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Richardson JD, Burlaga LF, Elliott H, Kurth WS, Liu YD, von Steiger R. Observations of the Outer Heliosphere, Heliosheath, and Interstellar Medium. SPACE SCIENCE REVIEWS 2022; 218:35. [PMID: 35664862 DOI: 10.1007/s11214-006-9023-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/14/2022] [Indexed: 05/23/2023]
Abstract
The Voyager spacecraft have left the heliosphere and entered the interstellar medium, making the first observations of the termination shock, heliosheath, and heliopause. New Horizons is observing the solar wind in the outer heliosphere and making the first direct observations of solar wind pickup ions. This paper reviews the observations of the solar wind plasma and magnetic fields throughout the heliosphere and in the interstellar medium.
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Affiliation(s)
- J D Richardson
- Kavli Institute for Astrophysics and Space Research and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA USA
| | - L F Burlaga
- NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 USA
| | - H Elliott
- Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 USA
| | - W S Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
| | - Y D Liu
- State Key Laboratory for Space Weather, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - R von Steiger
- Universität Bern, Bern, 2 Switzerland
- International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
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Richardson JD, Burlaga LF, Elliott H, Kurth WS, Liu YD, von Steiger R. Observations of the Outer Heliosphere, Heliosheath, and Interstellar Medium. SPACE SCIENCE REVIEWS 2022; 218:35. [PMID: 35664862 DOI: 10.1007/s11214-011-9825-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/14/2022] [Indexed: 05/23/2023]
Abstract
The Voyager spacecraft have left the heliosphere and entered the interstellar medium, making the first observations of the termination shock, heliosheath, and heliopause. New Horizons is observing the solar wind in the outer heliosphere and making the first direct observations of solar wind pickup ions. This paper reviews the observations of the solar wind plasma and magnetic fields throughout the heliosphere and in the interstellar medium.
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Affiliation(s)
- J D Richardson
- Kavli Institute for Astrophysics and Space Research and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA USA
| | - L F Burlaga
- NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 USA
| | - H Elliott
- Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 USA
| | - W S Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
| | - Y D Liu
- State Key Laboratory for Space Weather, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - R von Steiger
- Universität Bern, Bern, 2 Switzerland
- International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
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Richardson JD, Burlaga LF, Elliott H, Kurth WS, Liu YD, von Steiger R. Observations of the Outer Heliosphere, Heliosheath, and Interstellar Medium. SPACE SCIENCE REVIEWS 2022; 218:35. [PMID: 35664862 PMCID: PMC9156517 DOI: 10.1007/s11214-022-00899-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/14/2022] [Indexed: 05/08/2023]
Abstract
The Voyager spacecraft have left the heliosphere and entered the interstellar medium, making the first observations of the termination shock, heliosheath, and heliopause. New Horizons is observing the solar wind in the outer heliosphere and making the first direct observations of solar wind pickup ions. This paper reviews the observations of the solar wind plasma and magnetic fields throughout the heliosphere and in the interstellar medium.
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Affiliation(s)
- J. D. Richardson
- Kavli Institute for Astrophysics and Space Research and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA USA
| | - L. F. Burlaga
- NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 USA
| | - H. Elliott
- Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 USA
| | - W. S. Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
| | - Y. D. Liu
- State Key Laboratory for Space Weather, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - R. von Steiger
- Universität Bern, Bern, 2 Switzerland
- International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
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Galli A, Baliukin II, Bzowski M, Izmodenov VV, Kornbleuth M, Kucharek H, Möbius E, Opher M, Reisenfeld D, Schwadron NA, Swaczyna P. The Heliosphere and Local Interstellar Medium from Neutral Atom Observations at Energies Below 10 keV. SPACE SCIENCE REVIEWS 2022; 218:31. [PMID: 35673597 PMCID: PMC9165285 DOI: 10.1007/s11214-022-00901-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 05/05/2022] [Indexed: 05/08/2023]
Abstract
As the heliosphere moves through the surrounding interstellar medium, a fraction of the interstellar neutral helium, hydrogen, and heavier species crossing the heliopause make it to the inner heliosphere as neutral atoms with energies ranging from few eV to several hundred eV. In addition, energetic neutral hydrogen atoms originating from solar wind protons and from pick-up ions are created through charge-exchange with interstellar atoms. This review summarizes all observations of heliospheric energetic neutral atoms and interstellar neutrals at energies below 10 keV. Most of these data were acquired with the Interstellar Boundary Explorer launched in 2008. Among many other IBEX breakthroughs, it provided the first ever all-sky maps of energetic neutral atoms from the heliosphere and enabled the science community to measure in-situ interstellar neutral hydrogen, oxygen, and neon for the first time. These observations have revolutionized and keep challenging our understanding of the heliosphere shaped by the combined forces of the local interstellar flow, the local interstellar magnetic field, and the time-dependent solar wind.
