HAO Colloquium - Maurice Wilson, Harvard CfA

Constraining the CME Core's Heating and Energy Budget with SOHO/UVCS

We describe the energy budget of a coronal mass ejection (CME) observed on 1999 May 17 with the SOHO/UVCS instrument.  We constrain the physical properties of the CME's core material as a function of height along the corona by using the spectra and photometry taken by the same single-slit coronagraph spectrometer at heliocentric distances of 2.6 and 3.1 solar radii.  We use plasma diagnostics from intensity ratios, such as the O VI doublet, to determine the velocity, density, and temperature of the core material.  We perform time-dependent, non-equilibrium ionization calculations to determine the ionization states and focus primarily on four ions: H I, O V, O VI, and C III.  Using these observationally constrained physical properties, we deduce the initial conditions of the CME with respect to the various plasma heating parameterizations we investigated.  Amongst the four ions we accounted for, we find that the CME core's velocity is 250 km/s, and its cumulative heating energy is comparable to its kinetic energy.  Therefore, a continuous source of heating energy should be included as a significant portion of the total energy within physical CME models.

Date and time: 
Wednesday, September 1, 2021 - 2:00pm to 3:00pm