoplanetary disks have been observed before, they were not accompanied by the infrared radiation detected by Neowise. More observations are now planned to verify the synapsis-based explanation, and the James Webb Space Telescope may help detect infrared radiation emitted by newly formed planets within the ASASSN-21qj system.