Fine structure of sunspot umbrae

• Applicant: Professor Dr. Wolfgang Schmidt, since 3/2016
• Subject Area: Astrophysics and Astronomy
• Term: from 2012 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 211197835

Sunspots are the principal tracers of the solar magnetic activity. Observations of sunspots at high spatial resolution reveal that there exists a fine structure inside the umbra, the central dark core of sunspots. The goal of this project is to understand the mechanisms that on the one side provide a week-long stability of sunspots, but eventually lead to their disappearance. The energy transport in the umbra of sunspots on small spatial scales plays a vital role in this context. To this end we will investigate the energy transport at small spatial scales in the photosphere and chromosphere by means of convection and waves. Besides the investigation of the short-term dynamic evolution, we will also study the long-term evolution of sunspots in relation to the large-scale magnetic field topology (current sheets, twist). The atmospheric parameters will be derived by an inversion of observed spectra. The magnetic field plays an important role in the sunspot atmosphere both in the photosphere and chromosphere by magnetic reconnection, current dissipation, wave channeling, and mode conversion of waves. Thus, we measure the magnetic field vector, temperature and mass flows. To investigate the short and long-term variation of the umbra, we will use rapid small-scale time-series and repeated large-area scans, respectively. We will compare our results with recent 3D simulations of sunspots using synthesized spectra from simulation snapshots.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Reza Rezaei, until 2/2016