Old images, new discovery

At the Observatory of Paris, Jean Guibert and Francoise Crifo dug up three old pictures of the newly discovered object, and found that it had moved considerably between 1975 and 1999 (see adjacent animation) indicating that the object is closer than other stars in the images.

Guibert and Crifo made the distance estimate of 13 light-years by relying on comparisons with objects that have similar characteristics. For that reason, the distance figure could change as more is learned about the object. The object was named DENIS-P J104814.7-395606.1 and will be reported in an upcoming issue of the journal Astronomy and Astrophysics Letters.

Brown dwarfs aren't massive enough to trigger the thermonuclear reactions that power real stars. But, most researchers say, they are more massive than planets.

Scientists are working to develop new classifications for different types of brown dwarfs. In addition there are also four other known "colors" of dwarfs, two of which are active stars:

White dwarfs: Burned-out stars that no longer shine through nuclear fusion, and have collapsed to Earth-sized objects. Their surface temperature rises as they collapse, making them white-hot.

Yellow dwarfs: Normal, active stars with our Sun's temperature and mass.

Red dwarfs: Active stars that are small, cooler and dimmer than our Sun. The cooler a star the redder it is, just as a dying ember fades from yellow-orange to cherry-red.

Black dwarfs: A theorized later stage of a white dwarfs that cools to nearly absolute zero. The universe isn't old enough yet for black dwarfs to exist, scientists say.