Magnetic bright points on the solar photosphere, visible in both continuum and G-band images, indicate footpoints of kilogauss magnetic flux tubes extending to the corona. The horizontal motions of these footpoints are believed to excite MHD waves which propagate to the corona, where they deposit heat through turbulent dissipation. Analyzing this motion can thus provide a power spectrum of MHD wave energy transport, which is a key lower boundary condition in coronal and heliospheric models. At 100 km across, most bright points are seen as unresolved blobs. Tracking their centroids allows the excitation of kink-mode waves to be modeled. However, centroid tracking struggles with the merging or splitting of bright points and with extremely long bright points. And while DKIST promises to resolve the sizes and shapes of bright points (with changes in these properties expected to excite sausage-mode and higher-order waves), centroid tracking ignores this additional information. Additionally, Agrawal et al. (2018) showed that centroid tracking is likely to experience a spurious ""jitter"" signal which may dwarf true centroid motion at DKIST's resolution and cadence. We present progress developing an algorithm that is resilient to centroid jitter and can treat merging, splitting, and shape changes properly. It will infer the horizontal plasma flow inside bright points in a way appropriate for the limited resolution of bright-point observations, and we will use these inferred flows to model the waves (kink-mode, sausage-mode, and other modes) generated in the overlying flux tubes. We are developing and testing this procedure now with simulated images from high-resolution MURaM simulations in order to be prepared to analyze DKIST images upon availability. This work will estimate the significance of the contribution to the coronal heating budget of these more complex waves and provide a more complete lower boundary condition for coronal and heliospheric models.
Solar Heliospheric and INterplanetary Environment (SHINE 2019)
- Pub Date:
- May 2019