Abstract Details


Name: Bablu Mandal
Affiliation: ARIES
Conference ID: TVS202510137
Title: A Spatio-Temporal Study of a Quasi-Steady Supersonic Downflow in AR 12135 using IRIS data
Authors and Co-Authors: S. Krishna Prasad
Abstract Type: Contributory Presentation
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 (SSDs), a very unique phenomenon, are usually observed above sunspots as redshifted components in the transition region spectral lines. These localised transient events occur in more than 80 per cent of sunspots, often recur at the same location within a timescale of a few minutes to hours and their speed ranges between 50 to 200 km/s. Short-lived and Rapid SSDs are previously linked to Coronal Rain, while the exact origin of Quasi-Steady SSDs remains debatable. In this work, we investigate the short-term dynamics of a quasi-steady SSD in AR 12135 by utilising a nearly 3-hour Interface Region Imaging Spectrograph (IRIS) dataset. After carefully checking the spectra, we performed triple Gaussian fitting with specific constraints to transition region spectral lines on each pixel to study the spatial morphology as well as the temporal variation of this event. Our analysis revealed that the downflow is initially seen 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 found that on certain occasions, the downflow seems to originate from the region between the hotter plasma loops. We also derived average properties like downflow speed, electron density, and mass flux of this event over the umbral region.