Figure 1: Solar radio burst 1/e decay (left) times vs. frequency, FWHM source size (center), source position (right) for basic emission. The simulations were carried out for turbulence profile (Figure 2) increased by elements of [1/2, 2] (grey location), and the values of the anisotropy criterion α = [0.19, 0.25, 0.33, 0.42] For information see Kontar et al (2023 ).
Figure 3: Angular broadening of the radio sources (left) and frequency spectrum of density fluctuations P( f) determined at 1au (right). The gray location is predicted from the density variation model in Figure 2.
Solar burst fastest time profiles, source sizes, and positions are figured out generally by proliferation impacts (primarily anisotropic scattering) and not by the intrinsic properties of the radio emission source. An in-depth knowledge of the scattering process paves the way to disentangling scattering results from observations and so better constraining the intrinsic properties of solar radio burst sources. The expanding of extrasolar point sources by the rough solar environment and solar radio burst measurements are complementary data sets (Figure 2).
Based upon a recent paper: Eduard P. Kontar, A. Gordon Emslie, Daniel L. Clarkson, Xingyao Chen, Nicolina Chrysaphi, Francesco Azzollini, Natasha L. S. Jeffrey, Mykola Gordovskyy, An Anisotropic Density Turbulence Model from the Sun to 1 au Derived from Radio Observations, The Astrophysical Journal, Volume 956, Issue 2, id.112. (2023 ): DOI: https://doi.org/10.3847/1538-4357/acf6c1
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Density turbulence in the solar corona and solar wind appears via the properties of solar radio bursts; angular scattering-broadening of extra-solar radio sources observed through the solar atmosphere, and can be measured in-situ in the solar wind. A practical density turbulence model must concurrently explain all 3 kinds of density change observations.
Solar radio bursts (e.g. Type I, II, III) observed below ~ 1 GHz are produced mainly by means of plasma mechanisms at frequencies that are close to either the regional plasma frequency or its double (harmonic), and are thus particularly strongly affected by scattering of radio waves in the corona, so the observed sizes, positions, observed time qualities are “evident” and differ significantly from the emission source attributes. While this provides an obstacle for solar radio observations, it also works as a distinct diagnostic tool to determine how density changes are varying from the Sun to 1 au.
Kontar et al. (2023) have performed a great deal of radio-wave propagation in unstable plasma simulations in between 0.1 RSun and 1au and we consider the lead to light of the very substantial selection of solar observations released in the literature covering the ranges from the low corona to 1 au (Figure 1). Contrast of the observations with simulations allows to deduce the anisotropic density profile (Figure 2).
Figure 1: Solar radio burst 1/e decay (left) times vs. frequency, FWHM source size (center), source position (right) for basic emission. Solar burst quickest time profiles, source sizes, and positions are identified mainly by proliferation effects (mainly anisotropic scattering) and not by the intrinsic homes of the radio emission source. An in-depth knowledge of the scattering procedure paves the way to disentangling scattering impacts from observations and so much better constraining the intrinsic properties of solar radio burst sources. The broadening of extrasolar point sources by the unstable solar atmosphere and solar radio burst measurements are complementary data sets (Figure 2). We note the significant information space between space-based and ground-based solar burst observations in the variety 3– 20 MHz (where extrasolar observations appear necessary), and encourage the development of observations to fill this space and hence more constrain the level of turbulence in the inner heliosphere.
Figure 2: Left: amplitude of the inner-scale density fluctuations utilized to describe the observations in Figure (1 ). The black and red information points correspond to the assumption of essential and harmonic emission, respectively.: As in the left panel, however divided by plasma number density n2.