Global Energetics of Solar Flares. VI. Refined Energetics of Coronal Mass Ejections

Abstract

In this study we refine a CME model presented in an earlier study on the global energetics of solar flares and associated CMEs, and apply it to all (860) GOES M-and X-class flare events observed during the first 7 years (2010)(2011)(2012)(2013)(2014)(2015)(2016) of the Solar Dynamics Observatory (SDO) mission, which doubles the statistics of the earlier study. The model refinements include: (1) the CME geometry in terms of a 3D sphere undergoing self-similar adiabatic expansion; (2) the inclusion of solar gravitational deceleration during the acceleration and propagation of the CME, which discriminates eruptive and confined CMEs; (4) a self-consistent relationship between the CME center-of-mass motion detected during EUV dimming and the leading-edge motion observed in white-light coronagraphs; (5) the equi-partition of the CME kinetic and thermal energy; and (6) the Rosner-Tucker-Vaiana (RTV) scaling law. The refined CME model is entirely based on EUV dimming observations (using AIA/SDO data) and complements the traditional white-light scattering model (using LASCO/SOHO data), and both models are independently capable to determine fundamental CME parameters such as the CME mass, speed, and energy. Comparing the two methods we find that: (1) LASCO is less sensitive than AIA in detecting CMEs (in 24% of the cases); (2) CME masses below m cme < ∼ 10 14 g are under-estimated by LASCO; (3) AIA and LASCO masses, speeds, and energy agree closely in the statistical mean after elimination of outliers; (4) the CMEs parameters of the speed v, emission measure-weighted flare peak temperature T e , and length scale L are consistent with the following scaling laws (derived from first principles): v ∝ T 1/2 e , v ∝ (m cme ) 1/4 , and m cme ∝ L 2 .

Forecasting Solar Energetic Particle (SEP) events with Flare X-ray peak ratios

“…Aschwanden et al (2017) have carried out a comprehensive global analysis of 399 solar flares and associated CMEs with the goal of obtaining physical scaling laws for those events. In a recent refinement of the CME model used in the earlier analysis and with an extension to 860 GOES M and X flares during 2010-2016, Aschwanden (2017) found CME speeds v and flare X-ray peak temperatures T e to be consistent with a scaling law of m~T 0:5 e . If we assume that for given flare X-ray peak fluxes, we get more SEP events because of faster CME speeds to drive the necessary shocks, then that scaling law implies that the SEP events should lie in the high, not the low, range of the peak-flux ratios of Figures 1-6.…”

Global Energetics of Solar Flares. IX. Refined Magnetic Modeling

“…One of the most important tasks in our study is the energy partition and energy closure in flares. Quantitative information on different forms of energies and their partition in flares and CMEs became more available lately (Emslie et al 2012;Mann 2016a, 2016b;Aschwanden et al 2014aAschwanden et al , 2015aAschwanden et al , 2016a2017;Aschwanden 2016aAschwanden , 2017Aschwanden and Gopalswamy 2019). Virtually no statistical study on flare energies existed 5 years ago (Aschwanden 2004(Aschwanden , 2019a.…”

Global Energetics of Solar Flares. VII. Aerodynamic Drag in Coronal Mass Ejections

“…In the study of Aschwanden (2017), energy closure is almost reached (87%±18%), where the CMEs are estimated to dissipate 7% of the available magnetic free energy. Including the energy supply by aerodynamic drag, the CME energy budget changes from 7% to 4% of the total flare energy budget, and thus it just drops slightly in the energy closure from 87% to 83%.…”

“…While the previously described results make exclusively use of LASCO/SOHO data, we compare now these measurements with other data sets based on HMI/SDO, AIA/SDO, and GOES data. In particular we focus on a subset of 576 M and X-class GOES flare events that have been observed during the first 7 years of the SDO mission (2010)(2011)(2012)(2013)(2014)(2015)(2016), for which measurements of temporal, spatial, and energetic parameters were published previously (Aschwanden 2016(Aschwanden , 2017.…”

“…Since the velocity corresponds to the product of the acceleration a and the acceleration time interval ∆t, i.e., v = a∆t, the absolute value of the unresolved acceleration a cannot be determined from LASCO observations alone, but only the product. Using EUV dimming data in addition, however, the acceleration can be resolved, as shown from AIA/SDO data (Aschwanden 2017), where a median acceleration rate of a = 0.8 km s −1 , median acceleration times of 500 s (or 7 minutes), and an acceleration height of h acc = 0.75R ⊙ have been determined ( Table 1 in Aschwanden 2017). These measurements justify the assumption that the flare-associated acceleration occurs at low coronal heights of r < ∼ 1.5R ⊙ (Gopalswamy et al 2009;Bein et al 2011), even for ground-level enhancement (GLE) events (Gopalswamy et al 2013).…”