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Discovery of radio emission from the brown dwarf LP944-20

Berger, E. and Ball, S. and Becker, K. M. and Clarke, M. and Frall, D. A. and Fukuda, T. A. and Hoffman, I. M. and Mellon, R. and Momjian, E. and Murphy, N. W. and Teng, S. H. and Woodruff, T. and Zauderer, B. A. and Zavala, R. T. (2001) Discovery of radio emission from the brown dwarf LP944-20. Nature, 410 (6826). p. 338. ISSN 0028-0836. doi:10.1038/35066514.

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Brown dwarfs are not massive enough to sustain thermonuclear fusion of hydrogen at their centres, but are distinguished from gas-giant planets by their ability to burn deuterium. Brown dwarfs older than ~ 10 Myr are expected to possess short-lived magnetic fields and to emit radio and X-rays only very weakly from their coronae. An X-ray flare was recently detected on the brown dwarf LP944-20, whereas previous searches for optical activity (and one X-ray search) yielded negative results. Here we report the discovery of quiescent and flaring radio emission from LP944-20, with luminosities several orders of magnitude larger than predicted by the empirical relation, between the X-ray and radio luminosities that has been found for many types of stars. Interpreting the radio data within the context of synchrotron emission, we show that LP944-20 has an unusually weak magnetic field in comparison to active M-dwarf stars, which might explain the previous null optical and X-ray results, as well as the strength of the radio emissions compared to those at X-ray wavelengths.

Item Type:Article
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URLURL TypeDescription ReadCube access
Berger, E.0000-0002-9392-9681
Momjian, E.0000-0003-3168-5922
Zauderer, B. A.0000-0003-1152-518X
Additional Information:© 2001 Macmillan Magazines Ltd. Received 26 October 2000; Accepted 18 January 2001. We thank B. Clark for the allocation of ad hoc VLA time. We also thank S. R. Kulkarni, D. E. Gary and R. Sari for helpful discussions. The initial observation of LP944-20 was undertaken as part of the National Radio Astronomy Observatory (NRAO) VLA Summer Program funded by the National Science Foundation (NSF). The National Radio Astronomy Observatory is a facility of the NSF operated under cooperative agreement by Associated Universities, Inc.
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Associated Universities Inc.UNSPECIFIED
Issue or Number:6826
Record Number:CaltechAUTHORS:20150331-070610485
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Official Citation:Discovery of radio emission from the brown dwarf LP944-20 p338 E. Berger, S. Ball, K. M. Becker, M. Clarke, D. A. Frail, T. A. Fukuda, I. M. Hoffman, R. Mellon, E. Momjian, N. W. Murphy, S. H. Teng, T. Woodruff, B. A. Zauderer and R. T. Zavala doi:10.1038/35066514
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:56224
Deposited By: Ruth Sustaita
Deposited On:31 Mar 2015 16:13
Last Modified:10 Nov 2021 20:56

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