Interstellar Neutral Gas Species And Their Pickup Ions Inside The Heliospheric Termination Shock. The Large-scale Structures

Abstract

We study the distribution of the interstellar neutral (ISN) gas density and the pick-up ion (PUI) density of hydrogen, helium, neon, and oxygen in the heliosphere for heliocentric distances from inside 1 au up to the solar wind termination shock (TS), both in and out of the ecliptic plane. We discuss similarities and differences in the large-scale structures of the ISN gas and PUIs formed in the heliosphere between various species. We discuss the distribution of ISN gas and PUI densities for two extreme phases of the solar activity cycle, it is the solar minimum and the solar maximum. We identify the location of the ISN gas density cavity of various species. We study the relative abundance ratios of Ne/O, H/He, Ne/He, and O/He for ISN gas and PUIs densities and their variation with location in the heliosphere. We also discuss the modulation of relative abundance ratios of ISN gas and PUIs along the TS. We conclude that the preferable locations for detection of He${}^{+}$ and Ne${}^{+}$ PUIs are in the downwind hemisphere within 1~au, whereas for H${}^{+}$ and O${}^{+}$ PUIs the preferable locations for detection are for distances from Jupiter to Pluto orbits.

18 figures, 2 tables, Published in The Astrophysical Journal

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• A new 3D solar wind speed and density model based on interplanetary scintillation
• Update of the Solar Lyman-Alpha Profile Line Model
• Science Opportunities from Observations of the Interstellar Neutral Gas with Adjustable Boresight Direction
• On general correlation between 3D solar wind speed and density model and solar proxies
• WawHelioGlow: a model of the heliospheric backscatter glow. II. The helioglow buildup and the potential significance of the anisotropy in the solar EUV output
• Interstellar Neutral Hydrogen in the Heliosphere: New Horizons Observations in the Context of Models
• Heliospheric structure as revealed by the 3 -- 88 keV H ENA spectra
• Influence of Heliolatitudinal Anisotropy of Solar FUV/EUV Emissions on Lyman-alpha Helioglow: SOHO/SWAN Observations and WawHelioGlow Modeling
• Relative In-flight Response of IBEX-Lo to Interstellar Neutral Helium Atoms
• Production and Loss Processes of Hydrogen Energetic Neutral Atoms in the Heliosphere from 5 eV to 500 keV