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Periodic radio bursts from very low mass stars and brown dwarfs simultaneously probe their magnetic and rotational properties. The brown dwarf 2MASSI J1047539+212423 (2M 1047+21) is currently the only T dwarf (T6.5) detected at radio…

Solar and Stellar Astrophysics · Physics 2015-08-05 P. K. G. Williams , E. Berger

We have observed 6 late-L and T dwarfs with the Karl G. Jansky Very Large Array (VLA) to investigate the presence of highly circularly polarized radio emission, associated with large-scale auroral currents. Previous surveys encompassing ~60…

Solar and Stellar Astrophysics · Physics 2016-02-17 Melodie M. Kao , Gregg Hallinan , J. Sebastian Pineda , Ivanna Escala , Adam Burgasser , Stephen Bourke , David Stevenson

We present multi-epoch radio and optical observations of the M7 dwarf 2MASS J13142039+1320011. We detect a ~1 mJy source at 1.43, 4.86, 8.46 and 22.5 GHz, making it the most luminous radio emission over the widest frequency range detected…

Solar and Stellar Astrophysics · Physics 2015-05-28 M. McLean , E. Berger , J. Irwin , J. Forbrich , A. Reiners

We report the first direct detection of a strong, 5 kG magnetic field on the surface of an active brown dwarf. LSR J1835+3259 is an M8.5 dwarf exhibiting transient radio and optical emission bursts modulated by fast rotation. We have…

Solar and Stellar Astrophysics · Physics 2017-10-04 S. V. Berdyugina , D. M. Harrington , O. Kuzmychov , J. R. Kuhn , G. Hallinan , A. F. Kowalski , S. L. Hawley

We present the first simultaneous, multi-wavelength observations of an L dwarf, the L3.5 candidate brown dwarf 2MASS J00361617+1821104, conducted with the Very Large Array, the Chandra X-ray Observatory, and the Kitt Peak 4-m telescope. We…

[Abridged] We present an 8.5-hour simultaneous radio, X-ray, UV, and optical observation of the L dwarf binary 2MASSW J0746+20. We detect strong radio emission, dominated by short-duration periodic pulses at 4.86 GHz with P=124.32+/-0.11…

Brown dwarfs display Jupiter-like auroral phenomena such as magnetospheric H$\alpha$ emission and coherent radio emission. Coherent radio emission is a probe of magnetospheric acceleration mechanisms and provides a direct measurement of the…

Solar and Stellar Astrophysics · Physics 2023-07-12 H. K. Vedantham , Trent J. Dupuy , E. L. Evans , A. Sanghi , J. R. Callingham , T. W. Shimwell , W. M. J. Best , M. C. Liu , P. Zarka

We present radio observations of a comprehensive sample of 90 dwarf stars and brown dwarfs ranging from spectral type M5 to T8. We detect three radio active sources in addition to the six objects previously detected in quiescence and…

Astrophysics · Physics 2008-11-26 Edo Berger

With the improvements in radio interferometry sensitivity, the quest for coherent radio emission from exoplanets and ultra-cool dwarfs, which is indicative of their magnetic fields, has gained significant momentum in recent years. We…

In this paper we simulate the cyclic circularly-polarised pulses of the ultra-cool dwarf TVLM513-46546, observed with the VLA at 4.88 and 8.44 GHz on May 2006, by using a 3D model of the auroral radio emission from the stellar…

Solar and Stellar Astrophysics · Physics 2017-06-21 P. Leto , C. Trigilio , C. S. Buemi , G. Umana , A. Ingallinera , L. Cerrigone

We present the detection of rotationally modulated, circularly polarized radio emission from the T8 brown dwarf WISE J062309.94-045624.6 between 0.9 and 2.0 GHz. We detected this high proper motion ultracool dwarf with the Australian SKA…

M dwarfs are the most abundant stars in the Galaxy and exhibit diverse magnetic behaviours. Understanding their large-scale magnetic fields is essential to study stellar dynamos and assess the impact of magnetic activity on planetary…

We present the detection of 2MASS J22282889-4310262 (2M2228), a T6/T6.5 brown dwarf, using the Karl G. Jansky Very Large Array (VLA) archival data observed at C band (4-8 GHz) over two observing epochs ($2\times96$ minutes). 2M2228 is…

We report on radio observations of the M8.5 dwarf LSR J1835+3259 and the L3.5 dwarf 2MASS J00361617+1821104, which provide the strongest evidence to date that the electron cyclotron maser instability is the dominant mechanism producing…

Astrophysics · Physics 2009-11-13 G. Hallinan , A. Antonova , J. G. Doyle , S. Bourke , C. Lane , A. Golden

A fraction of very low mass stars and brown dwarfs are known to be radio active, in some cases producing periodic pulses. Extensive studies of two such objects have also revealed optical periodic variability and the nature of this…

Solar and Stellar Astrophysics · Physics 2015-06-17 Leon K. Harding , Gregg Hallinan , Richard P. Boyle , Aaron Golden , Navtej Singh , Brendan Sheehan , Robert T. Zavala , Ray F. Butler

Radio activity has been observed in a large variety of stellar objects, including in the last few years, ultra-cool dwarfs. To explore the extent of long-term radio activity in ultra-cool dwarfs, we use data taken over an extended period of…

Astrophysics · Physics 2009-11-13 A. Antonova , J. G. Doyle , G. Hallinan , A. Golden , C. Koen

We present paper six of the NIRSPEC Brown Dwarf Spectroscopic Survey, an analysis of multi-epoch, high-resolution (R~20,000) spectra of 25 field dwarf systems (3 late-type M dwarfs, 16 L dwarfs, and 6 T dwarfs) taken with the NIRSPEC…

Solar and Stellar Astrophysics · Physics 2015-08-06 L. Prato , G. N. Mace , E. L. Rice , I. S. McLean , J. D. Kirkpatrick , A. J. Burgasser , S. S. Kim

We present new results from a continuing 5 GHz search for flaring radio emission from a sample of L and T brown dwarfs, conducted with the 305-m Arecibo radio telescope. In addition to the previously reported flaring from the T6.5-dwarf…

Solar and Stellar Astrophysics · Physics 2016-04-18 Matthew Route , Alexander Wolszczan

*Abbreviated abstract* Context: Brown dwarfs in the spectral range L9-T3.5, within the so called L/T transition, have been shown to be variable at higher amplitudes and with greater frequency than other field dwarfs. [...] Now, more…

Earth and Planetary Astrophysics · Physics 2019-11-04 Simon C. Eriksson , Markus Janson , Per Calissendorff

We wish to clarify whether strong magnetic fields can be effectively generated in typically low-mass dwarf galaxies and to assess the role of dwarf galaxies in the magnetization of the Universe. We performed a search for radio emission and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Krzysztof T. Chyzy , Marek Wezgowiec , Rainer Beck , Dominik J. Bomans
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