| Presentation Title: | Observational Comparison of Coronal Magnetic Field Parameters Between Confined and Eruptive Flares in the Similar MFR Configuration |
| Author(s): | Kouhei Teraoka, Toshifumi Shimizu, Daiki Yamasaki, Yusuke Kawabata, Shinsuke Imada |
Abstract:
Solar flares are an explosive release of magnetic energy in the solar atmosphere. Magnetic flux ropes (MFRs) are a bundle of twisted magnetic field lines and are considered the energy source of flares. Some flares are associated with the eruption of MFRs and are called eruptive flares. Others fail to erupt and may be called confined flares. Eruptions are thought to be caused by magnetohydrodynamic instabilities such as the torus and kink instabilities. An experimental study by Myers et al. (2015) has shown that eruptive flares have MFRs both in torus and kink unstable states. Meanwhile, an observational study by Jing et al. (2018) has shown that eruptive flares have MFRs in the torus unstable state but are not characterized by the kink unstable state. The difference in the results may arise in that the former one compared MFRs in simple dipole configurations, whereas the latter one did in more complicated configurations. Therefore, making eruption conditions clearer by eliminating the influence of the configuration, we observationally investigated differences between the confined and eruptive flares in a similar MFR configuration. States of MFRs were identified by calculating coronal magnetic field parameters for each magnetic field line obtained by extrapolating the nonlinear force-free field from SDO/HMI data. We also focused on the magnetic field lines contributing to the energy release identified by flare ribbons in the SDO/AIA data. We examined confined and eruptive flares observed within 3 hours in AR 12673 on September 6, 2017. The results show that the magnetic field lines are more likely to be kinked unstable in the eruptive flare and less likely to be kinked unstable in the confined flare, but no difference is found in the torus instability between the flares. The presence of magnetic field lines becoming kinked unstable may make a difference in eruptivity.