PLASMA HEATING DURING A CORONAL MASS EJECTION OBSERVED BY THESOLAR AND HELIOSPHERIC OBSERVATORY

Abstract

We perform a time-dependent ionization analysis to constrain plasma heating requirements during a fast partial halo coronal mass ejection (CME) observed on 2000 June 28 by the Ultraviolet Coronagraph Spectrometer (UVCS) aboard the Solar and Heliospheric Observatory (SOHO). We use two methods to derive densities from the UVCS measurements, including a density sensitive O v line ratio at 1213.85 and 1218.35 Å, and radiative pumping of the O vi λλ1032, 1038 doublet by chromospheric emission lines. The most strongly constrained feature shows cumulative plasma heating comparable to or greater than the kinetic energy, while features observed earlier during the event show plasma heating of order or less than the kinetic energy. SOHO Michelson Doppler Imager observations are used to estimate the active region magnetic energy. We consider candidate plasma heating mechanisms and provide constraints when possible. Because this CME was associated with a relatively weak flare, the contribution from flare energy (e.g., through thermal conduction or energetic particles) is probably small; however, the flare may have been partially behind the limb. Wave heating by photospheric motions requires heating rates to be significantly larger than those previously inferred for coronal holes, but the eruption itself could drive waves that heat the plasma. Heating by small-scale reconnection in the flux rope or by the CME current sheet is not significantly constrained. UVCS line widths suggest that turbulence must be replenished continually and dissipated on timescales shorter than the propagation time in order to be an intermediate step in CME heating.

Recurrent CME-like Eruptions in Emerging Flux Regions. I. On the Mechanism of Eruptions

“…In our case, the flux tube axis emerges only up to 2-3 pressure scale heights above the photosphere (z=0), and the erupting FRs are all formed due to the reconnection of J-loops. Murphy et al (2011) discussed possible heating mechanisms for the dynamic heating of CMEs, one of which is heating from the CME flare current sheet. Taking into account the results of previous studies (e.g., Lin et al 2004), they reported that the reconnection of hot upward jets from the flare current sheet could reach the cool central region of the erupting FR and heat it.…”

Mass-loss Rates from Coronal Mass Ejections: A Predictive Theoretical Model for Solar-type Stars

“…The kinetic energy flux is not always the largest term in the energy budget of individual "parcels" of solar wind (Le Chat et al 2012) or CME (Murphy et al 2011) plasma, but it serves well to quantify the overall amount of material ejected in this form. The assumption of time-steady outflow is highlighted in the last expression in Equation (3), which presumes mass conservation,Ṁ = 4πρur 2 ,…”

Plasma Heating Inside Interplanetary Coronal Mass Ejections by Alfvénic Fluctuations Dissipation

“…However, the mechanism that dissipates magnetic energy into thermal energy is still an open question. In the literature, several candidate mechanisms were proposed to heat the CME plasma, which are listed as follows: (1) outflows from the CME current sheets (Bemporad et al 2007); (2) kink instability (e.g., Rust & LaBonte 2005); (3) small-scale magnetic reconnection (Furth et al 1963); (4) damping of MHD waves; (5) thermal conduction along the magnetic field (Landi et al 2010); (6) energetic particles; (7) counteracting flows (Filippov & Koutchmy 2002); and (8) ohmic heating from net current in the flux rope (Murphy et al 2011).…”