DOCSLIB.ORG

Energetic Neutral Atom Imaging of the Heliospheric Boundary Region

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Energetic Neutral Atom Imaging of the Heliospheric Boundary Region JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. A8, PAGES 15,767-15,781, AUGUST 1, 2001 Energeticneutral atom imaging of the heliospheric boundary region Mike Gruntman,• Edmond C. Roelof,2 Donald G. Mitchell,2 Hans J. Fahr,3 HerbertO. Funsten,4 and David J. McComass Abstract.Energetic neutral atom (ENA) imagingis a powerfultechnique, which can remotely probethe properties of distanthot plasmas. Hot plasmas are abundant at theheliospheric boundary,the region where the expanding solar wind meets the surrounding local interstellar cloud.Here we presenta newconcept for imaging this boundary in ENA fluxes.Heliospheric ENAsare born from charge exchange between energetic protons and the background interstellaratomic hydrogen gas. The technique is idealfor studyingthe asymmetric three- dimensionalheliospheric interface region remotely, from 1 AU. We showthat ENA imagingin the0.2-6 keV energyrange will establishthe nature of thetelTnination shock and properties of hotproton populations in theheliosheath. We alsoexamine how the evolution of pickupproton populationsat andbeyond the shock can be explored.Global heliosphere ENA imageswill distinguishamong the competingmodels of the interactionbetween the Sunand the local interstellarmedium, and they will revealthe physics of importantprocesses in theinterface region.Heliospheric ENA fluxesare exceptionally weak, which makes imaging implementation difficult.Nonetheless, we showhow single-pixel ENA sensorscan image the heliosphere from a spicmingspacecraft on a typicalmission near 1 AU. Therequired instrumentation is briefly discussed. 1. Heliosphere equal the externalLISM pressureof the interstellarwind and magnetic field. The solar wind expansiontransitions to a The interactionof the expandingsolar wind plasmaand local subsonicflow at thetermination shock. There the kinetic energy interstellarmedium (LISM) createsthe heliosphere[Davis, of the supersonicflow is largelyconverted into thermalenergy 1955; Parker, 1963; Dessler, 1967; Axford, 1972]. The in the subsonicplasma beyond the shock. This subsonic heliosphereis a complexphenomenon where the solarwind and postshocksolar wind plasma flows around the termination interstellar plasmas, interstellar gas, magnetic fields, and shock and down the heliospherictail. The solar plasma energeticparticles all play importantroles. eventuallymixes with the interstellargalactic plasma in the tail The Sun's interactionwith the nearbyinterstellar medium is at distances of 1000-2000 AU. of considerableastrophysical interest. Our Sun is typicalof its Interstellarplasma does not penetrate through the heliopause, classof stars.Thus the hellosphereoffers a uniqueopportunity the discontinuoustransition boundary separating the solarand to study in detail the only accessible example of a galacticplasmas, but flows aroundthe hellopause.The region commonplaceand fundamentalastrophysical phenomenon, the betweenthe terminationshock and the hellopauseis calledthe formation of an astrosphere.Wood and Linsky [1998] heliosphericsheath (heliosheath). Other hellosphericmodels demonstratedthe possibility of remotely observing the make somewhatdifferent assumptions,including a subsonic astrospheresof nearby stars,which opensthe possibilitiesof interstellarwind, a weak terminationshock, an asymmetric comparativeastrosphere studies. solarwind, and may includean interstellarmagnetic field and A possible two-shock Sun-LISM interaction scenario cosmicrays [e.g., Fahr and Fichtner, 1991; Suess,1993; Linde [Baranov,1990; Baranovand Malama, 1993, 1995] illustrates et al., 1998; Zank, 1999]. In all the models,the hot shocked the main featuresof the hellosphere(Figure 1). The interstellar solar wind plasma fills the heliosheathand flows down the wind approachesthe hellosphere with a supersonicvelocity and hellospherictail. formsthe bow shock.The