SPRG Seminars
January 28, 2014:
"The generation mechanism of MHD waves in flux tubes"
Yoshiaki Kato, Hinode Science Center, National Astronomical Observatory of Japan (NAOJ)
In this talk, I would like to introduce a new theoretical insight regarding the yet unknown process, which causes the chromospheric emission in the network and plage regions of the solar atmospheres. It is probably also relevant for the excitation of dynamic fibrils and spicules. In the past, models and simulations of this process have always relied on a prescribed driving mechanism. In the paper (Kato, Steiner, Steffen, and Suematsu 2011), for the first time, we describe a self-consistent mechanism of wave generation ---the turbulent pumping. Convective downdrafts in the close surroundings of the flux tube "pump" the flux tube atmosphere in the downward direction. This action produces a downflow in the flux tube and excites the slow mode by the adiabatic compression of the donwflow near the optical surface. The slow mode travels upward and develops into a shock at the chromospheric height. I will discuss more theoretical/observational insights on the chromospheric/coronal oscillations based on the recent numerical experiments.