An update to a Saturnian longitude system based on kilometric radio emissions
An update to a Saturnian longitude system based on kilometric radio emissions
复制标题
基于公里无线电发射的土星经度系统更新
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
A. Lecacheux
中科院分区：
文献类型：
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作者：
W. Kurth;T. Averkamp;D. Gurnett;J. Groene;A. Lecacheux
[1] 由 Voyager 确定的土星千米辐射调制周期构成了国际天文学联合会认可的经度系统 (SLS) 的基础。然而，尤利西斯号和卡西尼号的观测表明，这个调制周期在几年的时间尺度上变化了百分之一的数量级，因此并不代表行星的内自转周期。一个新的经度系统是基于卡西尼号对千米射电发射的~2年观测而提出的，并解释了从2004年001天到2006年240天的时间间隔内有效的可变射电周期（SLS2）。该经度系统的早期使用揭示了许多似乎与射电周期锁定的磁层现象，例如外部磁场的变化、内磁层中的等离子体密度以及增强的磁层现象。高能离子的强度。自新系统提出以来对无线电发射的分析表明，无线电周期不断演变，甚至有时会出现第二个更短的周期。土星千米无线电发射峰值的太阳下经度几乎在上一个分析间隔之后立即开始偏离 SLS2 系统给出的经度。在这里，我们提供了 SLS3 的定义，它是基于可变周期无线电发射的经度系统的扩展，在 2004 年 001 天到 2007 年 222 天的间隔内有效。
[1] The period of Saturn kilometric radiation modulation as determined by Voyager forms the basis for a longitude system (SLS) recognized by the International Astronomical Union. However, Ulysses and Cassini observations have shown that this modulation period varies by the order of one percent on timescales of a few years and, hence, does not represent the internal rotation period of the planet. A new longitude system was proposed based on ∼2 years of Cassini observations of the kilometric radio emissions and accounts for the variable radio period (SLS2) valid over the time interval from day 001, 2004 through day 240, 2006. Early uses of this longitude system have revealed a number of magnetospheric phenomena which appear to be locked to the radio period, such as variations in the external magnetic field, the plasma density in the inner magnetosphere, and enhanced intensities of energetic ions. Analysis of the radio emissions since the new system was proposed revealed that the radio period continued to evolve, even showing a second, shorter period at times. The subsolar longitude of the peak of Saturn kilometric radio emissions begins to deviate from that given by the SLS2 system almost immediately after the previous analysis interval. Here, we provide a definition for SLS3, an extension to the longitude system valid over the interval from day 001, 2004 through day 222, 2007 based on variable period radio emissions.