dynamicpressure of the expanding, Three major factors make the heliosphere essentially highly supersonicsolar wind decreaseswith the heliocenthc asymmetric.First, the partially ionized interstellargas of the distance.At a certaindistance from the Sunthis pressure would [.ISM moveswith a 26 km s-• speed(Figure 1) withrespect to the sun (interstellarwind). Second,the interstellarmagnetic field couldbe pointedin any direction.Third, the solarwind is anisotropic with the properties over the Sun's poles of lDepartmentSouthernCalifornia, ofAerospace Los Angeles, andMechanicalCalifornia. Engineering, Universitysignificantly differentfrom those closeto the ecliptic plane. 2AppliedPhysics Laboratory, Johns Hopkins University, Laurel, The hellospherehas been extensivelystudied both Maryland. theoreticallyand by variousexperimental techniques since the Universitiit3InstitutBonn, far AstrophysikBonn, Germany. und Extraterrestrische Forschung,early 1960s. Experimental dataon the region between the 4LosAlamos National Laboratory, Los Alamos, New Mexico. supersonicsolar wind and the surroundingLISM, the 5SouthwestResearch Institute, San Antonio, Texas. hellosphericinterface region, are scarce,mostly indirect, and often ambiguous.Although significantprogress was achieved Copyright2001 by theAmerican Geophysical Union in understandingthe Sun-LISM interaction,many important Papernumber 2000JA000328. questionsare still unanswered,for example:Is the solar wind 0148-0227/01/2000JA000328509.00 expansionterminated by a shock?What is the nature of the 15,767 15,768 GRUNTMAN ET AL.: ENERGETIC NEUTRAL ATOM IMAGING OF THE HELIOSPHERE BS Becausethe terminationshock and the interfaceregion beyond are so huge (hundreds of astronomicalunits), only remote techniquescan provide a global view of the time-varyingthree- dimensionalhellosphere on a continuousbasis. We argue that the technique for obtaining our first informationon the globalstructure of the heliosphereis already ISG at hand. This technique, energetic neutral atom (ENA) imaging, is sensitiveto the details of the structureof the s hellosphericinterface, to the nature of the terminationshock, M and to the evolutionof the pickup proton propertiesat and beyondthe terminationshock. The scientific promise of ENA imaging has been increasinglyargued for since the early 1980s and has led to extensivedevelopment of the conceptand instrumentation.The conceptwas validated by imaging the magnetosphericion Figure 1. Two-shockmodel of the interactionof the solarwind populationsusing ad hoc techniqueswith existingnon-ENA with the local interstellarmedium. Angle © is measuredfrom instruments[Roelof, 1987; Henderson et al., 1997] and the upwind direction. The hatched region between the dedicatedENA instruments[Orsini et al., 1992; Mitchell et al., terminationshock and the heliopausecontains the postshock 1993, 2000; Roelofet al., 1999;Brandt et al., 1999;Krimigis et solar wind plasma and pickup protons.The energeticneutral atoms (ENAs) producedin this region are the focus of this al., 2001; Pollock et al., 2000; Moore et al., 2000]. Williamset work. LISM, local interstellar medium; TS, termination shock; al. [1992] reviewed the conceptof magnetosphericimaging, HP, heliopause; BS, bow shock; CR, cosmicrays; ISP(G), and Gruntman [1997] reviewed ENA instrumentationand interstellarplasma (gas); B, magneticfield. presenteda historyof ENA experimentalstudy. Imaging of the hellospherein ENA fluxes has been advocatedfor sometime [Gruntmanet al., 1990; Gruntman, 1992, 1997; Hsieh and Gruntman,1993] as a way of exploringremotely properties of termination shock? What is the distance to the shock and its the hellosphericsheath plasma. The first dedicatedspace shape?Is the natureof the shockthe samein all directionsfrom experimentto detectthe heliosphericENAs wasprepared in the the upwind (with respect to the interstellarwind) to the mid-1980s[Gruntman et al., 1990] but has neverbeen flown. downwind?What happensto the solarwind pickupions at and ComplementaryEUV mapping of the hellopauseis being beyond the