Abstract Details

Name: Devojyoti Kansabanik
Affiliation: National Center for Radio Astrophysics - Tata Institute of Fundamental Research
Conference ID: ASI2021_58
Title : Estimating plasma parameters of coronal mass ejections at higher coronal heights using high fidelity low-frequency radio images
Authors and Co-Authors : Devojyoti Kansabanik (National Centre for Radio Astrophysics - Tata Institute of Fundamental Research), Surajit Mondal (National Centre for Radio Astrophysics - Tata Institute of Fundamental Research), Divya Oberoi (National Centre for Radio Astrophysics - Tata Institute of Fundamental Research), Angelos Vourlidas (Applied Physics Laboratory, Laurel, United States)
Abstract Type : Oral
Abstract Category : Sun and the Solar System
Abstract : Coronal Mass Ejections (CMEs) are large scale explosive eruptions of magnetised plasma from the Sun into the Heliosphere. Measuring the physical parameters of CMEs is crucial for understanding their physics and for assessing their geo-effectiveness. Radio observations offer the most direct means for estimating these plasma parameters when gyrosynchrotron (GS) emis- sion is detected from the CME plasma. However, since the first detection by Bastian et al. (2001), only a handful of studies have successfully detected GS emission from CME plasma. This is usu- ally attributed to the challenges involved in obtaining the high dynamic range imaging required for observing this faint gyrosynchrotron emission in the vicinity of active solar emissions. The newly developed imaging pipeline (Mondal et al., 2019) designed for the data from Murchison Widefield Array (MWA) marks a significant improvement in metrewave solar radio imaging. We now expect to routinely detect GS emission from CME plasma. We present an example where we have successfully detected radio emission from CME plasma, modelled it as GS emission, leading to reliable estimates of CME magnetic field and the distribution of energetic electrons. In a different example, we find that the observed spectra are not always consistent with simple GS models. For this CME we detect the CME radio emission out to as far as 8.3 solar radii. This highlights that more complicated physics might be at play and points to the need for building more detailed models for interpreting these emissions. These are the weakest detections of GS emissions from CME plasma reported yet. Polarimetric imaging is expected to further improve this approach to estimating CME magnetic fields and other physical parameters. Here we also present our first attempts at polarimetric imaging and modeling of CME gyrosynchroton emission.