We use Ulysses observations of plasma parameters at $0 ^ circ$ to $80 ^ circ$ latitudes. The figure reveals resemblances between Ulysses observations at high latitudes ($ gtrsim 40 ^ circ$) and PUI design forecasts at $45 ^ circ$ latitude in radial profiles of the solar wind density, speed, and radial and azimuthal magnetic field components.
Figure 2 (top) shows that the estimated $C_N ^ 2$ (using two different techniques: explained as design 1 and design 2) for the high latitude fast wind PUI design is much smaller sized than the $C_N ^ 2$ calculated in the ecliptic aircraft utilizing V2 observations. ^ 2$ is much larger in the ecliptic plane than that in the high latitude area. The vertical cyan broken line shows the area of the HTS utilizing the V2 data while the green rushed line determines the presumed HTS location at high $45 ^ circ$ latitudes.
We examine angular expanding of radio wave scattering by density abnormalities in the external heliosphere and the really regional interstellar medium (VLISM), integrating an inner scale, latitudinal, and radial dependencies for the density change spectra and radiation propagation courses both near and out of the ecliptic airplane.
Outer Heliospheric Radio Emission
Low-frequency radio wave emission was discovered in the far-off heliosphere by the Voyager objectives.
Pickup Ion (PUI)- moderated high latitude quick Solar Wind vs Voyager Data in the Ecliptic Plane.
The pickup ion (PUI)- moderated solar wind and the MHD turbulence transportation design of Zank et al., 2018, that describes background solar wind, turbulence, and PUI properties from 1 AU to 84 AU, is utilized to examine density turbulence throughout the heliosphere. An easy scaling extends the theoretical predictions of the PUI model to the high latitude wind beyond the heliospheric termination shock (HTS). The near ecliptic solar wind and turbulence quantities are determined utilizing plasma and magnetometer information from the Voyager 2 (V2) spacecraft over the duration 1977 to 2018. We observe obvious distinctions in the high latitude and V2 plasma and magnetic field variables.
Figure 1– Plots reveal (a) density, (b) solar wind speed, (c) proton temperature, (d) azimuthal magnetic field, (e) radial electromagnetic field, and (f) heliolatitude with increasing heliocentric range over the period March 1, 1995 to March 31, 1996..
To check the consistency of the PUI design predictions, in Figure 1 we compare, the theoretical plasma criteria and magnetic field elements obtained at $45 ^ circ$ latitude with the Ulysses observations. We use Ulysses observations of plasma parameters at $0 ^ circ$ to $80 ^ circ$ latitudes. The figure shows resemblances between Ulysses observations at high latitudes ($ gtrsim 40 ^ circ$) and PUI model predictions at $45 ^ circ$ latitude in radial profiles of the solar wind density, speed, and radial and azimuthal magnetic field components.
Inner Scale and Density Turbulence Amplitude.
We apply the parabolic wave formula (PWE) theory to compute the angular expanding of the radio waves due to scattering by density abnormalities.
The essential in the above equation is numerically solved for the density turbulence designs. Based upon the turbulence designs and observations, we calculate the scattering angle of the radio sources in the high latitude and near ecliptic wind. We compare the mathematical results with the analytic predictions from Cairns 1995 and the observed source sizes. In addition, Figure 2 (bottom) compares the predictions of $theta _ $ for the PUI-mediated high latitude solar wind with the obvious source size from Voyager 1 and 2 observations, discovering great contract between the observations and the theoretical predictions at high latitudes..
Conclusions.
To summarize, our examination offers an extended description of the angular expanding of outer heliospheric radio frequency radio waves, addressing three vital aspects: i) the inner scale, ii) the radially differing difference of density variations that results in various radial profiles in the solar wind beyond 1 AU, and most significantly, iii) the contribution of the high latitude quick solar wind.
Based on recent paper by Tasnim et al., Density Turbulence and the Angular Broadening of Outer Heliospheric Radio Sources at High Latitudes and in the Ecliptic Plane, The Astrophysical Journal, 928, id.125, DOI: 10.3847/ 1538-4357/ ac5031.
References.
Armstrong, J. W., Coles, W. A., Rickett, B. J., J. Geophys. Res. 105 (2000 ): 5149-5156.
Cairns, I. Geophys. 22, no. 24 (1995 ): 3433-3436.
Gurnett, D. A., Allendorf, S. C., Kurth, W. S. Geophys. Res.
Tasnim, S., Zank, G. P., Cairns, I. H., et al. Journal of Physics: Conference Series 1620, no. 1 (2020 ).
Zank, G. P., Adhikari, L., Zhao, L. -L., et al. Astrophys. J. 869, no. 1 (2018 ).
* Full list of authors: Samira Tasnim, Gary. P. Zank, Iver H. Cairns, and L. Adhikari.
