Radio Pulsations from Ultracool Dwarfs
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Radio Pulsations from Ultracool Dwarfs

June 29, 2010
Radio Pulsations from Ultracool Dwarfs An artist's impression of the "super-aurorae" present at the magnetic poles of these radio emitting dwarfs which are responsible for the radio pulsations. More about this ImageBrown dwarfs occupy the mass gap between planets and stars and are thought to be one of the most populous objects in our Galaxy. They have a mass below that necessary to maintain hydrogen-burning nuclear fusion reactions in their cores and are therefore much cooler and dimmer than main sequence stars. This makes them very difficult to detect and, although astronomers have known of their existence for decades, it wasn't until 1995 that a brown dwarf was finally found. In recent years it has been discovered that these brown dwarfs can be extremely bright sources of radio emission. Up until now, it has been unclear how these failed stars can produce such high levels of this nature of radiation. Initially, it was assumed that it was the same kind of radio emission as that detected from stars such as our Sun. For such stars, the radio emission is produced by high energy electrons in the star's corona which are trapped spiralling in the star's magnetic field. These discoveries were made using the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities Inc. (Date of Image: April 2007)

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