This artist’s illustration shows a planetary disk (left) that weighs the equivalent of 50 Jupiter-mass planets. It demonstrates a first-of-its-kind feat from astronomers using the Herschel space observatory. The scientists were able to weigh the planet-forming contents swirling around a young star with the most precision yet. CREDIT: NASA/JPL-Caltech

Star Not Too Old to Have Planets After All

by Charles Q. Choi, Contributor
Date: 30 January 2013 Time: 01:01 PM ET

Disks of matter thought to be too old to serve as planetary nurseries may still be capable of forming worlds, surprised researchers announced today (Jan. 30).

“This will lead to new ideas in planet formation theories,” study lead author Edwin Bergin, an astrochemist at the University of Michigan at Ann Arbor, told

Scientists analyzed TW Hydrae, a star 176 light-years from Earth in the constellation Hydra. TW Hydrae, which has about the same mass as the sun, is surrounded by a dense ring of gas and dust. Such circumstellar rings are often protoplanetary disks, in which matter can clump to form larger rocks and eventually worlds. Since TW Hydrae is 2 1/2 times closer to Earth than the next nearest such star, astronomers studying planet formation have depended on TW Hydrae much as biologists do on lab mice, using it to help build computer models.

However, TW Hydrae itself was considered past its planet-forming years. Its circumstellar disk is estimated to between 3 million and 10 million years old, and most protoplanetary disks are thought to last only 2 million to 3 million years.

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