Based on the observations by the Parker Solar Probe (PSP) during its encounter phases of approaching the Sun, I. C. Jebaraj et al. found that fundamental–harmonic (F-H) pairs constitute a majority of interplanetary (IP) type III radio bursts. In the present Letter, spectral characteristics of the IP F-H pairs are identified and analyzed further. The observations were made with the Radio Frequency Spectrometer (RFS) experiment on the PSP spacecraft in its encounter phase from the first to the ninth orbit as it traveled from 0.17 to 0.074 au from the Sun. The result shows that the occurrence rate of F-H pairs rises significantly with the rise in the number of IP type III radio bursts detected by the PSP or the enhancement in the time resolution of the RFS instrument. In particular, we compare the relationship between F and H spectral characteristics, such as the frequency-drift rate, emission intensity, relative bandwidth, duration, and fine structure. The results will be helpful for us to understand the physics underlying the generation and evolution of the IP F-H pairs as well as other IP type III radio bursts.

中文翻译：

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PSP 观测到的行星际 III 型射电暴基波-谐波对的频谱特性


根据帕克太阳探测器 （PSP） 在接近太阳的相遇阶段的观测，I. C. Jebaraj 等人发现基谐 （F-H） 对构成了行星际 （IP） III 型射电暴的大部分。在本信中，确定并进一步分析了 IP F-H 对的光谱特性。这些观测是在 PSP 航天器从第一轨道到第九轨道的相遇阶段进行的，当时它距离太阳从 0.17 到 0.074 天文单位。结果表明，随着 PSP 检测到的 IP III 型射电暴数量的增加或 RFS 仪器时间分辨率的提高，F-H 对的出现率显著上升。特别是，我们比较了 F 和 H 光谱特性之间的关系，例如频率漂移率、发射强度、相对带宽、持续时间和精细结构。这些结果将有助于我们了解 IP F-H 对以及其他 IP III 型射电暴产生和演变的物理学基础。