Charged particle signatures of the diamagnetic cavity of comet 67P/Churyumov–Gerasimenko

One of the scientific objectives of the Rosetta mission is to investigate the diamagnetic cavity of comet 67P/Churyumov–Gerasimenko. We employed combined data of several instruments of the Rosetta Plasma Consortium (RPC) to identify and study diamagnetic cavity crossing events. Using electron data from the Ion Electron Sensor (IES) to complement the Magnetometer (MAG) data enabled us to work out a search criterion for the cavity crossing events based on a unique signature we identified in the electron spectrum. Although this search criterion is insufficient to find all the cavity events, we were able to find an abundance of more than one hundred cavity crossings in the data obtained in the summer of 2015. This unexpectedly high number of events allowed us to study their common features, as well as the shape and extent of the diamagnetic cavity in the terminator plane. The results suggest that in the summer of 2015 there was a cavity around comet 67P, which had a highly variable outer boundary. We present the effects of the diamagnetic cavity on the thermal and suprathermal electron and suprathermal ion content of the plasma, and also the probable mechanisms responsible for these charged particle signatures.

[1]  J. Lebreton,et al.  RPC observation of the development and evolution of plasma interaction boundaries at 67P/Churyumov-Gerasimenko , 2016 .

[2]  S. Fuselier,et al.  Statistical Analysis of Suprathermal Electron Drivers at 67P/Churyumov-Gerasimenko , 2016 .

[3]  N. Edberg,et al.  Suprathermal electrons near the nucleus of comet 67P/Churyumov‐Gerasimenko at 3 AU: Model comparisons with Rosetta data , 2016 .

[4]  Anders Eriksson,et al.  First detection of a diamagnetic cavity at comet 67P/Churyumov-Gerasimenko , 2016 .

[5]  I. Richter,et al.  Mass loading at 67P/Churyumov‐Gerasimenko: A case study , 2016, 1805.05587.

[6]  Pierre Rochette,et al.  The effect of hydrostatic pressure up to 1.61 GPa on the Morin transition of hematite‐bearing rocks: Implications for planetary crustal magnetization , 2015 .

[7]  E. Cupido,et al.  Evolution of the plasma environment of comet 67P from spacecraft potential measurements by the Rosetta Langmuir probe instrument , 2015 .

[8]  J. Lebreton,et al.  Evolution of the ion environment of comet 67P/Churyumov-Gerasimenko - Observations between 3.6 and 2.0 AU , 2015 .

[9]  T. Gombosi,et al.  Four‐fluid MHD simulations of the plasma and neutral gas environment of comet 67P/Churyumov‐Gerasimenko near perihelion , 2015 .

[10]  T. Gombosi,et al.  Modeled Interaction of Comet 67P/Churyumov-Gerasimenko with the Solar Wind Inside 2 AU , 2015 .

[11]  J. Lebreton,et al.  Spatial distribution of low‐energy plasma around comet 67P/CG from Rosetta measurements , 2015, 1608.06745.

[12]  Jean-Pierre Lebreton,et al.  Birth of a comet magnetosphere: A spring of water ions , 2015, Science.

[13]  T. Gombosi.  Physics of Cometary Magnetospheres , 2015 .

[14]  J. Lebreton,et al.  The Rosetta Ion and Electron Sensor (IES) measurement of the development of pickup ions from comet 67P/Churyumov‐Gerasimenko , 2014 .

[15]  K. Glassmeier,et al.  Deep Space 1 at comet 19P/Borrelly: Magnetic field and plasma observations , 2011 .

[16]  J. Lebreton,et al.  RPC-MIP: the Mutual Impedance Probe of the Rosetta Plasma Consortium , 2007 .

[17]  R. Lundin,et al.  RPC-IES: The Ion and Electron Sensor of the Rosetta Plasma Consortium , 2007 .

[18]  K. Glassmeier,et al.  RPC: The Rosetta Plasma Consortium , 2007 .

[19]  K. Glassmeier,et al.  The Rosetta Mission: Flying Towards the Origin of the Solar System , 2007 .

[20]  K. Glassmeier,et al.  RPC-MAG The Fluxgate Magnetometer in the ROSETTA Plasma Consortium , 2007 .

[21]  Tamas Gombosi,et al.  Physics of Mass Loaded Plasmas , 2000 .

[22]  W. Ip,et al.  Observations of a shock and a recombination layer at the contact surface of comet Halley , 1989 .

[23]  T. Cravens.  A magnetohydrodynamical model of the inner coma of comet Halley , 1989 .

[24]  R. Sagdeev,et al.  A new model of cometary ionospheres , 1987 .

[25]  W. I. Axford,et al.  The formation of a magnetic-field-free cavity at comet Halley , 1987, Nature.

[26]  K. Glassmeier,et al.  First results from the Giotto magnetometer experiment at comet Halley , 1986 .

[27]  R. Anderson,et al.  Comet Giacobini-Zinner: Plasma Description , 1986, Science.

[28]  T. Gombosi,et al.  Solar wind stagnation near comets , 1985 .

[29]  K. Glassmeier,et al.  Dynamical features and spatial structures of the plasma interaction region of 67P/Churyumov–Gerasimenko and the solar wind , 2015 .

[30]  T. Cravens.  THEORY AND OBSERVATIONS OF COMETARY IONOSPHERES , 1987 .