From Flux Emergence to Decay – A High-resolution Study of Sunspots
Final Report Abstract
The project studied the complex interaction between solar magnetic fields and plasma flows associated with various solar features. The start of the project coincided with the onset of the COVID-19 pandemic. This required a slight modification of the original plans. Nevertheless, adequate observations were made and the necessary data from the databases were used. The main goal of this project was to construct a comprehensive picture of solar magnetic features such as pores and sunspots using multi-wavelength observations. The flow fields in the early stages of sunspot evolution were scrutinized. The combination of photospheric and chromospheric observations revealed that the onset of penumbra formation can be observed in the chromosphere long before its counterpart appears in the photosphere. Furthermore, in an active region with multiple sunspots with complete to rudimentary penumbral coverage, field-aligned flows are not a must. The light bridges have been present in both pores and sunspots. In the case of pores, the granular type light-bridge had a horizontal flow structure as expected from the numerical simulations. However, in the case of sunspots, it was difficult to deduce the horizontal flow structure in the thin light bridges. The third and final part of the thesis deals with a light bridge in a mature sunspot with complete penumbral coverage observed in both photospheric and chromospheric spectral data with long coverage. This will enable us to investigate the role of light bridges in the final stages of sunspot evolution. The two studies related to the application of t-SNE to solar spectra and spectropolarimetric data presented new ways to classify and identify new patterns in the data. The onion-peel magnetic structure of small pores and the intricate structure of the surge were seen through the t-SNE classification.
Publications
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Classification of High-resolution Solar Hα Spectra Using t-distributed Stochastic Neighbor Embedding. The Astrophysical Journal, 907(1), 54.
Verma, Meetu; Matijevič, Gal; Denker, Carsten; Diercke, Andrea; Dineva, Ekaterina; Balthasar, Horst; Kamlah, Robert; Kontogiannis, Ioannis; Kuckein, Christoph & Pal, Partha S.
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Filigree in the Surroundings of Polar Crown and High-Latitude Filaments. Solar Physics, 296(2).
Diercke, Andrea; Kuckein, Christoph; Verma, Meetu & Denker, Carsten
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Multiple Stokes I inversions for inferring magnetic fields in the spectral range around Cr I 5782 Å. Astronomy & Astrophysics, 653, A165.
Kuckein, C., Balthasar, H., Quintero Noda, C., Diercke, A., Trelles Arjona, J. C., Ruiz Cobo, B., Felipe, T., Denker, C., Verma, M., Kontogiannis, I. & Sobotka, M.
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Wavelength Dependence of Image Quality Metrics and Seeing Parameters and Their Relation to Adaptive Optics Performance. Solar Physics, 296(2).
Kamlah, R.; Verma, M.; Diercke, A. & Denker, C.
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Characterization of chromospheric activity based on Sun‐as‐a‐star spectral and disk‐resolved activity indices. Astronomische Nachrichten, 343(5).
Dineva, Ekaterina; Pearson, Jeniveve; Ilyin, Ilya; Verma, Meetu; Diercke, Andrea; Strassmeier, Klaus G. & Denker, Carsten
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High-resolution imaging of solar pores. Astronomy & Astrophysics, 675, A182.
Kamlah, R.; Verma, M.; Denker, C. & Wang, H.
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Study of Global Photospheric and Chromospheric Flows Using Local Correlation Tracking and Machine Learning Methods I: Methodology and Uncertainty Estimates. Solar Physics, 298(5).
Li, Qin; Xu, Yan; Verma, Meetu; Denker, Carsten; Zhao, Junwei & Wang, Haimin
