Scientists discover the oldest known circumstellar disk that can form stars

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circumstellar disk
An artist's conception of this unusual system, a red dwarf star surrounded by the oldest known circumstellar disk.

In a recent research project, a group of citizen scientists and professional astronomers work together 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. From the disk, planets can form as the material collides and aggregates.

The project was led by researchers from University of Oklahoma. The team described a newly identified red dwarf star with a warm circumstellar disk.

Circumstellar disks around red dwarfs are rare to begin with, but the star, called AWI0005x3s, appears to have sustained its disk for an exceptionally long time.

The findings are published in The Astrophysical Journal Letters.

Researchers suggest that most disks of this kind fade away in less than 30 million years.

This particular red dwarf is a candidate member of the Carina stellar association, which would make it around 45 million years old. It’s the oldest red dwarf system with a disk scientists have seen.

The discovery relied on citizen scientists from Disk Detective, a project led by NASA. It is designed to find new circumstellar disks.

At the project’s website, DiskDetective.org, users make classifications by viewing ten-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, it would be hard to spot this object. The WISE mission alone found 747 million [warm infrared] objects, and scientists expect a few thousand to be circumstellar disks.

Determining the age of a star can be tricky or impossible. But the Carina association, where this red dwarf was found, is a group of stars whose motions through the Galaxy indicate that they were all born at roughly the same time in the same stellar nursery.

Researchers suggest that it is surprising to see a circumstellar disk around a star that may be 45 million years old, because normally scientists expect these disks to dissipate within a few million years.

More observations will be needed to determine whether the star is really as old as researchers estimated. If it turns out to be, it will become a benchmark system to understand the lifetime of disks.

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News Source: Carnegie Institution for Science.
Figure legend: This Knowridge.com image is credited to Jonathan Holden/ Disk Detective.