Interstellar Neutral Helium in the Heliosphere from IBEX Observations. VI. The He+ Density and the Ionization State in the Very Local Interstellar Matter

M. Bzowski; A. Czechowski; P. C. Frisch; S. A. Fuselier; A. Galli; J. Grygorczuk; J. Heerikhuisen; M. A. Kubiak; H. Kucharek; D. J. McComas; E. Möbius; N. A. Schwadron; J. Slavin; J. M. Sokół; P. Swaczyna; P. Wurz; E. J. Zirnstein

doi:10.3847/1538-4357/ab3462

Interstellar Neutral Helium in the Heliosphere from IBEX Observations. VI. The He⁺ Density and the Ionization State in the Very Local Interstellar Matter

M. Bzowski, A. Czechowski, P. C. Frisch, S. A. Fuselier, A. Galli, J. Grygorczuk, J. Heerikhuisen, M. A. Kubiak, H. Kucharek, D. J. McComas, E. Möbius, N. A. Schwadron, J. Slavin, J. M. Sokół, P. Swaczyna, P. Wurz, E. J. Zirnstein

Astrophysical Sciences

Research output: Contribution to journal › Article › peer-review

40 Scopus citations

Abstract

Interstellar neutral gas atoms penetrate the heliopause and reach 1 au, where they are detected by Interstellar Boundary Explorer (IBEX). The flow of neutral interstellar helium through the perturbed interstellar plasma in the outer heliosheath (OHS) results in the creation of a secondary population of interstellar He atoms, the so-called Warm Breeze, due to charge exchange with perturbed ions. The secondary population brings the imprint of the OHS conditions to the IBEX-Lo instrument. Based on a global simulation of the heliosphere with measurement-based parameters and detailed kinetic simulation of the filtration of He in the OHS, we find the number density of the interstellar He⁺ population to be (8.98 0.12) 10^-3 cm^-3. With this, we obtain the absolute density of interstellar H⁺ as 5.4 10^-2 cm^-3 and that of electrons as 6.3 10^-2 cm^-3, with ionization degrees of 0.26 for H and 0.37 for He. The results agree with estimates of the parameters of the Very Local Interstellar Matter obtained from fitting the observed spectra of diffuse interstellar EUV and the soft X-ray background.

Original language	English (US)
Article number	60
Journal	Astrophysical Journal
Volume	882
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/ab3462
State	Published - Sep 1 2019

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Keywords

ISM: abundances
ISM: atoms
ISM: clouds
ISM: magnetic fields
Sun: heliosphere
local interstellar matter

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10.3847/1538-4357/ab3462

Cite this

Bzowski, M., Czechowski, A., Frisch, P. C., Fuselier, S. A., Galli, A., Grygorczuk, J., Heerikhuisen, J., Kubiak, M. A., Kucharek, H., McComas, D. J., Möbius, E., Schwadron, N. A., Slavin, J., Sokół, J. M., Swaczyna, P., Wurz, P., & Zirnstein, E. J. (2019). Interstellar Neutral Helium in the Heliosphere from IBEX Observations. VI. The He⁺ Density and the Ionization State in the Very Local Interstellar Matter. Astrophysical Journal, 882(1), Article 60. https://doi.org/10.3847/1538-4357/ab3462

@article{3af78085074a4cd39a895168a7121661,

title = "Interstellar Neutral Helium in the Heliosphere from IBEX Observations. VI. The He+ Density and the Ionization State in the Very Local Interstellar Matter",

abstract = "Interstellar neutral gas atoms penetrate the heliopause and reach 1 au, where they are detected by Interstellar Boundary Explorer (IBEX). The flow of neutral interstellar helium through the perturbed interstellar plasma in the outer heliosheath (OHS) results in the creation of a secondary population of interstellar He atoms, the so-called Warm Breeze, due to charge exchange with perturbed ions. The secondary population brings the imprint of the OHS conditions to the IBEX-Lo instrument. Based on a global simulation of the heliosphere with measurement-based parameters and detailed kinetic simulation of the filtration of He in the OHS, we find the number density of the interstellar He+ population to be (8.98 0.12) 10-3 cm-3. With this, we obtain the absolute density of interstellar H+ as 5.4 10-2 cm-3 and that of electrons as 6.3 10-2 cm-3, with ionization degrees of 0.26 for H and 0.37 for He. The results agree with estimates of the parameters of the Very Local Interstellar Matter obtained from fitting the observed spectra of diffuse interstellar EUV and the soft X-ray background.",

