Oldest Known Planet-Forming Disk Discovered

A group of citizen scientists and professional astronomers, including Carnegie's Jonathan Gagné, joined forces to discover an unusual hunting ground for exoplanets. They found a star surrounded by the oldest known circumstellar disk: a primordial ring of gas and dust that orbits around a young star and from which planets can form as the material collides and aggregates.

Led by Steven Silverberg of the University of Oklahoma, the team described a newly identified red dwarf star with a warm circumstellar disk of the kind associated with young planetary systems. Circumstellar disks around red dwarfs like this one are rare to begin with, but this star, called AWI0005x3s, appears to have sustained its disk for an exceptionally long time. The findings are published by The Astrophysical Journal Letters.

"Most disks of this kind fade away in less than 30 million years," said Silverberg. "This particular red dwarf is a candidate member of the Carina stellar association, which would make it around 45 million years old [like the rest of the stars in that group]. It's the oldest red dwarf system with a disk we've seen in one of these associations."

The discovery relied on citizen scientists from Disk Detective, a project led by NASA/GSFC's Dr. Marc Kuchner that is designed to find new circumstellar disks. At the project's website, DiskDetective.org, users make classifications by viewing 10-second videos of data from NASA surveys, including the Wide-field Infrared Survey Explorer mission (WISE) and Two-Micron All Sky Survey (2MASS) projects. Since the launch of the website in January 2014, roughly 30,000 citizen scientists have participated in this process, performing roughly 2 million classifications of celestial objects.

"Without the help of the citizen scientists examining these objects and finding the good ones, we might never have spotted this object," Kuchner said. "The WISE mission alone found 747 million [warm infrared] objects, of which we expect a few thousand to be circumstellar disks."