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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

Hill, M. E. and Allen, R. C. and Kollmann, P. and Brown, L. E. and Decker, R. B. and McNutt, R. L. and Krimigis, S. M. and Andrews, G. B. and Bagenal, F. and Clark, G. and Elliott, H. A. and Jaskulek, S. E. and Kusterer, M. B. and Leske, R. A. and Lisse, C. M. and Mewaldt, R. A. and Nelson, K. S. and Richardson, J. D. and Romeo, G. and Salazar, N. A. and Vandegriff, J. D. and Bernardoni, E. A. and Gladstone, G. R. and Horanyi, M. and Linscott, I. R. and Singer, K. N. and Steffl, A. J. and Summers, M. E. and Throop, H. B. and Young, L. A. and Olkin, C. B. and Parker, J. Wm. and Spencer, J. R. and Stern, S. A. and Verbiscer, A. J. and Weaver, H. A. (2020) 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. Astrophysical Journal, 905 (1). Art. No. 69. ISSN 1538-4357. https://resolver.caltech.edu/CaltechAUTHORS:20201215-141038410

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Abstract

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.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/abb408DOIArticle
https://pds.nasa.gov/Related ItemNASA Planetary Data Archive
ORCID:
AuthorORCID
Hill, M. E.0000-0002-5674-4936
Allen, R. C.0000-0003-2079-5683
Kollmann, P.0000-0002-4274-9760
Brown, L. E.0000-0002-9171-0862
Decker, R. B.0000-0002-0655-9863
McNutt, R. L.0000-0002-4722-9166
Krimigis, S. M.0000-0003-2781-2386
Bagenal, F.0000-0002-3963-1614
Clark, G.0000-0002-5264-7194
Elliott, H. A.0000-0003-2297-3922
Leske, R. A.0000-0002-0156-2414
Lisse, C. M.0000-0002-9548-1526
Mewaldt, R. A.0000-0003-2178-9111
Nelson, K. S.0000-0003-3807-4518
Richardson, J. D.0000-0003-4041-7540
Vandegriff, J. D.0000-0002-0781-1565
Gladstone, G. R.0000-0003-0060-072X
Horanyi, M.0000-0002-5920-9226
Singer, K. N.0000-0003-3045-8445
Steffl, A. J.0000-0002-5358-392X
Summers, M. E.0000-0001-5986-8902
Throop, H. B.0000-0002-1988-223X
Young, L. A.0000-0002-7547-3967
Olkin, C. B.0000-0002-5846-716X
Parker, J. Wm.0000-0002-3672-0603
Spencer, J. R.0000-0003-4452-8109
Stern, S. A.0000-0001-5018-7537
Verbiscer, A. J.0000-0002-3323-9304
Weaver, H. A.0000-0003-0951-7762
Additional Information:© 2020. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2019 August 5; revised 2020 August 25; accepted 2020 August 27; published 2020 December 14. The NH work was supported by NASA NH funding through contract NAS5-97271/Task Order 30 and NASA Voyager Interstellar Mission NNN06AA01C. NH/PEPSSI data are publicly available through NASA's planetary data archive (https://pds.nasa.gov). We thank the ACE SWEPAM instrument team and the ACE Science Center (http://www.srl.caltech.edu/ACE/ASC/level2/new/) for providing the solar wind data. We appreciate the efforts of the Voyager MAG team in providing V1 magnetic field measurements (https://omniweb.gsfc.nasa.gov). We acknowledge and thank the network of observers who provided the sunspot number measurements, courtesy of the Royal Observatory of Belgium, Brussels (http://www.sidc.be/silso/home). M.E.H. would like to acknowledge helpful conversations with members of the NASA DRIVE science center, Our Heliospheric Shield, NASA grant 18-DRIVE18_2-0029, 80NSSC20K0603, during the revision stage of this paper.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
NASANAS5-97271
NASANNN06AA01C
NASA18-DRIVE18_2-0029
NASA80NSSC20K0603
Subject Keywords:Interstellar magnetic fields ; Galactic cosmic rays ; Solar wind ; Solar wind termination ; Heliopause ; Heliosheath ; Solar energetic particles ; Cosmic rays ; Forbush effect ; Interplanetary shocks ; Solar cycle ; Cosmic ray detectors
Issue or Number:1
Classification Code: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 effec
Record Number:CaltechAUTHORS:20201215-141038410
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20201215-141038410
Official Citation:M. E. Hill et al 2020 ApJ 905 69
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107102
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:15 Dec 2020 23:38
Last Modified:09 Jun 2021 18:11

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