In this study, we investigate the energy partition of four confined circular-ribbon flares (CRFs) that occurred close to solar disk center. The flares are observed simultaneously by the Solar Dynamics Observatory (SDO), the Geostationary Operational Environmental Satellites (GOES), and the Ramaty Hight Energy Solar Spectroscopic Imager (RHESSI). We calculate different energy components, including the radiative outputs in the ranges 1 - 8 Å, 1 - 70 Å, and 70 - 370 Å, total radiative loss, peak thermal energy derived from GOES and RHESSI, nonthermal energy in flare-accelerated electrons, and magnetic free energy before the flares. It is found that the values of energy components increase systematically with the flare class, indicating that more energy is involved in larger flares. The magnetic free energies (Em a g) are larger than the nonthermal energies (En t h) and radiative outputs, which is consistent with the magnetic nature of flares. The ratio E/nt hEm a g of the four flares, being 0.70 - 0.76, is considerably higher than that of eruptive flares. Hence, this ratio may serve as an important factor for discriminating confined from eruptive flares. The nonthermal energies are sufficient to provide the heating requirements including the peak thermal energy and radiative loss. Our findings impose constraints on theoretical models of confined CRFs and have potential implications on space weather forecast.
- Pub Date:
- April 2021
- energetic particles;
- in flares;
- Magnetic fields;
- Astrophysics - Solar and Stellar Astrophysics
- 20 pages, 14 figures, accepted for publication in Solar Physics, comments are welcome