An Estimate of the Magnetic Field Strength Associated With a Solar Coronal Mass Ejection From Low Frequency Radio Observations

Abstract

We report ground based, low frequency heliograph (80 MHz), spectral MHz) and polarimeter (80 and 40 MHz) observations of drifting, non-thermal radio continuum associated with the 'halo' coronal mass ejection (CME) that occurred in the solar atmosphere on 2013 March 15. The magnetic field strengths (B) near the radio source were estimated to be B ≈ 2.2 ± 0.4 G at 80 MHz and B ≈ 1.4±0.2 G at 40 MHz. The corresponding radial distances (r) are r ≈ 1.9 R ⊙ (80 MHz) and r ≈ 2.2 R ⊙ (40 MHz). Subject headings: Sun -activity: Sun -flares: Sun -corona: Sun -radio radiation: Sun: coronal mass ejections (CMEs): Sun -magnetic topologythe referee for his/her comments that helped to bring out the results more clearly. The SOHO data are produced by a consortium of the Naval Research Laboratory (USA),

Variation in Coronal Activity from Solar Cycle 24 Minimum to Maximum Using Three-Dimensional Reconstructions of the Coronal Electron Density from STEREO/COR1

“…This suggests that our SSPA 3D coronal density models reconstructed for 100 CRs (with a cadence of about two weeks) may be used for the interpretation of radio bursts (such as type II and moving type IV produced by CMEs) as observed from the Earth direction (e.g. Cho et al, 2007;Ramesh et al, 2013;Shen et al, 2013;Sasikumar Raja et al, 2014;Hariharan et al, 2016;Lee et al, 2016), in particular, when LASCO/C2 pB data are not available. We estimate the total mass (or electron content) contained in the coronal region observed with COR1 and its evolution with solar cycle.…”

New Results on the Direct Observations of Thermal Radio Emission from a Solar Coronal Mass Ejection

“…Note that for nonthermal gyrosynchrotron emission from a CME, the T b values predicted by the model are higher than the aforementioned observed T b values by about a factor of four, even for the lowest values assumed for the different parameters in the model. Low‐frequency observations reported earlier also indicate that the observed T b of gyro‐synchrotron emission from a CME is ∼10 7 −10 8 K (Dulk, 1985; Gary et al., 1985; Gopalswamy & Kundu, 1987, 1990; Sasikumar Raja et al., 2014; Wagner et al., 1981).…”

“…The radio emission associated with and/or from the CMEs can be divided into two classes, thermal and nonthermal (e.g., Vourlidas, 2004). In the nonthermal case, type IV radio bursts due to gyrosynchrotron and/or plasma emission from the electrons in the CME (Bain et al., 2014; Bastian et al., 2001; Carley et al., 2017; Gary et al., 1985; Gopalswamy & Kundu, 1987, 1989, 1990; Hariharan, Ramesh, Kathiravan, & Wang, 2016; Maia et al., 2007; Mondal et al., 2020; Morosan et al., 2019; Ramesh et al., 2013; Sasikumar Raja et al., 2014; Stewart et al., 1974; Tun & Vourlidas, 2013; Vasanth et al., 2019; Wagner et al., 1981), type II radio bursts due to plasma emission from the electrons accelerated by MHD shocks driven by the CME (Aurass, 1997; Chrysaphi et al., 2018; Gopalswamy, 2006; Kumari et al., 2017, 2017b, 2019; Maguire et al., 2020; Mann et al., 1995; Ebenezer et al., 2001b; Ramesh et al, 2010b, 2012a; Stewart et al., 1974), and type I noise storm continuum due to plasma emission from changes in the coronal magnetic field during a CME (Kathiravan et al., 2007; Kerdraon et al., 1983; Ramesh & Sundaram, 2000a) have been widely reported. Compared to this, there are only a few reports of direct detection of CMEs at radio frequencies via thermal bremsstrahlung emission (Gopalswamy & Kundu, 1992, 1993; Kathiravan et al., 2002; Kathiravan & Ramesh, 2004, 2005; Ramesh, 2005a; Ramesh et al., 2003; Sheridan et al., 1978).…”

Radio Observations of Coronal Mass Ejections: Space Weather Aspects

“…The SpWx relevance of "radio" CMEs and mIVs lies in their emission mechanism. If it is synchrotron, as commonly assumed in the analyses (e.g., Tun and Vourlidas, 2013;Sasikumar Raja et al, 2014;Carley et al, 2017;Mondal et al, 2019), then their detection provides a means to estimate the (total) magnetic field entrained in the CME, while the CME is still in the low corona. Such information could help improve prediction schemes of the geoeffectiveness of the transient when augmented, say, with 3D estimates of the CME volume and its evolution from white light coronagraphs.…”