Abstract Details


Name: Souvik Bose
Affiliation: Lockheed Martin Solar & Astrophysics Lab/SETI institute
Conference ID: TVS202510264
Title: Heating of Solar Coronal Loops by Magnetic Flux Convergence: Insights from Observations and a 3D MHD Simulation
Authors and Co-Authors: Sanjiv Tiwari, Juan Martínez-Sykora, Navdeep Panesar
Abstract Type: Invited by SOC
Abstract: Solar coronal loops are bright, closed magnetic structures anchored in the photosphere and extending into the upper atmosphere. In emerging flux regions, loop formation and initial heating occur as strong magnetic flux tubes, carrying hot plasma, puncture the photosphere, allowing plasma to flow along the field lines. Over time, the loop footpoints separate. In this study, we focus on the heating of quiet region (QR) coronal loops after their footpoints have already separated. Our observations reveal that flux convergence—where smaller unipolar photospheric magnetic flux patches merge into a stronger flux patch—often correlates with loop heating, while flux divergence correlates with loop cooling. This behavior is similar to recent findings in solar coronal plumes. To investigate and quantify the magnetic basis of this heating, we analyze 10 QR coronal loops throughout their lifetimes using SDO/AIA 171 Å and 94 Å images, along with SDO/HMI magnetograms. The luminosity time series shows a strong correlation with magnetic flux at least at one footpoint, particularly when the line-of-sight magnetic field strength (B$_{los}$) exceeds a threshold of $\approx$200–600 G. Additionally, Bifrost MHD simulations of a network region exhibit similar behavior: magnetic flux convergence and divergence—often more dominant at one loop footpoint—directly correlate with loop formation (increased emissivity) and disappearance (diminished emissivity). The simulation further shows an increase in Poynting flux, reconnection rate, and Joule heating, associated with the flux convergence at one of the footpoints. We hypothesize that an increased number density of nanoflares during flux convergence is a possible explanation for heating these loops.