The Magnetic Response to Sudden Mass-loading of Comet 67P/Churyumov-Gerasimenko’s Induced Magnetosphere
Wednesday, 16 December 2015
Poster Hall (Moscone South)
On 6 June 2015 around 1500 UT there is a sudden increase in ion density and energy in the vicinity of 67P/CG, most likely from an outburst on the surface of the nucleus. The induced magnetosphere around 67P/CG reacts to this sudden mass loading: first there is an increase in the total magnetic field strength and an increase in fluctuations. Low frequency oscillations (f ≤ 10 mHz) are observed. In the early hours 0000 – 0400 UT of 7 June 2015 the plasma density returns to its pre-outburst value, and the magnetic field strength also returns, however the fluctuations in the magnetic field remain strong. Structures reminiscent of mirror mode waves- strong decreases in Bmag associated with strong Langmuir probe currents (proxy for density) – have also been detected starting at 2300 UTC 6 June and seem to evolve into structures with one steeper side. Wavelet analysis over the whole event shows that below 20 mHz there are several dominant frequencies, but different magnetic field components have different spectral content, implying strong polarization of the waves/oscillations.