| Name: Bablu Mandal |
| Affiliation: ARIES Nainital |
| Conference ID: ASI2026_707 |
| Title: Exploring Spatio-Temporal Evolution of a Long-lived Supersonic Downflow in AR 12135 |
| Abstract Type: Poster |
| Abstract Category: Sun, Solar System, Exoplanets, and Astrobiology |
| Author(s) and Co-Author(s) with Affiliation: Bablu Mandal(Aryabhatta Research Institute of Observational Sciences, Nainital-263002, Uttarakhand, India), S. Krishna Prasad(Aryabhatta Research Institute of Observational Sciences, Nainital-263002, Uttarakhand, India), Avijeet Prasad(Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315, Oslo, Norway) |
| Abstract: Flows in active regions have been a long-standing region of interest owing to their connection with the mass and energy transfer in the upper Solar atmosphere. Super-sonic Downflows are usually observed above sunspots as red-shifted components in the Transition Region (TR) spectral lines. These localised events occur in more than 80 per cent of sunspots, often recur at the same location with a timescale of a few minutes to hours. In this work, we investigate the short-term dynamics of a long-lived SSD in AR 12135 by utilising almost 3h long Interface Region Imaging Spectrograph (IRIS) observations. Instead of traditional double Gaussian fitting, triple Gaussian fitting with specific constraints is performed on each pixel of the TR spectral lines (Si IV 1394 & 1402, O IV 1399 & 1401) to study this event. Our analysis reveals that downflow is initially observed in both the umbral and penumbral regions. Over time, the penumbral downflow fades, while the umbral downflow strengthens and appears as a single structure that eventually splits into two spatial segments. By combining IRIS Spectroscopic observations with imaging data from the Atmospheric Imaging Assembly (AIA), we find that changes in the downflow’s morphology are linked to alternations in the coronal loops’ structure. Non-Force Free Field extrapolation indicates that a fan-spine magnetic topology is present near the sunspot. As observed from AIA images, magnetic reconnection near this site is the most probable reason for this splitting. Before the spitting event, we also observed a rare anomalous motion of the loop’s footpoint above the sunspot’s atmosphere in both IRIS as well as AIA channels. Derived average properties such as downflow speed, electron density, and mass flux of this event over the umbral region are consistent with existing studies.
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