CME impact on comet 67P-Churyumov-GerasimenkoReportar como inadecuado

CME impact on comet 67P-Churyumov-Gerasimenko - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

1 Aalto University School of Electrical Engineering, Department of Signal Processing and Acoustics, Finland 2 IRF - Swedish Institute of Space Physics Uppsala 3 Space Science Division San Antonio 4 Imperial College London 5 Blackett Laboratory 6 IGEP - Institut für Geophysik und Extraterrestrische Physik Braunschweig 7 SwRI - Southwest Research Institute San Antonio 8 LPC2E - Laboratoire de Physique et Chimie de l-Environnement et de l-Espace 9 UTSA Department of Physics and Astronomy San Antonio 10 Department of Physics Oslo 11 Wigner Research Center for Physics Budapest 12 IWF - Space Research Institute of Austrian Academy of Sciences

Abstract : We present Rosetta observations from comet 67P-Churyumov-Gerasimenko during the impact of a coronal mass ejection CME. The CME impacted on 5-6 Oct 2015, when Rosetta was about 800 km from the comet nucleus, and 1.4 AU from the Sun. Upon impact, the plasma environment is compressed to the level that solar wind ions, not seen a few days earlier when at 1500 km, now reach Rosetta. In response to the compression, the flux of suprathermal electrons increases by a factor of 5-10 and the background magnetic field strength increases by a factor of ∼2.5. The plasma density increases by a factor of 10 and reaches 600 cm −3 , due to increased particle impact ionisation, charge exchange and the adiabatic compression of the plasma environment. We also observe unprecedentedly large magnetic field spikes at 800 km, reaching above 200 nT, which are interpreted as magnetic flux ropes. We suggest that these could possibly be formed by magnetic reconnection processes in the coma as the magnetic field across the CME changes polarity, or as a consequence of strong shears causing Kelvin-Helmholtz instabilities in the plasma flow. Due to the limited orbit of Rosetta, we are not able to observe if a tail disconnection occurs during the CME impact, which could be expected based on previous remote observations of other CME-comet interactions.

Keywords : Sun: coronal mass ejections CMEs solar wind comets: individual: 67P-Churyumov-Gerasimenko

Autor: Niklas J. T. Edberg - M. Alho - M. André - D. J. Andrews - E. Behar - J. L. Burch - M. Carr - E. Cupido - I. Engelhardt - I. Eri



Documentos relacionados