Also see the archival list of Science's Compass: Enhanced Perspectives
ASTRONOMY:
Enhanced: Brown Dwarfs
John E. Gizis
Since the discovery of brown dwarfs in 1995, hundreds have been detected in different astronomic environments. In his Perspective, Gizis reviews the current knowledge about these "failed stars," which are too light to sustain nuclear fusion. It is intriguing that the lightest brown dwarfs may be lighter than the heaviest planets. Gizis argues that the two classes of objects should nevertheless have different statistical properties, which should allow them to be distinguished.
The author is in the Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA. E-mail: gizis{at}udel.edu