Pluto's Interaction With Energetic Heliospheric Ions

Kollmann, P.; Hill, M. E.; Allen, R. C.; McNutt, R. L.; Brown, L. E.; Barnes, N. P.; Delamere, P. A.; Clark, G.; Andrews, G. B.; Salazar, N.; Westlake, J. H.; Romeo, G.; Vandegriff, J. D.; Kusterer, M. B.; Smith, Daniel C.; Nelson, K. S.; Jaskulek, S.; Decker, R. B.; Cheng, A. F.; Krimigis, S. M.; Lisse, C. M.; Mitchell, D. G.; Weaver, H. A.; Elliott, H. A.; Fattig, E.; Gladstone, G. Randall; Valek, P. W.; Weidner, S.; Kammer, Joshua A.; Bagenal, F.; Horányi, M.; Kaufmann, D. E.; Harch, A.; Olkin, C. B.; Piquette, M.; Spencer, J. R.; Young, L. A.; Ennico, K.; Summers, M. E.; Stern, S. A.

doi:10.1029/2019ja026830

Cited by 4 publications

(1 citation statement)

References 43 publications

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“…Smaller features in the GCR modulation can also be associated with shocks. One example (shown in Figure 2) occurred in the NH observations on day of year (DOY) 278 of 2015 (2015 October 5), not long after the NH Pluto flyby on DOY 195 (2015 July 14) (Bagenal et al 2016;Kollmann et al 2019aKollmann et al , 2019b. The bottom two panels in Figure 2 show lower-energy, local populations; the observations in Figure 2(d) are dominated by helium, mostly pickup ions and suprathermal particles (Kollmann et al 2019a), down to ∼2 keV nuc −1 , and Figure 2(e) shows energetic protons (from 20 to 800 keV).…”

Section: Cosmic Rays In the Supersonic Solar Wind And Heliosheathmentioning

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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Section: Cosmic Rays In the Supersonic Solar Wind And Heliosheathmentioning

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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Future Exploration of the Outer Heliosphere and Very Local Interstellar Medium by Interstellar Probe

et al. 2023

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A detailed overview of the knowledge gaps in our understanding of the heliospheric interaction with the largely unexplored Very Local Interstellar Medium (VLISM) are provided along with predictions of with the scientific discoveries that await. The new measurements required to make progress in this expanding frontier of space physics are discussed and include in-situ plasma and pick-up ion measurements throughout the heliosheath, direct sampling of the VLISM properties such as elemental and isotopic composition, densities, flows, and temperatures of neutral gas, dust and plasma, and remote energetic neutral atom (ENA) and Lyman-alpha (LYA) imaging from vantage points that can uniquely discern the heliospheric shape and bring new information on the interaction with interstellar hydrogen. The implementation of a pragmatic Interstellar Probe mission with a nominal design life to reach 375 Astronomical Units (au) with likely operation out to 550 au are reported as a result of a 4-year NASA funded mission study.

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Pluto's Interaction With Energetic Heliospheric Ions

et al. 2019

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Pluto energies of a few kiloelectron volts and suprathermal ions with tens of kiloelectron volts and above. We measure this population using the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument on board the New Horizons spacecraft that flew by Pluto in 2015. Even though the measured ions have gyroradii larger than the size of Pluto and the cross section of its magnetosphere, we find that the boundary of the magnetosphere is depleting the energetic ion intensities by about an order of magnitude close to Pluto. The intensity is increasing exponentially with distance to Pluto and reaches nominal levels of the interplanetary medium at about 190RP distance. Inside the wake of Pluto, we observe oscillations of the ion intensities with a periodicity of about 0.2 hr. We show that these can be quantitatively explained by the electric field of an ultralow‐frequency wave and discuss possible physical drivers for such a field. We find no evidence for the presence of plutogenic ions in the considered energy range.

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Pluto's Interaction With Energetic Heliospheric Ions

Cited by 4 publications

References 43 publications

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

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

Future Exploration of the Outer Heliosphere and Very Local Interstellar Medium by Interstellar Probe

Pluto's Interaction With Energetic Heliospheric Ions

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