NASA's Spitzer Space Telescope has spotted a dusty disc of material around a very small "failed star" called a brown dwarf, raising the possibility that there may be miniature solar systems in which planets orbit objects not much larger than planets, scientists said Monday.

The brown dwarf (search) named OTS 44 is only about 15 times the mass of Jupiter, much smaller than any other brown dwarf known to be surrounded by a disc of planet-building material, said Kevin Luhman, lead author of a study by the Harvard-Smithsonian Center for Astrophysics (search) in Cambridge, Mass.

"The neat thing about this brown dwarf is that it's near the dividing line between what's considered brown dwarf masses and planetary masses," Luhman said in a teleconference from the meeting on planet formation and detection at the Aspen (Colo.) Winter Conference on Astrophysics.

"This raises the possibility that there could be out there in space, objects that have planetary masses ... that themselves have planetary companions around them," he said, noting that the objects could be as small as five times the mass of Jupiter.

Early in their lives, stars like the sun were surrounded by discs of material from which planets like Earth formed.

Brown dwarfs are star-like objects with masses less than one-tenth the mass of the sun, Luhman said. Although they probably formed in the same way as stars, brown dwarfs are not massive enough to ignite and don't shine. Mostly dark, they are sometimes called failed stars.

OTS 44, located about 500 light-years from Earth in the constellation Chamaeleon, was found last year by the researchers using the Gemini Observatory (search) in Chile. They then used Spitzer, an infrared telescope, to spot the glow of its disc.

Before the discovery, the smallest brown dwarf known to have such a disc was 25 to 30 times the mass of Jupiter.

"We have identified the smallest body that is known to have the building blocks around it for making planets," Luhman said.

Astronomer Giovanni Fazio, a study co-author from the Harvard-Smithsonian Center, said in a statement that the results raised a "tantalizing possibility" that planets may form around objects with planet-scale masses.

Fazio led the development of Spitzer's infrared array camera at NASA's Goddard Space Flight Center in Greenbelt, Md.

The research will be published in the Feb. 10th issue of The Astrophysical Journal Letters. Other authors include Paola D'Alessia of the Universidad Nacional Autonoma de Mexico, and Nuria Calvet, Lori Allen, Lee Hartmann, Thomas Megeath and Philip Myers of the Harvard-Smithsonian Center for Astrophysics.

Spitzer, a $670 million mission launched in August 2003, is managed by NASA's Jet Propulsion Laboratory in Pasadena, Calif. Science operations are conducted by the Spitzer Science Center at the California Institute of Technology.