The Principal Investigator (PI) and his research team will investigate the transport of helicity from the solar interior through the photosphere and into the corona, in order to better understand the role of helicity in triggering solar flares and coronal mass ejections (CMEs). The PI will undertake a statistical study of almost 1,000 solar active regions observed by ground-based and space-based instruments. Using techniques he and his team have previously developed, the PI will calculate the kinetic helicity of subphotospheric flows associated with these regions and investigate the evolution of that helicity erupting through the solar surface. This idea of treating the solar interior and corona as a single coupled system is innovative and potentially transformative.
This interdisciplinary investigation will have direct benefits to space weather forecasting. The PI and his team will compare changes in the pattern and amplitude of kinetic helicity below the photosphere, and the magnetic helicity of photospheric and coronal fields with flare and CME activity of active regions, with the goal of achieving better predictions of solar flares and CME eruptions. The PI will present the results of this research at annual scientific meetings and workshops.
SHINE research focuses in particular upon the connection between events and phenomena on the Sun and their relation to solar wind structures in the inner heliosphere. The goal of SHINE activities is to enrich and strengthen both physical understanding and predictive capabilities for these phenomena. This is important since modern society is highly dependent on technology, including navigation and communication, which can be disrupted by eruptive events originating on the Sun. Solar magnetic fields are noticeable on the solar surface as sunspots and active regions and come in many sizes and shapes. They extend from below the solar surface through the solar atmosphere into the interplanetary medium. They are also the locations of eruptive phenomena, such as flares, that release a tremendous amount of energy and can disrupt technology on Earth. The resulting space weather creates not only the beautiful polar lights but also affects the accuracy of navigation systems (GPS) and threatens the safety of astronauts. The twisted magnetic fields are very probably responsible for the most geo-effective solar phenomena such as coronal mass ejections (CMEs) and flares. Excess of twist in magnetic structures in the corona, the outer part of the solar atmosphere, leads to their instability and eruption. It is thus of interest to understand the origin of this twist to improve space weather forecasting. These magnetic fields originate in the solar interior, where they cannot be directly measured. Currently, the only way to measure anything below the solar surface is with helioseismology, which studies changes in sound waves as they travel through the solar interior just as seismology is used in geophysics to study the Earth’s interior. With helioseismic techniques it is possible to measure flows in the solar interior. The question is whether these flows can be used as a proxy for magnetic activity. For example, active regions associated with strongly twisted subsurface flows are very flare productive. The so-called helicity is a measure of the twist and can be determined for magnetic fields as well as for flows. The goal of this project was to directly relate the twist of subsurface motions to the twist of magnetic structures in the solar atmosphere and to determine the transport of helicity from the interior to the solar atmosphere. The key result is that the twist of subsurface flows can indeed be used as a proxy of the twist of magnetic fields. A statistical comparison between atmospheric twist parameter of active regions and interior kinetic helicity shows that they have the same sign on average. Flows in the solar interior that are twisted in one direction cause the magnetic field in the solar atmosphere to be twisted in the same direction.
