First detection of a diamagnetic cavity at comet 67P/Churyumov-Gerasimenko
First detection of a diamagnetic cavity at comet 67P/Churyumov-Gerasimenko
复制标题
首次在 67P/Churyumov-Gerasimenko 彗星上发现反磁性空腔
DOI：
10.1051/0004-6361/201527728
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发表时间：
2016
影响因子：
6.5
通讯作者：
K. Glassmeier
中科院分区：
文献类型：
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作者：
C. Goetz;C. Koenders;I. Richter;K. Altwegg;J. Burch;C. Carr;E. Cupido;A. Eriksson;C. Güttler;P. Henri;P. Mokashi;Z. Németh;H. Nilsson;M. Rubin;H. Sierks;B. Tsurutani;Charlotte Vallat;M. Volwerk;K. Glassmeier
罗塞塔磁强计RPC-MAG自2014年8月以来一直在探索彗星67 P/Churyumov-Gerasimenko的等离子体环境。最初几个月主要是低频波，这些波演变成更复杂的特征。然而，在2015年7月底，接近近日点时，磁力计检测到一个根本不包含任何磁场的区域。
目的：这些特征与1986年在1 P/Halley彗星上观察到的反磁性空腔的外观相吻合。这里的空腔比以前模型预测的更长，并且具有不寻常的磁场配置，这需要解释
方法：详细分析机载磁力仪数据，并利用其估算放气速率。最小方差分析用于确定边界法线。
结果我们对罗塞塔等离子体联盟仪器获得的数据的分析证实了抗磁腔的存在。然而，它的大小比模拟预测的要大。一个可能的解释是不稳定性，传播沿着腔边界和可能的低磁压力的太阳风。这一结论得到了磁场指向太阳分量符号变化的支持。证据还表明，空洞边界以230 - 500 m/s的速度移动。
Context: The Rosetta magnetometer RPC-MAG has been exploring the plasma environment of comet 67P/Churyumov-Gerasimenko since August 2014. The first months were dominated by low-frequency waves which evolved into more complex features. However, at the end of July 2015, close to perihelion, the magnetometer detected a region that did not contain any magnetic field at all.
Aims: These signatures match the appearance of a diamagnetic cavity as was observed at comet 1P/Halley in 1986. The cavity here is more extended than previously predicted by models and features unusual magnetic field configurations, which need to be explained
Methods: The onboard magnetometer data were analyzed in detail and used to estimate the outgassing rate. A minimum variance analysis was used to determine boundary normals.
Results. Our analysis of the data acquired by the Rosetta Plasma Consortium instrumentation confirms the existence of a diamagnetic cavity. The size is larger than predicted by simulations, however. One possible explanation are instabilities that are propagating along the cavity boundary and possibly a low magnetic pressure in the solar wind. This conclusion is supported by a change in sign of the Sun-pointing component of the magnetic field. Evidence also indicates that the cavity boundary is moving with variable velocities ranging from 230−500 m/s.