Small-scale magnetic fields in the solar atmosphere

点击翻译按钮获取中文摘要

Small-scale magnetic structures in the photosphere of the sun play a key role for the solar irradiance variability as well as for the energy transport to the corona. Most magnetic flux concentrations are visible as bright round or elongated objects with a magnetic field strength of about 0.1 T. In this project we intend to observe the magnetic field, the plasma motion and the intensity as a function of time of various kinds of small magnetic elements. The study of their formation, evolution and disappearance will provide insight in basic magneto-convective processes that take place on the sun. With imultaneous measurements of magnetic and flow field we aim to answer how the magnetic flux is concentrated to its observed value and how it decays again. At the same time, we seek to understand how the magnetic flux is brought to the solar surface and how it disappears again. We use high-precision spectro-polarimetry to measure the magnetic field at a spatial resolution down to 0.25 arcs (160 km on the sun) by using spectro-polarimeters at the German Vacuum Tower Telescope. These instruments permit simultaneous observation in several spectral bands in the visible and the near UV. In order to derive the magnetic field and other physical quantities from the data, we will employ pectral line inversion techniques. Our results will be compared to predictions from numerical simulations and will provide important boundary conditions for theoretical and numerical models.