Imaging the global solar wind flow in EUV

Abstract

[1] We advance the original concept of imaging the three-dimensional solar wind flow (Gruntman, 2001a) by characterizing expected heliospheric EUV signatures under assumptions of a realistic solar wind. Charge exchange collisions between the solar wind alpha particles and heliospheric atomic hydrogen produce unique emissions in the 30.4-nm line. All-sky images at 30.4 nm with high spectral resolution reveal the threedimensional flow properties of the solar wind, including the flow in the regions over the Sun's poles, and the variability of the global solar wind properties during the 11-year solar cycle. We simulate global heliospheric images at 30.4 nm for a realistic threedimensional solar wind with the Sun's effective magnetic dipole tilted with respect to the spin axis, resulting in a complex flow pattern of the plasma. We show that the physical properties of the flow would permit averaging over several rotations of the Sun, thus realistically limiting the total number of all-sky images to a few per year. This feature effectively establishes the sensitivity requirements for an experiment to image the global solar wind.Citation: Gruntman, M., V. Izmodenov, and V.

Heliolatitudinal and time variations of the solar wind mass flux: Inferences from the backscattered solar Lyman‐alpha intensity maps

“…For example, Gruntman [] and Gruntman et al . [] studied theoretically a distribution of EUV emission in the 30.4‐nm line produced in the charge exchange collisions between the solar wind alpha particles and atomic hydrogen in the heliosphere. It was shown in the cited papers of Gruntman that full‐sky images at 30.4‐nm “reveal the three‐dimensional flow properties of the solar wind, including the flow in the regions over the Sun's poles and the variability of the global solar wind properties during the 11‐year solar cycle.” In the paper by Pryor et al [], heliolatitudinal anisotropy of the hydrogen charge exchange rates are studied based on analysis of Ulysses/GAS Lyman‐alpha intensities.…”

“…One way of indirect diagnostic of 3-D solar wind structure is based on observations of heliospheric EUV emission. For example, Gruntman [2001] and Gruntman et al [2006] studied theoretically a distribution of EUV emission in the 30.4-nm line produced in the charge exchange collisions between the solar wind alpha particles and atomic hydrogen in the heliosphere. It was shown in the cited papers of Gruntman that full-sky images at 30.4nm "reveal the three-dimensional flow properties of the solar wind, including the flow in the regions over the Sun's poles and the variability of the global solar wind properties during the 11-year solar cycle."…”

Moon‐based EUV imaging of the Earth's Plasmasphere: Model simulations

“…The third part is the 30.4 nm emissions from other sources, such as interplanetary space and He + born by charge‐exchange collisions [ Gruntman , ] between the solar wind alpha particles (He 2+ ) and the local atomic hydrogen (H) in the magnetosheath. It is known from the literatures that the interplanetary 30.4 nm emission is approximately uniform and extremely low with intensity to be ~0.001 R [ Paresce et al ., ; Jelinsky et al ., ; Gruntman , , ; Gruntman et al ., ]. For the case of solar wind charge exchange (SWCX), the intensity is related to the densities of solar wind He 2+ and local H, the solar wind velocity, and the He 2+ ‐H charge exchange cross section ( σ 30.4 ) which is strongly dependent on collision velocity [ Gruntman , ; Gruntman et al ., ].…”

MHD modeling of the outer heliosphere: Achievements and challenges

“…The heliolongitude and heliolatitude of its northern direction are about 75.76°a nd 82.75°, respectively (for the currently used standard epoch J2000.0, see also Gruntman et al, 2006). A simple calculation shows that the Sun's rotation axis, the LISM velocity vector, and the normal to the ecliptic plane are all lying in approximately the same plane.…”