NASA's Interface Region Imaging Spectograph confirms simulation of origin of dynamic jets on the Sun

The surface of the sun is populated with short lived jets of solar material known as spicules. At any given point of time, there are ten million of these on the sun. Each spicule can be up to 9,600 kilometers long and reach speeds of up to 96 kilometers per second. As they are very short lived, less than five to ten minutes, the exact process by which spicules form have so far been unknown. NASA used a simulation that took a year to complete, based on a numerical model prepared over the course of ten years, to figure out the origin of the spicules. The computer models showed that the interaction between charged and neutral particles with the magnetic field of the Sun was an important part of the process of spicule formation. The interaction straightens tangled magnetic field lines, which drive the jets of material away from the surface of the sun at high speeds. The models were confirmed with direct observations from NASA’s Interface Region Imaging Spectograph (IRIS) and the Swedish 1-meter Solar Telescope.

Juan Martínez-Sykora, lead author of the study said “Usually magnetic fields are tightly coupled to charged particles. With only charged particles in the model, the magnetic fields were stuck, and couldn’t rise beyond the sun’s surface. When we added neutrals, the magnetic fields could move more freely.” The neutral particles provide the buoyancy to tangled knots of magnetic energy to rise to the surface of the sun, where they get unraveled into spicules, releasing plasma and energy. Friction between ions and neutral particles further heat up the plasma in and around spicules. The finding advances the scientific understanding of the surface of the Sun, and lays the groundwork for further investigations into the role that spicules play in the atmosphere of the Sun.