keywords = "ISM: abundances, ISM: atoms, ISM: clouds, ISM: magnetic fields, Sun: heliosphere, local interstellar matter",

author = "M. Bzowski and A. Czechowski and Frisch, {P. C.} and Fuselier, {S. A.} and A. Galli and J. Grygorczuk and J. Heerikhuisen and Kubiak, {M. A.} and H. Kucharek and McComas, {D. J.} and E. M{\"o}bius and Schwadron, {N. A.} and J. Slavin and Sok{\'o}{\l}, {J. M.} and P. Swaczyna and P. Wurz and Zirnstein, {E. J.}",

year = "2019",

month = sep,

day = "1",

doi = "10.3847/1538-4357/ab3462",

language = "English (US)",

volume = "882",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

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Bzowski, M, Czechowski, A, Frisch, PC, Fuselier, SA, Galli, A, Grygorczuk, J, Heerikhuisen, J, Kubiak, MA, Kucharek, H, McComas, DJ, Möbius, E, Schwadron, NA, Slavin, J, Sokół, JM, Swaczyna, P, Wurz, P & Zirnstein, EJ 2019, 'Interstellar Neutral Helium in the Heliosphere from IBEX Observations. VI. The He⁺ Density and the Ionization State in the Very Local Interstellar Matter', Astrophysical Journal, vol. 882, no. 1, 60. https://doi.org/10.3847/1538-4357/ab3462

TY - JOUR

T1 - Interstellar Neutral Helium in the Heliosphere from IBEX Observations. VI. The He+ Density and the Ionization State in the Very Local Interstellar Matter

AU - Bzowski, M.

AU - Czechowski, A.

AU - Frisch, P. C.

AU - Fuselier, S. A.

AU - Galli, A.

AU - Grygorczuk, J.

AU - Heerikhuisen, J.

AU - Kubiak, M. A.

AU - Kucharek, H.

AU - McComas, D. J.

AU - Möbius, E.

AU - Schwadron, N. A.

AU - Slavin, J.

AU - Sokół, J. M.

AU - Swaczyna, P.

AU - Wurz, P.

AU - Zirnstein, E. J.

PY - 2019/9/1

Y1 - 2019/9/1

N2 - Interstellar neutral gas atoms penetrate the heliopause and reach 1 au, where they are detected by Interstellar Boundary Explorer (IBEX). The flow of neutral interstellar helium through the perturbed interstellar plasma in the outer heliosheath (OHS) results in the creation of a secondary population of interstellar He atoms, the so-called Warm Breeze, due to charge exchange with perturbed ions. The secondary population brings the imprint of the OHS conditions to the IBEX-Lo instrument. Based on a global simulation of the heliosphere with measurement-based parameters and detailed kinetic simulation of the filtration of He in the OHS, we find the number density of the interstellar He+ population to be (8.98 0.12) 10-3 cm-3. With this, we obtain the absolute density of interstellar H+ as 5.4 10-2 cm-3 and that of electrons as 6.3 10-2 cm-3, with ionization degrees of 0.26 for H and 0.37 for He. The results agree with estimates of the parameters of the Very Local Interstellar Matter obtained from fitting the observed spectra of diffuse interstellar EUV and the soft X-ray background.

AB - Interstellar neutral gas atoms penetrate the heliopause and reach 1 au, where they are detected by Interstellar Boundary Explorer (IBEX). The flow of neutral interstellar helium through the perturbed interstellar plasma in the outer heliosheath (OHS) results in the creation of a secondary population of interstellar He atoms, the so-called Warm Breeze, due to charge exchange with perturbed ions. The secondary population brings the imprint of the OHS conditions to the IBEX-Lo instrument. Based on a global simulation of the heliosphere with measurement-based parameters and detailed kinetic simulation of the filtration of He in the OHS, we find the number density of the interstellar He+ population to be (8.98 0.12) 10-3 cm-3. With this, we obtain the absolute density of interstellar H+ as 5.4 10-2 cm-3 and that of electrons as 6.3 10-2 cm-3, with ionization degrees of 0.26 for H and 0.37 for He. The results agree with estimates of the parameters of the Very Local Interstellar Matter obtained from fitting the observed spectra of diffuse interstellar EUV and the soft X-ray background.

KW - ISM: abundances

KW - ISM: atoms

KW - ISM: clouds

KW - ISM: magnetic fields

KW - Sun: heliosphere

KW - local interstellar matter

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DO - 10.3847/1538-4357/ab3462

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