Anisotropic emission from comets: Fans versus jets. 1: Concept and modeling
Anisotropic emission from comets: Fans versus jets. 1: Concept and modeling
复制标题
彗星的各向异性发射：风扇与喷射。
DOI：
--
复制
发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Z. Sekanina
中科院分区：
文献类型：
--
作者：
Z. Sekanina
研究了彗星核太阳照射面离散发射源喷出的尘埃喷流和尘埃扇。这些特征的计算机生成图像说明了模式的多样性，可以通过改变自旋轴的位置、旋转周期、活动区的位置和范围以及给定太阳-地球-彗星几何形状的喷出物动力学常数来解释。结果表明，辐射扇是由高纬源绕具有相对高磁率的核自旋轴旋转产生的，但辐射扇的形成对旋转周期不敏感。看来至少对于近日点在地球轨道之外的彗星来说，风扇观测轴的位置角实际上与自旋轴的投影方向一致，从而限制了后者的空间方向。
Jets and fans of dust ejected from discrete emission sources on the sunlit side of comet nuclei were studied. Computer-generated images of these features illustrate the diversity of patterns that can be explained by varying the position of the spin axis, rotation period, location and extent of the active area, and the ejecta's dynamical constants for a given Sun-Earth-comet geometry. It is shown that an emission fan is generated by rotation of a high-latitude source about the spin axis of the nucleus with a relatively high obliquity, but that the fan's formation is rather insensitive to the rotation period. It appears that at least for comets with perihelia well outside the Earth's orbit, the position angle of a fan's observed axis virtually coincides with the projected direction of the spin axis, thus constraining the spatial orientation of the latter.