Collisional Shearing: A Possible Mechanism Producing Recurrent Explosive (Flare and CME) Activity in Solar Active Regions
Speaker: Georgios Chintzoglou, LMSAL
Solar Active Regions (ARs) are produced by the emergence of strong magnetic fields generated in the solar interior. ARs can be further classified into (a) simple and (b) complex. Simple ARs appear on the Sun as one magnetic bipole (i.e., composed of one positive and one negative magnetic polarity/sunspots) and they do not produce significant activity. Complex ARs are composed of multiple polarities and can be the source of intense explosive activity on the Sun, producing solar flares and CMEs.
In this work, we focus on such complex and developing ARs composed of multiple magnetic bipoles that emerge in close proximity to each other. Due to the compact clustering of the different emerging bipoles within such complex multipolar ARs, collision and shearing between opposite non-conjugated polarities produce “collisional polarity inversion lines” (cPILs) and drive rapid cancellation of magnetic fields at the surface of the Sun. The strength and the duration of the collision, shearing, and cancellation are defined by the natural separation of the conjugated polarities during the emergence phase of each bipole in the host AR. This mechanism is called “Collisional Shearing”. Chintzoglou et al (2019) demonstrated that collisional shearing occurred in two well-observed emerging and evolving flare- and CME-productive ARs (NOAA AR11158 and AR12017) by measuring significant amounts of magnetic flux canceling at the cPIL. Our proposed mechanism supports the recurrent formation and energization of magnetic flux ropes (i.e., twisted magnetic field structures) before their eruption as CMEs.
We discuss the relevance of our results in explaining the cause of recurrent explosive activity on the Sun.
Georgios Chintzoglou joined Lockheed Martin Advanced Technology Center (LMATC) in July 2021 as Senior Research Scientist. He comes from UCAR, where he was a Project Scientist I working directly with the AIA and IRIS science teams. From 2016-2019, he was a postdoc at UCAR via the Visiting Scientist Program. His Ph.D. (2016) in Physics and M.S. (2013) in Engineering Physics are from George Mason University, and he received his B.Sc. (2009) in Physics from the University of Ioannina in Greece, of which he is a native.
Dr. Chintzoglou’s primary research areas are in the physics of Solar Magnetism, Solar Active Region evolution and associated activity, and CME initiation theory as well as interpretation of observations.
Having a strong interest in instrumentation, Dr. Chintzoglou is an instrument scientist working on the calibration of the IRIS mission. He is also actively involved in the design and development of the slit-jaw imager instrument of the upcoming Extreme Ultraviolet Solar Telescope (EUVST; a joint NASA/JAXA mission) and also in the design, testing and development of the Multi-slit Solar Explorer (MUSE), a newly selected NASA MIDEX mission.