论文标题
磁性B型星Rho OPHC的极光无线电发射
The auroral radio emission of the magnetic B-type star rho OphC
论文作者
论文摘要
主要序列早期型恒星的非热无线电发射是恒星磁性的标志。我们提供了多波长（1.6-16.7 GHz）的ATCA测量早期磁性星Rho OPHC，这是一种平坦的非热线无线电源。 RHO OPHC无线电发射在陡峭的频谱依赖性中部分圆形极化：在最低频率亚带（1.6 GHz）下极化发射的比例约为60％，而在16.7 GHz处未检测到。这是Rho Ophc磁层的相干极光发射（为）的明确证据。有趣的是，Rho OphC的检测与特殊的旋转相无关。这是恒星几何形状的结果，它使扩增的辐射的强烈各向异性辐射束总是指向地球。圆极化标志的证据主要是电磁波的普通模式的扩增，这与密集区域内发生的maser扩增一致。这是极性帽的血浆蒸发蒸发的间接证据，极帽是导致热X射线极光的一种现象。 Rho Ophc并不是第一个以O-Mode为主导的早期型磁性星，但始终是第一颗恒星。
The non-thermal radio emission of main-sequence early-type stars is a signature of stellar magnetism. We present multi-wavelength (1.6-16.7 GHz) ATCA measurements of the early-type magnetic star rho OphC, which is a flat-spectrum non-thermal radio source. The rho OphC radio emission is partially circularly polarized with a steep spectral dependence: the fraction of polarized emission is about 60% at the lowest frequency sub-band (1.6 GHz) while is undetected at 16.7 GHz. This is clear evidence of coherent Auroral Radio Emission (ARE) from the rho OphC magnetosphere. Interestingly, the detection of the rho OphC's ARE is not related to a peculiar rotational phase. This is a consequence of the stellar geometry, which makes the strongly anisotropic radiation beam of the amplified radiation always pointed towards Earth. The circular polarization sign evidences mainly amplification of the ordinary mode of the electromagnetic wave, consistent with a maser amplification occurring within dense regions. This is indirect evidence of the plasma evaporation from the polar caps, a phenomenon responsible for the thermal X-ray aurorae. rho OphC is not the first early-type magnetic star showing the O-mode dominated ARE but is the first star with the ARE always on view.
