Abstract Details

Name: Surajit Mondal
Affiliation: National Centre for Radio Astrophysics
Conference ID: ASI2021_245
Title : Detection of sausage MHD modes using radio observations of solar noise storms
Authors and Co-Authors : Surajit Mondal (NCRA-TIFR) and Divya Oberoi (NCRA-TIFR)
Abstract Type :
Abstract Category : Sun and the Solar System
Abstract : Type I solar noise storms are among the most common active radio emissions, especially in the metric wavelengths. The presence of magnetohydrodynamic (MHD) waves in type I noise storms is now well accepted and are usually inferred from observations of quasi-periodic pulsations (QPPs) at time scales timescales ranging from a few seconds to several minutes (e.g. Nakariakov et al. 2009 and, Carley et al. 2019). Mohan et al. (2019) recently reported simultaneous observation of QPPs in a type III radio burst along with a strong anti-correlation between the observed source size and the integrated flux density of the burst source. They argued both of these observations can be simultaneously explained by modulation of the nonthermal electron electron beams at the reconnection site. We note that detection of QPPs in a time series necessarily requires the sustained presence of pulsations at a dominant time scale. However, the anti-correlation between the morphological parameters of burst source is expected to remain observable even when either no dominant QPP is present or multiple periodicities are simultaneously present. Using high fidelity solar radio images from the Murchison Widefield Array, we investigate this possibility. We find robust evidence for the existence of such anti-correlations for a weak type I noise storm even during its quiescent phase, implying the presence of sausage oscillation modes. Here we will present the results from this study and showcase this as a novel approach, made possible by modern instruments, to uncover previously unappreciated aspects of dynamics of well observed emissions like type I noise storms.