A pair of forward and reverse slow‐mode shocks detected by Ulysses at ∼5 AU
A pair of forward and reverse slow‐mode shocks detected by Ulysses at ∼5 AU
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DOI：
10.1029/98gl02014
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发表时间：
1998-05
影响因子：
5.2
通讯作者：
C. Ho;B. Tsurutani;N. Lin;L. Lanzerotti;Edward J. Smith;Bruce E. Goldstein;B. Buti;G. Lakhina;X. Y. Zhou
中科院分区：
文献类型：
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作者：
C. Ho;B. Tsurutani;N. Lin;L. Lanzerotti;Edward J. Smith;Bruce E. Goldstein;B. Buti;G. Lakhina;X. Y. Zhou
我们利用位于 5.3 个天文单位和 9°S 日光纬度的尤利西斯航天器的等离子体和磁场数据，报告了在遥远的日光层中首次发现的一对正向和反向慢模激波。慢模激波被发现发生在同向旋转相互作用区域（CIR）内的压缩磁场（低等离子体）区域。我们发现前向/反向慢速冲击的马赫数为 0.3-0.5。每次冲击时，太阳风速度都会跳跃至少 40 公里/秒。等离子体密度和离子温度的增加伴随着磁场的减小。还发现激波的速度为 60 km/s 和 115 km/s，厚度在 7.5‐12.6×104 km 之间（远大于离子惯性长度 ∼10³ km）。 Ulysses URAP 仪器在慢模式激波转变区域检测到低频等离子体波。然而，波的振幅不足以通过波粒相互作用提供足够的反常电阻率来消散冲击。还发现沿着局部磁场定向的低能（∼30-90 keV）电子增强与慢激波有关，表明激波具有加速行星际粒子的能力。这一发现意味着在日光层距离较远的 CIR 磁压缩区域（等离子体被挤出）中可能会发现更慢的激波。
We report the first finding of a pair of forward and reverse slow‐mode shocks in the distant heliosphere using plasma and magnetic field data from the Ulysses spacecraft located at 5.3 AU and 9°S heliolatitude. The slow‐mode shocks are found to occur in a compressed magnetic field (low plasma ) region within a co‐rotating interaction region (CIR). We find Mach numbers to be 0.3–0.5 with respect to forward/reverse slow shocks. Across each shock, the solar wind velocities jump by at least 40 km/s. The increases in plasma density and ion temperature accompany a decrease in the magnetic field. The shocks are also found to have velocities of 60 km/s and 115 km/s and thicknesses between 7.5‐12.6×104 km (much larger than the ion inertial length, ∼10³ km). Low frequency plasma waves are detected by the Ulysses URAP instrument at the slow‐mode shock transition regions. However, the waves are not of sufficient amplitude to provide enough anomalous resistivity through wave‐particle interactions for shock dissipation. Low energy (∼30–90 keV) electron enhancements directed along the local magnetic field are also found associated with the slow shocks, indicating the ability of the shocks to accelerate interplanetary particles. This finding imply that more slow shocks might be found in the CIR magnetic compressed regions (where plasma is squeezed out) at large heliospheric distances.