The cause of a mysterious strange glow in space may finally have been solved by scientists. The peculiar blaze of light, which has stumped researchers for more than four years, may have been produced by the collision of two ice giant exoplanets.
These planets could have been similar in size to the ice giants in our own Solar System – Neptune and Uranus – according to new research published in Nature journal.
An initial observation by an astronomy enthusiast saw the brightness double around a distant Sun-like star around 1,800 light years from Earth. Afterwards, the brightness began to fade three years later.
“To be honest, this observation was a complete surprise to me,” said co-lead author Dr Matthew Kenworthy, from Leiden University.
“An astronomer on social media pointed out that the star brightened up in the infrared over a thousand days before the optical fading. I knew then this was an unusual event.”
The afterglow was detected by NASA’s NEOWISE mission using a space telescope that searches for asteroids and comets.
Then, using calculations and computer models based on the temperature and size of the glowing material, scientists theorised several possible causes. The most likely: the glow was caused by the collision of two ice giants.
If this conclusion is correct, the dimming of the intense light would have been caused by a dust cloud moving in front of the star.
Over the coming years, Earth and off-planet telescopes, including the James Webb Space Telescope (JWST), will make further observations. These may spot a cloud of dust spreading over the collision site, which the telescopes would pick up as a scattering of light.
This is because the collision sent fragments of rock and ice flying around the star, creating a glowing planetary body.
In the future, the researchers say that this material circling around the remnant of the collision may condense to form a string of moons that will orbit the new planet.
“This sighting offers our first real-time glimpse into the workings of giant impacts, collisions between planets, and how systems evolve afterwards,” co-lead author Dr Simon Lock told BBC Science Focus.
“In affect, we will be able to watch the final stages of the birth of a planet.”
Note: Main image is only an illustration of the afterglow, provided by Mark Garlick.
About our expert
Dr Simon Lock is a Research Fellow in Earth Sciences at the University of Bristol. His research has been published in The Planetary Science Journal and the Journal of Geophysical Research.
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