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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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Zirnstein EJ, Giacalone J, Kumar R, McComas DJ, Dayeh MA, Heerikhuisen J. Turbulence in the Local Interstellar Medium and the IBEX Ribbon. THE ASTROPHYSICAL JOURNAL 2020; 888:10.3847/1538-4357/ab594d. [PMID: 32020922 PMCID: PMC6999793 DOI: 10.3847/1538-4357/ab594d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The effects of turbulence in the very local interstellar medium (VLISM) have been proposed by Giacalone & Jokipii (2015) to be important in determining the structure of the Interstellar Boundary Explorer (IBEX) ribbon via particle trapping by magnetic mirroring. We further explore this effect by simulating the motion of charged particles in a turbulent magnetic field superposed on a large-scale mean field, which we consider to be either spatially-uniform or a draped field derived from a 3D MHD simulation. We find that the ribbon is not double-peaked, in contrast to Giacalone & Jokipii (2015). However, the magnetic mirror force still plays an important role in trapping particles. Furthermore, the ribbon's thickness is considerably larger if the large-scale mean field is draped around the heliosphere. Voyager 1 observations in the VLISM show a turbulent field component that is stronger than previously thought, which we test in our simulation. We find that the inclusion of turbulent fluctuations at scales ≳100 au and power consistent with Voyager 1 observations produces a ribbon whose large-scale structure is inconsistent with IBEX observations. However, restricting fluctuations to <100 au produces a smoother ribbon structure similar to IBEX observations. Different turbulence realizations produce different small-scale features (≲10°) in the ribbon, but its large-scale structure is robust if the maximum fluctuation size is ≲50 au. This suggests that the magnetic field structure at scales ≲50 au is determined by the heliosphere-VLISM interaction and cannot entirely be represented by pristine interstellar turbulence.
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Affiliation(s)
- E J Zirnstein
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
| | - J Giacalone
- Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - R Kumar
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
| | - D J McComas
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
| | - M A Dayeh
- Southwest Research Institute, San Antonio, TX 78228, USA
| | - J Heerikhuisen
- Department of Mathematics and Statistics, University of Waikato, Hamilton, New Zealand
- Department of Space Science, University of Alabama in Huntsville, Huntsville, AL 35899, USA
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Hadid LZ, Sahraoui F, Galtier S, Huang SY. Compressible Magnetohydrodynamic Turbulence in the Earth's Magnetosheath: Estimation of the Energy Cascade Rate Using in situ Spacecraft Data. PHYSICAL REVIEW LETTERS 2018; 120:055102. [PMID: 29481187 DOI: 10.1103/physrevlett.120.055102] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 10/18/2017] [Indexed: 06/08/2023]
Abstract
The first estimation of the energy cascade rate |ε_{C}| of magnetosheath turbulence is obtained using the Cluster and THEMIS spacecraft data and an exact law of compressible isothermal magnetohydrodynamics turbulence. The mean value of |ε_{C}| is found to be close to 10^{-13} J m^{-3} s^{-1}, at least 2 orders of magnitude larger than its value in the solar wind (∼10^{-16} J m^{-3} s^{-1} in the fast wind). Two types of turbulence are evidenced and shown to be dominated either by incompressible Alfvénic or compressible magnetosoniclike fluctuations. Density fluctuations are shown to amplify the cascade rate and its spatial anisotropy in comparison with incompressible Alfvénic turbulence. Furthermore, for compressible magnetosonic fluctuations, large cascade rates are found to lie mostly near the linear kinetic instability of the mirror mode. New empirical power-laws relating |ε_{C}| to the turbulent Mach number and to the internal energy are evidenced. These new findings have potential applications in distant astrophysical plasmas that are not accessible to in situ measurements.
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Affiliation(s)
- L Z Hadid
- Swedish Institute of Space Physics, SE 751 21, Uppsala, Sweden and LPP, CNRS, Ecole Polytechnique, Université Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Université, PSL Research University, 91128 Palaiseau, France
| | - F Sahraoui
- LPP, CNRS, Ecole Polytechnique, Université Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Université, PSL Research University, 91128 Palaiseau, France
| | - S Galtier
- LPP, CNRS, Ecole Polytechnique, Université Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Université, PSL Research University, 91128 Palaiseau, France
| | - S Y Huang
- School of Electronic Information, Wuhan University, Wuhan 430072, China
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Andrés N, Galtier S, Sahraoui F. Exact law for homogeneous compressible Hall magnetohydrodynamics turbulence. Phys Rev E 2018; 97:013204. [PMID: 29448457 DOI: 10.1103/physreve.97.013204] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Indexed: 06/08/2023]
Abstract
We derive an exact law for three-dimensional (3D) homogeneous compressible isothermal Hall magnetohydrodynamic turbulence, without the assumption of isotropy. The Hall current is shown to introduce new flux and source terms that act at the small scales (comparable or smaller than the ion skin depth) to significantly impact the turbulence dynamics. The law provides an accurate means to estimate the energy cascade rate over a broad range of scales covering the magnetohydrodynamic inertial range and the sub-ion dispersive range in 3D numerical simulations and in in situ spacecraft observations of compressible turbulence. This work is particularly relevant to astrophysical flows in which small-scale density fluctuations cannot be ignored such as the solar wind, planetary magnetospheres, and the interstellar medium.
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Affiliation(s)
- N Andrés
- LPP, CNRS, Ecole Polytechnique, UPMC Univ. Paris 06, Univ. Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Universités, PSL Research University, F-91128 Palaiseau, France
| | - S Galtier
- LPP, CNRS, Ecole Polytechnique, UPMC Univ. Paris 06, Univ. Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Universités, PSL Research University, F-91128 Palaiseau, France
- Département de Physique, Université Paris-Sud, Orsay, France
| | - F Sahraoui
- LPP, CNRS, Ecole Polytechnique, UPMC Univ. Paris 06, Univ. Paris-Sud, Observatoire de Paris, Université Paris-Saclay, Sorbonne Universités, PSL Research University, F-91128 Palaiseau, France
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