Sun-Heliosphere Observation-based Ionization Rates Model

Abstract

The solar wind (SW) and the extreme ultraviolet (EUV) radiation modulate fluxes of interstellar and heliospheric particles inside the heliosphere both in time and in space. Understanding this modulation is necessary to correctly interpret measurements of particles of interstellar origin inside the heliosphere. We present a revision of heliospheric ionization rates and provide the Sun-Heliosphere Observation-based Ionization Rates (SHOIR) model based on the currently available data. We calculate the total ionization rates using revised SW and solar EUV data. We study the in-ecliptic variation of the SW parameters, the latitudinal structure of the SW speed and density, and the reconstruction of the photoionization rates. The revision most affects the SW out of the ecliptic plane during solar maximum and the estimation of the photoionization rates, the latter due to a change of the reference data. The revised polar SW is slower and denser during the solar maximum of solar cycle (SC) 24. The current estimated total ionization rates are higher than the previous ones for H, O, and Ne, and lower for He. The changes for the in-ecliptic total ionization rates are less than 10% for H and He, up to 20% for O, and up to 35% for Ne. Additionally, the changes are not constant in time and vary as a function of time and latitude.

arXiv comment24 pages, 14 figures, 2 tables; published in The Astrophysical Journal 897:179 (21pp)

References in corpus (18)

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• Heliolatitude and time variations of solar wind structure from in situ measurements and interplanetary scintillation observations
• Seven Years of Imaging the Global Heliosphere with IBEX
• Survival probability and energy modification of hydrogen Energetic Neutral Atoms on their way from the termination shock to Earth orbit
• Density of neutral interstellar hydrogen at the termination shock from Ulysses pickup ion observations
• Solar parameters for modeling interplanetary background
• Modulation of neutral interstellar He, Ne, O in the heliosphere. Survival probabilities and abundances at IBEX
• The Solar Wind Energy Flux
• Reconstruction of Helio-latitudinal Structure of the Solar Wind Proton Speed and Density
• Interstellar Neutral Gas Species And Their Pickup Ions Inside The Heliospheric Termination Shock. Ionization Rates For H, O, Ne, And He
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• Helium Variation Across Two Solar Cycles Reveals A Speed-Dependent Phase Lag
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• A method for filling gaps in solar irradiance and in solar proxy data
• The energy-dependent position of the IBEX ribbon due to the solar wind structure
• Update of the Solar Lyman-Alpha Profile Line Model
• Solar cycle variation of interstellar neutral He, Ne, O density and pick-up ions along the Earth's orbit
• Determination of the most pertinent EUV proxy for use in thermosphere modeling

Cited by in corpus (14)

• Very Local Interstellar Medium Revealed by Complete Solar Cycle of Interstellar Neutral Helium Observations with IBEX
• A new 3D solar wind speed and density model based on interplanetary scintillation
• WawHelioGlow: a model of the heliospheric backscatter glow. I. Model definition
• 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
• Influence of Heliolatitudinal Anisotropy of Solar FUV/EUV Emissions on Lyman-alpha Helioglow: SOHO/SWAN Observations and WawHelioGlow Modeling
• Backscattered solar Lyman-alpha emission as a tool for the heliospheric boundary exploration
• The flow direction of interstellar neutral H from SOHO/SWAN
• Investigating the IBEX Ribbon Structure a Solar Cycle Apart
• Determining the ionization rates of interstellar neutral species using direct-sampling observations of their direct and indirect beams
• Absorption of the Lyman-$\alpha$ radiation in the heliosphere
• Production and Loss Processes of Hydrogen Energetic Neutral Atoms in the Heliosphere from 5 eV to 500 keV
• Understanding the IBEX ribbon using the kinetic model of pickup proton transport in a scatter-free limit