Radio Constraints on Activity in Young Brown Dwarfs
We report on searches for radio emission from three of the nearest known young brown dwarfs using the Very Large Array. We have obtained sensitive upper limits on 3.6 cm emission from 2MASSW J1207334-393254, TWA 5B, and SSSPM J1102-3431, all of which are likely members of the 68 Myr old TW Hydrae as...
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Published in | The Astrophysical journal Vol. 644; no. 1; pp. L67 - L70 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
IOP Publishing
10.06.2006
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Online Access | Get full text |
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Summary: | We report on searches for radio emission from three of the nearest known young brown dwarfs using the Very Large Array. We have obtained sensitive upper limits on 3.6 cm emission from 2MASSW J1207334-393254, TWA 5B, and SSSPM J1102-3431, all of which are likely members of the 68 Myr old TW Hydrae association. We derive constraints on the magnetic field strength and the number density of accelerated electrons, under the assumption that young brown dwarf atmospheres are able to produce gyrosynchrotron emission, as seems to be indicated in older brown dwarfs. For the young brown dwarf TWA 5B, the ratio of its detected X-ray luminosity to the upper limit on radio luminosity places it within the expected range for young stars and older, active stars. Thus, its behavior is anomalous compared to older brown dwarfs, in which radio luminosity is substantially enhanced over the expected relationship. Our observations deepen the conundrum of magnetic activity in brown dwarfs and suggest that a factor other than age is more important for determining radio emission in cool substellar objects. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1 |
ISSN: | 1538-4357 0004-637X 1538-4357 |
DOI: | 10.1086/505328 |