Numerical simulations of sunspot decay: On the role of a penumbra and subsurface field structure
Abstract
We present high-resolution simulations of decaying sunspots that cover a time span of up to 100 hours. The simulations reach 18Mm deep into the convection zone and use open boundaries that do not maintain the initial field structure against decay driven by convective motions. We discuss three experiments: A sunspot simulation with penumbra, a "naked-spot" simulation in which we removed the penumbra after 20 hours, and a sunspot simulation with penumbra, but a less coherent subsurface field structure. In all three simulations we study the decay process and large-scale flows in proximity of the spots. Over the time span covered by the simulation the spot with penumbra is almost stationary with regard to the total flux content, but shows a steady decay of the flux present in the umbra area at a rate comparable to the "naked-spot" experiment. A less coherent sub-surface magnetic field structure leads within 12-24 hours to a less coherent surface appearance, i.e. details of the subsurface structure do not remain hidden from the photosphere. In all three experiments the dominant subsurface flow patterns are outflows.
- Publication:
-
American Astronomical Society Meeting Abstracts #224
- Pub Date:
- June 2014
- Bibcode:
- 2014AAS...22420204R