ScienceDaily (Dec. 23, 2009) — Two brown dwarf-sized objects orbiting a giant old star show that planets may assemble around stars more quickly and efficiently than anyone thought possible, according to an international team of astronomers.

Artist's rendition of a brown dwarf and its moon orbiting a triple star system. (Credit: NASA)

"We have found two brown dwarf-sized masses around an ordinary star, which is very rare," said Alex Wolszczan, Evan Pugh professor of astronomy and astrophysics, Penn State and lead scientist on the project.

The star, BD +20 2457, is a K2 giant — an old bloated star nearing the end of its life. Seeing a pair of brown dwarfs around a K-type giant is a first for astronomers and offers a unique window into how they can be produced. The researchers from the ToruĊ„ Center for Astronomy, Poland and the Center for Exoplanets and Habitable Worlds, Penn State report their findings in the current issue of the Astrophysical Journal.

Brown dwarfs are dim, elusive objects that straddle the dividing line between planets and stars. They are too massive to be planets, but not massive enough to generate the fusion-powered energy of a star. These stellar cousins represent a kind of "missing link" between planets and stars, but little is known about how they are made.

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