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Affiliation(s)
- André Galli
- Physics Institute, University of Bern, Bern, Switzerland
| | - Igor I. Baliukin
- Space Research Institute of Russian Academy of Sciences, Moscow, Russia
- Moscow Center for Fundamental and Applied Mathematics, Lomonosov Moscow State University, Moscow, Russia
| | - Maciej Bzowski
- Space Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Vladislav V. Izmodenov
- Space Research Institute of Russian Academy of Sciences, Moscow, Russia
- Moscow Center for Fundamental and Applied Mathematics, Lomonosov Moscow State University, Moscow, Russia
| | | | | | | | | | | | | | - Paweł Swaczyna
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ USA
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Zirnstein EJ, Möbius E, Zhang M, Bower J, Elliott HA, McComas DJ, Pogorelov NV, Swaczyna P. In Situ Observations of Interstellar Pickup Ions from 1 au to the Outer Heliosphere. SPACE SCIENCE REVIEWS 2022; 218:28. [PMID: 35574273 PMCID: PMC9085710 DOI: 10.1007/s11214-022-00895-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/18/2022] [Indexed: 05/08/2023]
Abstract
Interstellar pickup ions are an ubiquitous and thermodynamically important component of the solar wind plasma in the heliosphere. These PUIs are born from the ionization of the interstellar neutral gas, consisting of hydrogen, helium, and trace amounts of heavier elements, in the solar wind as the heliosphere moves through the local interstellar medium. As cold interstellar neutral atoms become ionized, they form an energetic ring beam distribution comoving with the solar wind. Subsequent scattering in pitch angle by intrinsic and self-generated turbulence and their advection with the radially expanding solar wind leads to the formation of a filled-shell PUI distribution, whose density and pressure relative to the thermal solar wind ions grows with distance from the Sun. This paper reviews the history of in situ measurements of interstellar PUIs in the heliosphere. Starting with the first detection in the 1980s, interstellar PUIs were identified by their highly nonthermal distribution with a cutoff at twice the solar wind speed. Measurements of the PUI distribution shell cutoff and the He focusing cone, a downwind region of increased density formed by the solar gravity, have helped characterize the properties of the interstellar gas from near-Earth vantage points. The preferential heating of interstellar PUIs compared to the core solar wind has become evident in the existence of suprathermal PUI tails, the nonadiabatic cooling index of the PUI distribution, and PUIs' mediation of interplanetary shocks. Unlike the Voyager and Pioneer spacecraft, New Horizon's Solar Wind Around Pluto (SWAP) instrument is taking the only direct measurements of interstellar PUIs in the outer heliosphere, currently out to ∼ 47 au from the Sun or halfway to the heliospheric termination shock.
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Affiliation(s)
- E. J. Zirnstein
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 USA
| | - E. Möbius
- Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 USA
| | - M. Zhang
- Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 USA
| | - J. Bower
- Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 USA
| | - H. A. Elliott
- Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX 78228 USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249 USA
| | - D. J. McComas
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 USA
| | - N. V. Pogorelov
- Department of Space Science, The University of Alabama in Huntsville, Huntsville, AL 35805 USA
- Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - P. Swaczyna
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 USA
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Mostafavi P, Burlaga LF, Cairns IH, Fuselier SA, Fraternale F, Gurnett DA, Kim TK, Kurth WS, Pogorelov NV, Provornikova E, Richardson JD, Turner DL, Zank GP. Shocks in the Very Local Interstellar Medium. SPACE SCIENCE REVIEWS 2022; 218:27. [PMID: 35574274 PMCID: PMC9085707 DOI: 10.1007/s11214-022-00893-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 04/15/2022] [Indexed: 05/08/2023]
Abstract
Large-scale disturbances generated by the Sun's dynamics first propagate through the heliosphere, influence the heliosphere's outer boundaries, and then traverse and modify the very local interstellar medium (VLISM). The existence of shocks in the VLISM was initially suggested by Voyager observations of the 2-3 kHz radio emissions in the heliosphere. A couple of decades later, both Voyagers crossed the definitive edge of our heliosphere and became the first ever spacecraft to sample interstellar space. Since Voyager 1's entrance into the VLISM, it sampled electron plasma oscillation events that indirectly measure the medium's density, increasing as it moves further away from the heliopause. Some of the observed electron oscillation events in the VLISM were associated with the local heliospheric shock waves. The observed VLISM shocks were very different than heliospheric shocks. They were very weak and broad, and the usual dissipation via wave-particle interactions could not explain their structure. Estimates of the dissipation associated with the collisionality show that collisions can determine the VLISM shock structure. According to theory and models, the existence of a bow shock or wave in front of our heliosphere is still an open question as there are no direct observations yet. This paper reviews the outstanding observations recently made by the Voyager 1 and 2 spacecraft, and our current understanding of the properties of shocks/waves in the VLISM. We present some of the most exciting open questions related to the VLISM and shock waves that should be addressed in the future.
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Affiliation(s)
- P. Mostafavi
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - L. F. Burlaga
- NASA Goddard Space Flight Center, Code 673, Greenbelt, MD 20771 USA
| | - I. H. Cairns
- School of Physics, University of Sydney, Sydney, NSW 2006 Australia
| | - S. A. Fuselier
- Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228 USA
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249 USA
| | - F. Fraternale
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - D. A. Gurnett
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
| | - T. K. Kim
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - W. S. Kurth
- Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 USA
| | - N. V. Pogorelov
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
- Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35805 USA
| | - E. Provornikova
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - J. D. Richardson
- Kavli Institute for Astrophysics and Space Research, Cambridge, MA USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA USA
| | - D. L. Turner
- Johns Hopkins Applied Physics Laboratory, Laurel, MD 20723 USA
| | - G. P. Zank
- Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 USA
- Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35805 USA
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