AURORAL RADIO EMISSION FROM LATE L AND T DWARFS: A NEW CONSTRAINT ON DYNAMO THEORY IN THE SUBSTELLAR REGIME
AURORAL RADIO EMISSION FROM LATE L AND T DWARFS: A NEW CONSTRAINT ON DYNAMO THEORY IN THE SUBSTELLAR REGIME
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L 和 T 矮星晚期的极光射电发射：对恒星下动力理论的新约束
DOI：
--
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
D. Stevenson
中科院分区：
文献类型：
--
作者：
M. Kao;G. Hallinan;J. Pineda;I. Escala;A. Burgasser;S. Bourke;D. Stevenson
我们利用 Karl G. Jansky 甚大阵列 (VLA) 观测了六颗晚期 L 型和 T 型矮星，以研究与大规模极光流相关的高度圆偏振射电发射的存在。之前针对约 60 个 L6 或更高版本目标的调查仅产生了一次检测结果。我们的样本包括之前检测到的T6.5矮星2MASS 10475385+2124234，以及因存在Hα发射和/或光学红外光度变化而选择的五个新目标，这些是极光活动的可能表现。我们检测到 2MASS 10475385+2124234，以及有偏差样本中五个目标中的四个，包括强红外可变源 SIMP J01365662+0933473 和明亮的 Hα 发射器 2MASS 12373919+6526148，增强了这些不同波长的活动相关的可能性。无线电发射频率对应于每个矮星表面附近下限磁场强度的精确测定，这个新样本为低质量褐矮星体系中的发电机理论提供了强有力的约束。六个目标中的五个已确认磁场 ≳ 2.5 ?> kG。我们的结果提供了初步证据，表明在这种质量状态下运行的发电机可能与最近提出的模型的预测值不一致。在更高无线电频率下的进一步观察对于验证这一断言至关重要。
We have observed six 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 L6 or later targets have yielded only one detection. Our sample includes the previously detected T6.5 dwarf 2MASS 10475385+2124234, as well as five new targets selected for the presence of Hα emission and/or optical infrared photometric variability, which are possible manifestations of auroral activity. We detect 2MASS 10475385+2124234, as well as four of the five targets in our biased sample, including the strong IR-variable source SIMP J01365662+0933473 and bright Hα emitter 2MASS 12373919+6526148, reinforcing the possibility that activity at these disparate wavelengths is related. The radio emission frequency corresponds to a precise determination of the lower-bound magnetic field strength near the surface of each dwarf, and this new sample provides robust constraints on dynamo theory in the low-mass brown dwarf regime. Magnetic fields ≳ 2.5 ?> kG are confirmed for five of six targets. Our results provide tentative evidence that the dynamo operating in this mass regime may be inconsistent with predicted values from a recently proposed model. Further observations at higher radio frequencies are essential for verifying this assertion.
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影响因子：
64.8
作者：
G. Hallinan;S. P. Littlefair;G. Cotter;S. Bourke;L. K. Harding;J. Pineda;R. P. Butler;A. Golden;G. Basri;J. Doyle;M. Kao;S. Berdyugina;A. Kuznetsov;M. Rupen;A. Antonova
通讯作者：
G. Hallinan;S. P. Littlefair;G. Cotter;S. Bourke;L. K. Harding;J. Pineda;R. P. Butler;A. Golden;G. Basri;J. Doyle;M. Kao;S. Berdyugina;A. Kuznetsov;M. Rupen;A. Antonova
影响因子：
20.9
作者：
A. Reiners
通讯作者：
A. Reiners
解释全对流恒星中大尺度和小尺度磁场的共存
DOI：
10.1088/2041-8205/813/2/l31
发表时间：
2015
期刊：
The Astrophysical Journal Letters
影响因子：
--
作者：
Christensen
通讯作者：
Christensen
M 矮星中的分子塞曼效应建模：方法和初步结果
影响因子：
6.5
作者：
Shulyak;Reiners;Kochukhov;Piskunov;Seifahrt
通讯作者：
Seifahrt