Evidence for Rayleigh-Taylor Plasma Instability at the Front of Solar Coronal Mass Ejections

Atmosphere

卷:10

Alessandro Bemporad¹  Daniele Telloni¹  Ester Antonucci¹  Francesco Carbone² 

[1] National Institute for Astrophysics, Astrophysical Observatory of Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy;

[2] National Research Council, Institute of Atmospheric Pollution Research, c/o University of Calabria, 87036 Rende, Italy;

关键词: sun: corona;    sun: coronal mass ejections (CMEs);    sun: oscillations;    instabilities;    plasmas;    turbulence;   

DOI  :  10.3390/atmos10080468

来源: DOAJ

【 摘 要 】

This work focuses on the interaction of a Coronal Mass Ejection (CME) with the ambient solar corona, by studying the spatial and temporal evolution of the density fluctuations observed by the SOHO/UV Coronagraph Spectrometer (UVCS) during the CME. The investigation is performed by applying a wavelet analysis to the HI Ly $\alpha$ 1216 Å line intensity fluctuations observed with UVCS during the CME occurred on 24 December 2006. Strong and coherent fluctuations, with a significant spatial periodicity of about 84 Mm $\simeq 0.12$ R ${}_{\odot }$ , are shown to develop in about an hour along the front of the CME. The results seem to indicate the Rayleigh-Taylor (RT) instability, susceptible to the deceleration of the heavier fluid of the CME front into the lighter surrounding coronal plasma, as the likely mechanism underlying the generation of the observed plasma fluctuations. This could be the first inference of the RT instability in the outer solar corona in UV, due to the transit of a CME front in the quiet coronal plasma; this interpretation is also supported by a linear magnetohydrodynamic analysis of the RT instability.

【 授权许可】

Unknown