Observations of high-plasma density region in the inner coma of 67P/Churyumov-Gerasimenko during early activity

被引：12

作者：

Yang, Lei ^{[1
]}

Paulsson, J. J. P. ^{[1
]}

Wedlund, C. Simon ^{[1
]}

Odelstad, E. ^{[2
]}

Edberg, N. J. T. ^{[2
]}

Koenders, C. ^{[3
]}

Eriksson, A. I. ^{[2
]}

Miloch, W. J. ^{[1
]}

机构：

[1] Univ Oslo, Dept Phys, Sem Soelands Vei 24,Postbox 1048, N-0317 Oslo, Norway

[2] Swedish Inst Space Phys, Lagerhyddsvagen 1, SE-75121 Uppsala, Sweden

[3] Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, Mendelssohnstr 3, D-38106 Braunschweig, Germany

来源：

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2016年 / 462卷

关键词：

plasmas; instrumentation: miscellaneous; methods: data analysis; comets: individual: 67P/C-G; SOLAR-WIND INTERACTION; LANGMUIR PROBE; ROSETTA ION; ENVIRONMENT; RPC; MAGNETOSPHERES; PREDICTIONS; MISSION; WAVES; RATES;

D O I：

10.1093/mnras/stw2046

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

In 2014 September, as Rosetta transitioned to close bound orbits at 30 km from comet 67P/Churyumov-Gerasimenko, the Rosetta Plasma Consortium Langmuir probe (RPC-LAP) data showed large systematic fluctuations in both the spacecraft potential and the collected currents. We analyse the potential bias sweeps from RPC-LAP, from which we extract three sets of parameters: (1) knee potential, that we relate to the spacecraft potential, (2) the ion attraction current, which is composed of the photoelectron emission current from the probe as well as contributions from local ions, secondary emission, and low-energy electrons, and (3) an electron current whose variation is, in turn, an estimate of the electron density variation. We study the evolution of these parameters between 4 and 3.2 au in heliocentric and cometocentric frames. We find on September 9 a transition into a high-density plasma region characterized by increased knee potential fluctuations and plasma currents to the probe. In conjunction with previous studies, the early cometary plasma can be seen as composed of two regions: an outer region characterized by solar wind plasma, and small quantities of pick-up ions, and an inner region with enhanced plasma densities. This conclusion is in agreement with other RPC instruments such as RPC-MAG, RPC-IES and RPC-ICA, and numerical simulations.

引用

页码：S33 / S44

页数：12

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