Astronomers weigh the coldest brown dwarfs with astronomy's sharpest eyes

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Infrared image of the dusty brown dwarf binary HD 130948BC. The binary is seen in the upper left and has a total mass about 11 percent the mass of the sun. The binary is in orbit around a young sun-like star, seen to the lower right. This image was obtained with the adaptive optics system on the Keck II Telescope, located on Mauna Kea, Hawaii. The image is 3.75 arc seconds on a side (about 1/500 the size of the moon), and the binary's separation is about 0.1 arc seconds. Credit: Mr. Trent Dupuy and Dr. Michael Liu (Institute for Astronomy, University of Hawaii).

Astronomers have used ultrasharp images obtained with the Keck Telescope and Hubble Space Telescope to determine for the first time the masses of the coldest class of "failed stars," a.k.a. brown dwarfs. With masses as light as 3 percent the mass of the sun, these are the lowest mass free-floating objects ever weighed outside the solar system. The observations are a major step in testing the theoretical predictions of objects that cannot generate their own internal energy, both brown dwarfs and gas-giant planets. The new findings, which are being presented in a press conference today at the American Astronomical Society meeting in St. Louis, show that the predictions may have some problems.

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All News summaries for June 02, 2008