Strength of the Solar Coronal Magnetic Field – A Comparison of Independent Estimates Using Contemporaneous Radio and White-Light Observations

Kumari, Anshu; Ramesh, R.; Kathiravan, C.; Wang, T. J.

doi:10.1007/s11207-017-1180-6

Cited by 34 publications

(27 citation statements)

References 56 publications

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“…Each file size is ≈ 700 kB. The file sizes are expected to be much higher for digital back end instrumentation based on FPGAs and fast ADCs (see for example Kumari et al (2017); Mugundhan et al (2018)). Hence the necessity of a sophisticated algorithm to classify solar radio radio bursts.…”

Section: Discussionmentioning

confidence: 99%

Automated Detection of Solar Radio Bursts Using a Statistical Method

et al. 2019

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Radio bursts from the solar corona can provide clues to forecast space weather hazards. After recent technology advancements, regular monitoring of radio bursts has increased and large observational data sets are produced. Hence, manual identification and classification of them is a challenging task. In this paper, we describe an algorithm to automatically identify radio bursts from dynamic solar radio spectrograms using a novel statistical method. We used e-CALLISTO radio spectrometer data observed at Gauribidanur observatory near Bangalore in India during 2013 -2014. We have studied the classifier performance using the receiver operating characteristics. Further, we studied type III bursts observed in the year 2014 and found that 75% of the observed bursts were below 200 MHz. Our analysis shows that the positions of the flare sites which are associated with the type III bursts with upper frequency cut-off 200 MHz

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Section: Discussionmentioning

confidence: 99%

Automated Detection of Solar Radio Bursts Using a Statistical Method

et al. 2019

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“…For example, Cho et al (2007) used MK4 coronameter data to constrain the electron density and deduced magnetic field of 1.3-0.4 G at heights of 1.6-2.1 R ⊙ . Similarly, Kumari et al (2017) and Kumari et al (2019) derived the electron density from white light space born coronograph images and reported 0.47-0.44 G at heliocentric 2.61-2.74 R ⊙ and 1.21-0.5 G at heliocentric 1.58-2.15 R ⊙ , respectively. Gopalswamy et al (2012), using additional information on the geometry of the shock from SDO/AIA images, determined the coronal magnetic field to be in the range of 1.3-1.5 G at heliocentric 1.2-1.5 R ⊙ .…”

Section: Type II Burstsmentioning

confidence: 97%

Radio Measurements of the Magnetic Field in the Solar Chromosphere and the Corona

Alissandrakis

Gary

2021

Front. Astron. Space Sci.

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The structure of the upper solar atmosphere, on all observable scales, is intimately governed by the magnetic field. The same holds for a variety of solar phenomena that constitute solar activity, from tiny transient brightening to huge Coronal Mass Ejections. Due to inherent difficulties in measuring magnetic field effects on atoms (Zeeman and Hanle effects) in the corona, radio methods sensitive to electrons are of primary importance in obtaining quantitative information about its magnetic field. In this review we explore these methods and point out their advantages and limitations. After a brief presentation of the magneto-ionic theory of wave propagation in cold, collisionless plasmas, we discuss how the magnetic field affects the radio emission produced by incoherent emission mechanisms (free-free, gyroresonance, and gyrosynchrotron processes) and give examples of measurements of magnetic filed parameters in the quiet sun, active regions and radio CMEs. We proceed by discussing how the inversion of the sense of circular polarization can be used to measure the field above active regions. Subsequently we pass to coherent emission mechanisms and present results of measurements from fiber bursts, zebra patterns, and type II burst emission. We close this review with a discussion of the variation of the magnetic field, deduced by radio measurements, from the low corona up to ~ 10 solar radii and with some thoughts about future work.

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“…In order to understand the shock-driving capability of CMEs, we need to investigate early CME kinematics near the Sun. CMEs leave imprints in different wavelengths, so it is necessary to stitch multiwavelength information for a better understanding of CME behavior (Pick et al, 2006;Vršnak et al, 2006;Zucca et al, 2014;Kumari et al, 2017c;Morosan et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Imaging and Spectral Observations of a Type-II Radio Burst Revealing the Section of the CME-Driven Shock That Accelerates Electrons

et al. 2021

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We report on a multi-wavelength analysis of the 26 January 2014 solar eruption involving a coronal mass ejection (CME) and a Type-II radio burst, performed by combining data from various space and ground-based instruments. An increasing standoff distance with height shows the presence of a strong shock, which further manifests itself in the continuation of the metric Type-II burst into the decameter-hectometric (DH) domain. A plot of speed versus position angle (PA) shows different points on the CME leading edge traveled with different speeds. From the starting frequency of the Type-II burst and white-light data, we find that the shock signature producing the Type-II burst might be coming from the flanks of the CME. Measuring the speeds of the CME flanks, we find the southern flank to be at a higher speed than the northern flank; further the radio contours from Type-II imaging data showed that the burst source was coming from the southern flank of the CME. From the standoff distance at the CME nose, we find that the local Alfven speed is close to the white-light shock speed, thus causing the Mach number to be small there. Also, the presence of a streamer near the southern flank appears to have provided additional favorable conditions for the generation of shock-associated radio emission. These results provide conclusive evidence that the Type-II emission could originate from the flanks of the CME, which in our study is from the southern flank of the CME.

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Strength of the Solar Coronal Magnetic Field – A Comparison of Independent Estimates Using Contemporaneous Radio and White-Light Observations

Cited by 34 publications

References 56 publications

Automated Detection of Solar Radio Bursts Using a Statistical Method

Automated Detection of Solar Radio Bursts Using a Statistical Method

Radio Measurements of the Magnetic Field in the Solar Chromosphere and the Corona

Imaging and Spectral Observations of a Type-II Radio Burst Revealing the Section of the CME-Driven Shock That Accelerates Electrons

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