NASA’s Spitzer Space Telescope has spotted an eruption of dust around a young star, possibly the result of a smashup between large asteroids. This type of collision can eventually lead to the formation of planets.
Planets form by dribs and drabs within dusty disks around newly-forming stars. Dust sticks to dust to form small clumps. The clumps grow bigger as they which sweep up more material within the cloud until they’re boulder-sized. Gravity now works its wonders, drawing smaller bits of debris to larger until asteroids (also called planetesimals), the seeds of the planets form.
Many asteroids break apart when they collide, but others continue to grow by accumulation until they’ve collected enough stuff to collapse through self-gravity to form a sphere. After 100 million years of bone-crushing impacts, a planet is born!
Astronomers had been regularly observing the star NGC 2547-ID8 located 1,200 light years away in the constellation Vela the Sails with the Spitzer telescope, which can see into the infrared, a color of light just beyond the red end of the rainbow spectrum. We sense infrared as heat, but Spitzer sees it as glowing radiation.
Dust warmed by starlight radiates brightly in the infrared. Previous observations of NGC 2547-ID8 had already shown variations in the amount of dust around the star, hinting at possible asteroid collisions. But astronomers couldn’t believe their eyes when they compared photos made in August 2012 and five months later in January 2013.
“We not only witnessed what appears to be the wreckage of a huge smashup, but have been able to track how it is changing – the signal is fading as the cloud destroys itself by grinding its grains down so they escape from the star,” said Kate Su of the University of Arizona and co-author on the study.
Now a large, thick cloud of dust orbits the star which the team of astronomers is keeping their eye on in hopes of spotting more collisions.
“We are watching rocky planet formation happen right in front of us,” said George Rieke, a University of Arizona co-author of the new study. Although no one was around to watch out solar system’s planets form, Spitzer offers a glimpse into those lost times through its study of young, dust-cloaked stars in the present.