A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the main sequence to planets
A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the main sequence to planets
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DOI：
10.1093/mnras/stab2168
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发表时间：
2021-07
期刊：
影响因子：
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通讯作者：
P. Leto;C. Trigilio;J. Krtička;L. Fossati;R. Ignace;M. Shultz;C. Buemi;L. Cerrigone;G. Umana-G.
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文献类型：
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作者：
P. Leto;C. Trigilio;J. Krtička;L. Fossati;R. Ignace;M. Shultz;C. Buemi;L. Cerrigone;G. Umana-G.
在本文中，我们对从早B型到早A型光谱的热磁星样本的非相干非热射电辐射进行了分析。这些恒星涵盖了广泛的恒星参数和风的特性，它们的射电辐射具有共性，这对最初设想的星风情景提出了新的挑战。人们曾认为，产生射电辐射的相对论电子源自星风打开磁力线时形成的电流片。然而，温度较低的恒星的实际质量损失率太小，无法解释观测到的非热宽带射电频谱。相反，我们认为在内部磁层内部存在一个类似于木星的辐射带。这样的结构解释了宽带射电辐射对星风质量损失率的总体不相关性。此外，通过将更大样本的磁星的射电光度与其恒星参数相关联，我们凭经验确定了自转和磁特性的综合作用。最后，我们的早型磁星样本表明，非热射电光度与磁层共转所感应的电压之间存在一种比例关系，这种关系似乎适用于具有偶极主导磁层的更广泛的恒星类型（如木星以及超冷矮星和褐矮星的情况）。我们得出结论，有序且稳定旋转的磁层在支持非热电子产生方面具有共同的物理机制。
In this paper, we present the analysis of incoherent non-thermal radio emission from a sample of hot magnetic stars, ranging from early-B to early-A spectral type. Spanning a wide range of stellar parameters and wind properties, these stars display a commonality in their radio emission which presents new challenges to the wind scenario as originally conceived. It was thought that relativistic electrons, responsible for the radio emission, originate in current sheets formed where the wind opens the magnetic field lines. However, the true massloss rates from the cooler stars are too small to explain the observed non-thermal broadband radio spectra. Instead, we suggest the existence of a radiation belt located inside the innermagnetosphere, similar to that of Jupiter. Such a structure explains the overall indifference of the broadband radio emissions on wind mass-loss rates. Further, correlating the radio luminosities from a larger sample of magnetic stars with their stellar parameters, the combined roles of rotation and magnetic properties have been empirically determined. Finally, our sample of early-type magnetic stars suggests a scaling relationship between the non-thermal radio luminosity and the electric voltage induced by the magnetosphere’s co-rotation, which appears to hold for a broader range of stellar types with dipole-dominated magnetospheres (like the cases of the planet Jupiter and the ultra-cool dwarf stars and brown dwarfs). We conclude that well-ordered and stable rotating magnetospheres share a common physical mechanism for supporting the generation of non-thermal electrons.