Austrian Early Career Conference 2024

Contribution:
Talk

Authors:
Isabella Kraus; Philippe-A. Bourdin

Affiliations:
Institute of Physics, University of Graz

Title:
Statistics of Coronal Bright Points and Preparation of a CBP Simulation with Hinode and SDO data

Abstract:
The exact coronal heating mechanism remains a riddle, but magnetically active regions are known to trigger extreme-UV emission along coronal loops. Also at much smaller scales, there are small bipolar regions that can be associated with evenly sized coronal bright points (CBPs). We study the statistical properties of CBPs with continuous data from the SDO spacecraft to track the lifetime of CBPs. We aim to verify if the lower corona co-rotates with the photosphere. From 346 CBPs we extract information on their lifetime, size, shape, polarity, etc. We then compare the CBP lifetime with its shape and EUV visibility. From the CBP tracking algorithm we confirm a strict co-rotation of the CBPs with the photospheric differential rotation. Furthermore, we like to reproduce one CBP in a 3D magneto-hydrodynamic simulation. A vertical Poynting flux is created from horizontal advection motions in the photosphere that perturb the magnetic field. We verify if the coronal heating is from Ohmic dissipation of direct currents. The observational data for the CBP simulation is obtained from the Hinode/SOT instrument and is complemented with SDO/HMI data. This allows us to enlarge the field-of-view, so that the simulation is driven fully by observed photospheric magnetic fields. The bottom and top model boundaries are fully closed for mass and heat flows. The hottest and brightest CBPs seem to exist for significantly longer time, up to 24 hours, than compared to fainter CBPs. The merging of two CBPs has no influence on the overall size of the persisting CBP. We also find that the merging of two CBPs is a relatively rare phenomenon. Loop-like CBPs are usually bipolar and their merging probability is low. Weaker magnetic polarities produce fainter and cooler CBPs. This supports that the CBP heating is mainly based on magnetic energy dissipation.