Astronomers spot fun-sized solar system

Seriously dinky

By Lucy Sherriff • Get more from this author

Posted in Science, 9th February 2005 15:37 GMT

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Astronomers working on data from NASA's Spitzer telescope have spotted a disk of planet-forming material in orbit around a brown dwarf - a failed star just 15 times the size of Jupiter.

This is the smallest potential solar system ever seen, and could help scientists understand more about how planetary systems form. It also raises the possibility that the universe could be littered with planetary systems orbiting bodies barely bigger than planets themselves.

A NASA artist's impression of a miniature solar system

Dr Kevin Luhman and his colleagues at the Gemini observatory in Hawaii first discovered the brown dwarf, OTS 44, about six months ago. Luhman is an astronomer at the Harvard Smithsonian Center for Astrophysics and lead author of the new study.

It lies 500 light years away, in the Chameleon constellation. Once it had been identified, Spitzer's infrared instruments were used to get a closer look, and the dusty disk was revealed. Longer searches with Spitzer could even reveal disks around brown dwarfs below 10 Jupiter masses, the scientists say.

Luhman said: "There may be a host of miniature solar systems out there, in which planets orbit brown dwarfs. This leads to all sorts of new questions, like 'Could life exist on such planets?' or 'What do you call a planet circling a planet-sized body? A moon or a planet?'"

Disks like the one found circling OTS 44 have been found around brown dwarves with masses of roughly 25 times that of Jupiter before, but never around such a small one. Astronomers think there is enough material around OTS 44 to form several rocky, Earth-sized planets and a small gas giant.

Dr Giovanni Fazio, a colleague of Luhman's at the Harvard Smithsonian, commented: "In this case, we are seeing the ingredients for planets around a brown dwarf near the dividing line between planets and stars. This raises the tantalizing possibility of planet formation around objects that themselves have planetary masses." ®