Name: Dr Rakesh Mazumder
Affiliation: Aryabhatta Research Institute of Observational Sciences (ARIES)
Conference ID : ASI2022_417
Title : Solar Filaments: A Study of Their Long Term Variability and Seismology
Authors : Dr Rakesh Mazumder
Abstract Type: Oral
Abstract Category : Thesis
Abstract : The thesis is focused on the study of solar filament oscillation and long-term variation of filament properties. First part of the thesis is on filament oscillation using data from NSO/GONG and AIA and HMI onboard SDO. Rest of the thesis contains the study of long term evolution of properties of filament from archival databases. We detect oscillation of filament by placing artificial slits on filament images. We use the simple pendulum model to estimate the magnetic field in filament. We estimate the radius of curvature of the filament using the same model. These studies are important for constraining filament dynamics. In the second part of the thesis, we study long term variability of filament properties from McIntosh database and Meudon database. The total length of the filament is found to vary periodically with a high correlation with sunspot area variation. The distribution of filament in longitude is found to be uniform. However, their distribution in latitude is observed to be bimodal. The temporal variation of latitude distribution of filament shows a butterfly pattern. We observe the poleward migration of filaments in the temporal variation of latitude distribution of filament and it is found to be cotemporal with polar magnetic field reversal. We analyze the tilt angle of filaments in detail to find the origin of the filaments. We conclude that most filaments are formed from large scale structures which can explain our observed unexpected filament tilt distribution. So our study establishes that seismology is a great tool to obtain plasma-parameters of the filaments, which is difficult to measure directly. The study of long term variation of parameters of the filaments and especially the tilt angles reveals that large scale structures are the main origin of the filaments.