Astronomers from Berkeley and San Francisco State report the first confirmed sighting of a brown dwarf--a dim red object somewhere in mass between a large planet and a small star. Brown dwarfs have been the subject of a search as possible components of the dark matter supposedly permeating the universe.
Surprisingly, observations of the brown dwarf, located in the Pleiades star cluster, indicate that the cluster and probably all young star clusters within the Milky Way Galaxy are much older than previously thought.
"The ages of all young and intermediate clusters have been underestimated by as much as a factor of two," said team leader Gibor Basri, professor of astronomy. Basri, Geoffrey Marcy, professor of physics and astronomy at San Francisco State and a visiting scholar here, and James R. Graham, associate professor of astronomy here, reported their findings at a meeting of the American Astronomical Society this summer. Most light emitted by brown dwarfs comes from gravitational contraction, in the same way the planet Jupiter emits heat as it contracts. Jupiter, in fact, could be considered a very low mass brown dwarf, Marcy said. The discovery indicates objects in the substellar realm do actually exist, the astronomers say.