Possible planet lurks in disk surrounding distant star

June 13, 2013 at 5:25 PM
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LARAMIE, Wyo., June 13 (UPI) -- A planet could be tucked away in a gap in the disk surrounding a star 176 light-years from Earth, a University of Wyoming professor said.

While the origin of the gap is unclear, Hannah Jang-Condell, an assistant professor of physics and astronomy, said the research team's calculations indicate "that the gap may be harboring a planet of six-to-28 times the mass of the Earth," the university said in a release.

"That's a small planet," Jang-Condell said. It's not a 'gas giant.'"

Jang-Condell is a co-author of the paper, "The 0.5-2.22um Scattered Light Spectrum of the Disk Around TW Hydrae: Detection of a Partially Filled Disk Gap at 80 AU," published in The Astrophysical Journal.

Because the possible planet is approximately 7.5 billion miles from the TW Hydrae star and its heat source, she said, the mass probably has a temperature similar to Neptune's -- about minus 360 degrees Fahrenheit.

The disk lacks large dust grains in its outer regions, said John Debes, an astronomer from the Space Telescope Science Institute at Johns Hopkins University and lead author of the study.

"Typically, you need pebbles before you can form a planet," Debes said. "So, if there is a planet there and there is not even millimeter-sized dust ... farther out, the observation is inconsistent with traditional planet formation models."

An alternative planet-formation theory suggests a portion of the disk becomes unstable and collapses, causing a planet to form in just a few thousand years, he said.

"If we can actually confirm that there's a planet there, we can connect its characteristics to measurements of the gap properties," Debes says. "That might add to planet formation theories as to how you can actually form a planet very far out."

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