Radio Observations of Coronal Mass Ejection Initiation and Development in the Low Solar Corona

Abstract

Coronal mass ejections (CMEs) are large eruptions of plasma and magnetic field from the low solar corona into the heliosphere. These eruptions are often associated with energetic electrons that produce various kinds of radio emission. However, there is ongoing investigation into exactly where, when, and how the electron acceleration occurs during flaring and eruption, and how the associated radio emission can be exploited as a diagnostic of both particle acceleration and CME eruptive physics. Here, we review past and present developments in radio observations of flaring and eruption, from the destabilization of flux ropes to the development of a CME and the eventual driving of shocks in the corona. We concentrate primarily on the progress made in CME radio physics in the past two decades and show how radio imaging spectroscopy provides the ability to diagnose the locations and kinds of electron acceleration during eruption, which provides insight into CME eruptive models in the early stages of their evolution ( < 10 R ⊙ ). We finally discuss how new instrumentation in the radio domain will pave the way for a deeper understanding of CME physics in the near future.

Homologous Accelerated Electron Beams, Quasi-periodic fast-propagating Wave and CME Observed in one Fan-spine Jet

“…Different from the relative stationary radio sources that observed during large-scale solar eruptions (e.g. Carley et al 2020;Chen et al 2021), the fast moving on-disk radio source had a speed of in the range of 4146 to 8414 km s −1 (i.e., ∼ 0.0138c−0.028c), and a height of about 1.46 solar radii above the solar surface. Nearly at the same time (09:08 UT), an interplanetary type III burst was also detected by the NDA and WIND/WAVES, (see Figure 5 (a2) and (a3).…”

Microwave imaging spectroscopy of the solar corona

“…SRH consists of three T-shaped antenna arrays (Fig. 1) operating in the frequency ranges [3][4][5][6][6][7][8][9][10][11][12][12][13][14][15][16][17][18][19][20][21][22][23][24]). Arrays 3-6 are oriented in the east-west-north direction, and arrays 6-12 and 12-24 are oriented in the east-west-south direction.…”

“…Of particular interest is the study of coronal mass ejections (CMEs). MIS is a powerful method to model CME events more adequately [10]. Below, we describe the SRH and give several examples of SRH spectral data.…”

Spatially Resolved Moving Radio Burst Associated with an EUV Wave

“…Over the years, type IV radio bursts have been subcategorized into moving type IV bursts and stationary type IV bursts according to the motion of their source regions (McLean & Aabrum 1985;Pick & Vilmer 2008). Of particular interest are the moving type IV radio bursts, which are commonly believed to be produced by energetic electrons trapped in CMEs via various emission mechanisms (Carley et al 2020). So far, four emission mechanisms have been suggested to interpret the moving type IV radiations, including coherent plasma emission (Duncan 1981;Hariharan et al 2016;Vasanth et al 2019) and electron cyclotron maser emission (Melrose & Dulk 1982;Liu et al 2018), as well as incoherent synchrotron and gyrosynchrotron emission (Kai 1969;Carley et al 2017).…”

“…So far, four emission mechanisms have been suggested to interpret the moving type IV radiations, including coherent plasma emission (Duncan 1981;Hariharan et al 2016;Vasanth et al 2019) and electron cyclotron maser emission (Melrose & Dulk 1982;Liu et al 2018), as well as incoherent synchrotron and gyrosynchrotron emission (Kai 1969;Carley et al 2017). Therefore, if the emission mechanism can be unambiguously determined, moving type IV bursts can provide powerful diagnostics of plasma conditions inside CMEs, such as electron density, characteristics of the electron energy distribution, or magnetic field strength (Pick 2004;Vourlidas 2004;Carley et al 2020).…”