Wide-Band Spectroscopy of Two Radio Bursts on AD Leonis
Wide-Band Spectroscopy of Two Radio Bursts on AD Leonis
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AD Leonis 上两次射电爆发的宽带光谱
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
T. Bastian
中科院分区：
文献类型：
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作者：
R. Osten;T. Bastian
我们报告了狮子座星星AD的两个射电爆发的高时间分辨率宽带光谱观测。这些观测是由阿雷西博天文台的305米望远镜于2003年6月13日至14日获得的。使用宽带阿雷西博脉冲星处理器，这些观测采样了400 MHz的总带宽，分布在500 MHz的频率范围内，1120-1620 MHz，频率分辨率为0.78 MHz，时间分辨率为10 ms。（Δt ~ 30 ms），高亮度温度（Tb > 1014 K），高度圆偏振，快速漂移的射电子爆发，中值带宽Δ v/v ~ 5%。反向漂移率很小，并且具有对称分布（正和负频率漂移），高斯半高宽反向漂移率为4.5 × 10-4 s MHz-1。快速漂移的子爆发发生在13秒-1的平均速率，并没有表现出周期性复发的证据。狮子座AD上的快速漂移射电事件非常令人想起太阳分米波尖峰爆发。我们认为，发射是由于基本的等离子体辐射。6月14日记录的第二个高度圆极化的射电爆发具有明显不同的性质：平滑变化的强度分布，其特征是频率随时间的缓慢漂移（-52 MHz s-1）。在假设该源是由于扰动通过低日冕传播的情况下，推断源的大小为0.1-1 R，意味着亮温范围为6 × 1011-6 × 1013 K;这是相干射电爆发的另一个例子。
We report high time-resolution broadband spectroscopic observations of two radio bursts on the classical flare star AD Leonis. The observations were acquired by the 305 m telescope at Arecibo Observatory on 2003 June 13-14. Using the Wideband Arecibo Pulsar Processor, these observations sampled a total bandwidth of 400 MHz, distributed over a 500 MHz frequency range, 1120-1620 MHz, with a frequency resolution of 0.78 MHz and a time resolution of 10 ms. The radio burst observed on June 13 is characterized by the presence of multitudes of short-duration (Δt ~ 30 ms), high brightness temperature (Tb > 1014 K), highly circularly polarized, fast-drift radio sub-bursts, with median bandwidths Δν/ν ~ 5%. The inverse drift rates are small and have a symmetric distribution (both positive and negative frequency drifts), with a Gaussian FWHM inverse drift rate of 4.5 × 10-4 s MHz-1. The fast-drift sub-bursts occur at a mean rate of 13 s-1 and show no evidence for periodic recurrence. The fast-drift radio events on AD Leo are highly reminiscent of solar decimetric spike bursts. We suggest that the emission is due to fundamental plasma radiation. A second highly circularly polarized radio burst, recorded June 14, has markedly different properties: a smoothly varying intensity profile characterized by a slow drift in frequency with time (-52 MHz s-1). Under the assumption that the source is due to a disturbance propagating through the low corona, a source size of 0.1-1 R⋆ is inferred, implying a brightness temperature range 6 × 1011-6 × 1013 K; another example of a coherent radio burst.