The Heliosphere and Local Interstellar Medium from Neutral Atom Observations at Energies Below 10 keV

Galli, André; Baliukin, Igor; Bzowski, M.; Izmodenov, Vladislav; Kornbleuth, Marc; Kucharek, H.; Möbius, E.; Opher, M.; Reisenfeld, D. B.; Schwadron, N. A.; Swaczyna, P.

doi:10.1007/s11214-022-00901-7

“…Kleimann et al [2022] presents an overview of the current state of research in global modelling of the heliospheric interface. Galli et al [2022] summarizes all direct observations of interstellar H atoms (and other neutrals), most of which were acquired with the Interstellar Boundary Explorer (IBEX) launched in 2008.…”

Section: Lyman-α Emissionmentioning

confidence: 99%

“…3. The third population, which we refer to as the hot component, is created by charge exchange of the core solar wind protons and pickup protons in the inner heliosheath (so-called energetic neutral atoms, ENAs), where the solar wind is decelerated to subsonic speed and the local plasma temperature of the order 10 5 -10 6 K [see also Sokol et al, 2022;Galli et al, 2022]. It is seen in Figure 3, that the hot component produces a very broad spectrum, and its peak emission is two orders of magnitude lower than the peak value of the total line.…”

Section: New Horizons/alicementioning

confidence: 99%

Backscattered Solar Lyman-$\alpha $ Emission as a Tool for the Heliospheric Boundary Exploration

Baliukin

¹

,

Bertaux

²

,

Bzowski

³

et al. 2022

Self Cite

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This review summarizes our current understanding of the outer heliosphere and local interstellar medium (LISM) inferred from observations and modeling of interplanetary Lyman-α emission. The emission is produced by solar Lyman-α photons (121.567 nm) backscattered by interstellar H atoms inflowing to the heliosphere from the LISM. Studies of Lyman-α radiation determined the parameters of interstellar hydrogen within a few astronomical units from the Sun. The interstellar hydrogen atoms appeared to be decelerated, heated, and shifted compared to the helium atoms. The detected deceleration and heating proved the existence of secondary hydrogen atoms created near the heliopause. This finding supports the discovery of a Hydrogen Wall beyond the heliosphere consisting of heated hydrogen observed in HST/GHRS Lyman-α absorption spectra toward nearby stars. The shift of the interstellar hydrogen bulk velocity was the first observational evidence of the global heliosphere asymme-

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“…The VLISM turbulence and the instability process of PUI distributions are both key ingredients of the existing theories for the formation of the IBEX "ribbon" of enhanced ENAs, as discussed in Sec. 3.2.3 of Galli et al (2022) in this volume.…”

Section: Microinstability Of Pui Distributions and The Ibex Ribbonmentioning

confidence: 92%

Turbulence in the outer heliosphere

Fraternale¹,

Adhikari²,

Fichtner³

et al. 2022

Preprint

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The solar wind (SW) and local interstellar medium (LISM) are turbulent media. Their interaction is governed by complex physical processes and creates heliospheric regions with significantly different properties in terms of particle populations, bulk flow and turbulence. Our knowledge of the solar wind turbulence nature and dynamics mostly relies on near-Earth and near-Sun observations, and has been increasingly improving in recent years due to the availability of a wealth of space missions, including multi-spacecraft missions. In contrast, the properties of turbulence in the outer heliosphere are still not completely understood. In situ observations by Voyager and New Horizons, and remote neutral atom measurements by IBEX strongly suggest that turbulence is one of the critical processes acting at the heliospheric interface. It is intimately connected to charge exchange processes responsible for the production of suprathermal ions and energetic neutral atoms. This paper reviews the observational evidence of turbulence in the distant SW and in the LISM, advances in modeling efforts, and open challenges.Keywords Turbulence • Solar wind • Interstellar medium • Heliosphere 1 Some definitions and nomenclature that will be used throughout in this paper are given: the Elsässer energies (Z ± ) 2 = z ± 2 /2, total turbulence energy density,Alfvén ratio r A = Eu/E b . Eu = δu 2 /2 and E b = δB 2 /(µ 0 ρ)/2 are the turbulent kinetic energy and magnetic energy densities in Alfvén units, respectively.

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“…The VLISM turbulence and the instability process of PUI distributions are both key ingredients of the existing theories for the formation of the IBEX "ribbon" of enhanced ENAs, as discussed in Sect. 3.2.3 of Galli et al (2022) in this journal.…”

Section: Microinstability Of Pui Distributions and The Ibex Ribbonmentioning

confidence: 97%

Turbulence in the Outer Heliosphere

Fraternale

¹

,

Adhikari

²

,

Fichtner

³

et al. 2022

View full text Add to dashboard Cite

The solar wind (SW) and local interstellar medium (LISM) are turbulent media. Their interaction is governed by complex physical processes and creates heliospheric regions with significantly different properties in terms of particle populations, bulk flow and turbulence. Our knowledge of the solar wind turbulence nature and dynamics mostly relies on near-Earth and near-Sun observations, and has been increasingly improving in recent years due to the availability of a wealth of space missions, including multi-spacecraft missions. In contrast, the properties of turbulence in the outer heliosphere are still not completely understood. In situ observations by Voyager and New Horizons, and remote neutral atom measurements by IBEX strongly suggest that turbulence is one of the critical processes acting at the heliospheric interface. It is intimately connected to charge exchange processes responsible for the production of suprathermal ions and energetic neutral atoms. This paper reviews the observational evidence of turbulence in the distant SW and in the LISM, advances in modeling efforts, and open challenges.

show abstract

The Heliosphere and Local Interstellar Medium from Neutral Atom Observations at Energies Below 10 keV

Cited by 22 publications

References 180 publications

Backscattered Solar Lyman-$\alpha $ Emission as a Tool for the Heliospheric Boundary Exploration

Backscattered Solar Lyman-$\alpha $ Emission as a Tool for the Heliospheric Boundary Exploration

Turbulence in the outer heliosphere

Turbulence in the Outer Heliosphere

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