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Combined ∼10 eV to ∼344 MeV Particle Spectra and Pressures in the Heliosheath along the Voyager 2 Trajectory

Dialynas, Konstantinos and Galli, Andre and Dayeh, Maher A. and Cummings, Alan C. and Decker, Robert B. and Fuselier, Stephen A. and Gkioulidou, Matina and Roussos, Elias and Krimigis, Stamatios M. and Mitchell, Donald G. and Richardson, John D. and Opher, Merav (2020) Combined ∼10 eV to ∼344 MeV Particle Spectra and Pressures in the Heliosheath along the Voyager 2 Trajectory. Astrophysical Journal Letters, 905 (2). Art. No. L24. ISSN 2041-8213. doi:10.3847/2041-8213/abcaaa.

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We report a unique combination of ~10 eV to ~344 MeV in situ ion measurements from the Plasma Science (PLS), Low Energy Charged Particle (LECP), and Cosmic Ray Subsystem (CRS) experiments on the Voyager 2 (V2) spacecraft, and remotely sensed ~110 eV to ~55 keV energetic neutral atom (ENA) measurements from the Interstellar Boundary Explorer (IBEX) mission and Ion and Neutral Camera (INCA) on the Cassini mission. This combination is done over the time period from 2009 to the end of 2016, along the V2 trajectory, toward assessing the properties of the ion energy spectra inside the heliosheath. The combined energy spectra exhibit a series of softening and hardening breaks, providing important insights on the various ion acceleration processes inside the heliosheath. Ions in the <6 keV energy range dominate the total pressure distribution inside the heliosheath but the ion distributions at higher energies (>5.2 keV) provide a significant contribution to the total pressure. With the assumption that all ENAs (~110 eV to 55 keV) are created by charge-exchange interactions inside the heliosheath, we estimate that the magnetic field upstream at the heliopause required to balance the pressure from the heliosheath in the direction of V2 is ~0.67 nT. This number is consistent with the measured magnetic field at V2 from 2018 November, when the spacecraft entered interstellar space.

Item Type:Article
Related URLs:
URLURL TypeDescription
Dialynas, Konstantinos0000-0002-5231-7929
Galli, Andre0000-0003-2425-3793
Dayeh, Maher A.0000-0001-9323-1200
Cummings, Alan C.0000-0002-3840-7696
Decker, Robert B.0000-0002-0655-9863
Fuselier, Stephen A.0000-0003-4101-7901
Gkioulidou, Matina0000-0001-9979-2164
Roussos, Elias0000-0002-5699-0678
Krimigis, Stamatios M.0000-0003-2781-2386
Mitchell, Donald G.0000-0003-1960-2119
Richardson, John D.0000-0003-4041-7540
Opher, Merav0000-0002-8767-8273
Additional Information:© 2020. The American Astronomical Society. Received 2020 October 19; revised 2020 November 13; accepted 2020 November 16; published 2020 December 21. This work was supported by the NASA Drive Science Centers initiative, under contract 80NSSC20K0603-18-DRIVE18_2-0029 in BU SHIELD DRIVE Science Center ( The authors are grateful to all Cassini/MIMI, Voyager/LECP/PLS/CRS, and IBEX team members for useful discussions that made this work possible. The work at JHU/APL was supported also by NASA under contracts NAS5 97271, NNX07AJ69G, and NNN06AA01C and by subcontract at the Office for Space Research and Technology. The work at Caltech was supported by NASA award NNN12AA01C. J.D.R. was supported by NASA contract 959203 from JPL to MIT and NASA HGI 80NSSC19K0260.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
NASANAS5 97271
Subject Keywords:Heliosphere ; Heliopause ; Heliosheath ; Termination shock ; Interstellar medium ; Interstellar magnetic fields
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Heliosphere (711); Heliopause (707); Heliosheath (710); Termination shock (1690); Interstellar medium (847); Interstellar magnetic fields (845)
Record Number:CaltechAUTHORS:20201224-085807017
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107274
Deposited By: George Porter
Deposited On:04 Jan 2021 15:04
Last Modified:16 Nov 2021 19:01

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