Energetic charged particle measurements from Voyager 2 at the heliopause and beyond

Krimigis, S. M.; Decker, R. B.; Roelof, E. C.; Hill, M. E.; Bostrom, C. O.; Dialynas, K.; Gloeckler, G.; Hamilton, D. C.; Keath, E. P.; Lanzerotti, L. J.

doi:10.1038/s41550-019-0927-4

Cited by 76 publications

(84 citation statements)

References 41 publications

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“…We find that the average value of W R , W R , is about 69.4 W m −2 with a total uncertainty of at most 20%, which is similar to previous results based on long-term observations at greater distances and various latitudes (e.g., Schwenn & Marsch 1990;Meyer-Vernet 2006;Le Chat et al 2009McComas et al 2014). This result confirms that this quantity appears as a global solar constant, which is of importance since it is often used to deduce the solar wind density from the speed (or the reverse) in global heliospheric studies and modeling (e.g., Shen et al 2018;McComas et al 2014;McComas et al 2017McComas et al , 2020Krimigis et al 2019;Wang et al 2020).…”

Section: Discussionsupporting

confidence: 88%

Solar wind energy flux observations in the inner heliosphere: first results from Parker Solar Probe

Liu

Issautier

Meyer‐Vernet

et al. 2021

A&A

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Aims. We investigate the solar wind energy flux in the inner heliosphere using 12-day observations around each perihelion of Encounter One (E01), Two (E02), Four (E04), and Five (E05) of Parker Solar Probe (PSP), respectively, with a minimum heliocentric distance of 27.8 solar radii (R⊙). Methods. Energy flux was calculated based on electron parameters (density ne, core electron temperature Tc, and suprathermal electron temperature Th) obtained from the simplified analysis of the plasma quasi-thermal noise (QTN) spectrum measured by RFS/FIELDS and the bulk proton parameters (bulk speed Vp and temperature Tp) measured by the Faraday Cup onboard PSP, SPC/SWEAP. Results. Combining observations from E01, E02, E04, and E05, the averaged energy flux value normalized to 1 R⊙ plus the energy necessary to overcome the solar gravitation (WR⊙) is about 70 ± 14 W m−2, which is similar to the average value (79 ± 18 W m−2) derived by Le Chat, G., Issautier, K., & Meyer-Vernet, N. (2012, Sol. Phys., 279, 197) from 24-yr observations by Helios, Ulysses, and Wind at various distances and heliolatitudes. It is remarkable that the distributions of WR⊙ are nearly symmetrical and well fitted by Gaussians, much more so than at 1 AU, which may imply that the small heliocentric distance limits the interactions with transient plasma structures.

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Section: Discussionsupporting

confidence: 88%

Solar wind energy flux observations in the inner heliosphere: first results from Parker Solar Probe

Liu

Issautier

Meyer‐Vernet

et al. 2021

A&A

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“…The V1 and V2 spacecraft have been in flight since 1977 and have moved steadily outward. As of the end of 2018, both spacecraft have entered local interstellar space (Burlaga et al 2019;Gurnett & Kurth 2019;Krimigis et al 2019;Richardson & Belcher 2019;Stone et al 2019), but we will not discuss any V2 interstellar observations herein. Two instruments on each…”

Section: Ace and Voyager Cosmic Ray Measurementsmentioning

confidence: 99%

Influence of Solar Disturbances on Galactic Cosmic Rays in the Solar Wind, Heliosheath, and Local Interstellar Medium: Advanced Composition Explorer, New Horizons, and Voyager Observations

Hill¹,

Allen²,

Kollmann³

et al. 2020

ApJ

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We augment the heliospheric network of galactic cosmic ray (GCR) monitors using 2012-2017 penetrating radiation measurements from the New Horizons (NH) Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI), obtaining intensities of 75 MeV particles. The new, predominantly GCR observations provide critical links between the Sun andVoyager 2 and Voyager 1 (V2 and V1), in the heliosheath and local interstellar medium (LISM), respectively. We provide NH, Advanced Composition Explorer (ACE), V2, and V1 GCR observations, using them to track solar cycle variations and short-term Forbush decreases from the Sun to the LISM, and to examine the interaction that results in the surprising, previously reported V1 LISM anisotropy episodes. To investigate these episodes and the hitherto unexplained lagging of associated in situ shock features at V1, propagating disturbances seen at ACE, NH, and V2 were compared to V1. We conclude that the region where LISM magnetic field lines drape around the heliopause is likely critical for communicating solar disturbance signals upstream of the heliosheath to V1. We propose that the anisotropy-causing physical process that suppresses intensities at ∼90°pitch angles relies on GCRs escaping from a single compression in the draping region,not on GCRs trapped between two compressions. We also show that NH suprathermal and energetic particle data from PEPSSI are consistent with the interpretation that traveling shocks and corotating interaction region (CIR) remnants can be distinguished by the existence or lack of Forbush decreases, respectively, because turbulent magnetic fields at local shocks inhibit GCR transport while older CIR structures reaching the outer heliosphere do not. Unified Astronomy Thesaurus concepts: Interstellar magnetic fields (845); Galactic cosmic rays (567); Solar wind (1534); Solar wind termination (1535); Heliopause (707); Heliosheath (710); Solar energetic particles (1491); Cosmic rays (329); Forbush effect (546); Interplanetary shocks (829); Solar cycle (1487); Cosmic ray detectors (325)

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“…However, based on IBEX observations, it is also suggested that the contributions from the IS flow and magnetic field are comparable (Fuselier & Cairns 2013;Schwadron et al 2014). Both V1 and V2 crossings from the HP showed prominent similarities and intriguing differences (e.g., Table 1 of Krimigis et al 2019).…”

Section: Introductionmentioning

confidence: 98%

“…The V1 and V2 crossings of the HP, in 2012 (Krimigis et al 2013;Stone et al 2013;Burlaga et al 2013;Gurnett et al 2013) and 2018 (Krimigis et al 2019;Stone et al 2019;Richardson et al 2019;Gurnett & Kurth 2019;Burlaga et al 2019) at ∼122 au and ∼119 au, respectively, provided invaluable information on the extent of the upwind heliosphere's expansion into the LISM and the properties of the upstream medium, showing that the interstellar (IS) flow is not the primary driver of the interaction of the heliosphere with the LISM. The pressure of the IS magnetic field is mainly responsible for configuring the HS, as was initially suggested in Krimigis et al (2009) and Dialynas et al (2017a).…”

Section: Introductionmentioning

confidence: 99%

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

Dialynas

Galli

Dayeh

et al. 2020

ApJL

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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.

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Energetic charged particle measurements from Voyager 2 at the heliopause and beyond

Cited by 76 publications

References 41 publications

Solar wind energy flux observations in the inner heliosphere: first results from Parker Solar Probe

Solar wind energy flux observations in the inner heliosphere: first results from Parker Solar Probe

Influence of Solar Disturbances on Galactic Cosmic Rays in the Solar Wind, Heliosheath, and Local Interstellar Medium: Advanced Composition Explorer, New Horizons, and Voyager Observations

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

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