shock? We also know very little about the currently evaluated [Gruntman and Fahr, 1998, 2000; heliopauseand the bow shock. Gruntman,2001 a, 2001b]. Inferring the properties of the heliosphericinterface is In this articlewe presentthe conceptof heliosphereimaging complicatedby the complexity of the Sun-LISM interaction. using naturally occurring ENA fluxes. ENA imaging will The plasmaand neutral gas flows aremultifluid with oftennon- distinguish among the competing Sun-LISM interaction Maxwellian ion velocity distributions.Plasmas and neutral models,radically constrain the models,and explorethe physics atompopulations are not in thermodynamicequilibrium, many of the criticaland often superimposedprocesses in the interface processesare nonstationary,energetic ions substantiallymodify region.Heliospheric ENA fluxesare exceptionallyweak, which the shocks,and galacticand anomalouscosmic rays contribute makes imaging implementationnontrivial. Thereforewe also importantpressure gradients. The mean free path of neutral describehow the hellospherecan be imagedon a realisticspace atoms is comparableto the size of the heliosphere,which missionbased on the availableinstrumentation technology. strongly limits applicability of gasdynamical methods. Consequently,a self-consistentmodel of the stationary 2. Heliospheric Interface heliospherehas yet to be developed. The lack of the direct experimentaldata severelylimits our The propertiesof the LISM determineimportant features of abilityto understandthe detailsof the hellosphericinteractions. the Sun-LISM interaction.The physicsof the LISM is far from Furtherprogress in studyingthe Sun-LISM interactioncritically
Load more

Recommended publications
  • ASPERA-3: Analyser of Space Plasmas and Energetic Neutral Atoms
    ASPERA-3: Analyser of Space Plasmas and Energetic Neutral Atoms R. Lundin1, S. Barabash1 and the ASPERA-3 team: M. Holmström1, H. Andersson1, M. Yamauchi1, H. Nilsson1, A. Grigorev, D. Winningham2, R. Frahm2, J.R. Sharber2, J.-A. Sauvaud3, A. Fedorov3, E. Budnik3, J.-J. Thocaven3, K. Asamura4, H. Hayakawa4, A.J. Coates5, Y. Soobiah5 D.R. Linder5, D.O. Kataria5, C. Curtis6, K.C. Hsieh6, B.R. Sandel6, M. Grande7, M. Carter7, D.H. Reading7, H. Koskinen8, E. Kallio8, P. Riihela8, T. Säles8, J. Kozyra9, N. Krupp10, J. Woch10, M. Fraenz10, J. Luhmann11 , D. Brain11, S. McKenna-Lawler12, R. Cerulli-Irelli13, S. Orsini13, M. Maggi13, A. Milillo13, E. Roelof14, S. Livi14, P. Brandt14, P. Wurz15, P. Bochsler15 & A. Galli15 1 Swedish Institute of Space Physics, Box 812, S-98 128 Kiruna, Sweden 2 Southwest Research Institute, San Antonio, TX 7228-0510, USA 3 Centre d’Etude Spatiale des Rayonnements, BP-4346, F-31028 Toulouse, France 4 Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamichara, Japan 5 Mullard Space Science Laboratory, University College London, Surrey RH5 6NT, UK 6 University of Arizona, Tucson, AZ 85721, USA 7 Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK 8 Finnish Meteorological Institute, Box 503, FIN-00101 Helsinki, Finland; and Department of Physical Sciences, PO Box 64, University of Helsinki, FIN-00014 Helsinki, Finland 9 Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143, USA 10 Max-Planck-Institut für Sonnensystemforschung, D-37191 Katlenburg-Lindau, Germany 11 Space Science Laboratory, University of California at Berkeley, Berkeley, CA 94720-7450, USA 12 Space Technology Ltd, National University of Ireland, Maynooth, Co.
    [Show full text]
  • The Ionosphere of Mars and Its Importance for Climate Evolution a Community White Paper Submitted to the 2011 Planetary Science Decadal Survey
    The ionosphere of Mars and its importance for climate evolution A community white paper submitted to the 2011 Planetary Science Decadal Survey Primary authors: Paul Withers (Boston University, USA, 617 353 1531, [email protected]) Jared Espley (NASA Goddard Space Flight Center, USA) Rob Lillis (University of California Berkeley, USA) Dave Morgan (University of Iowa, USA) Co-authors: Laila Andersson (University of Colorado, Francois Leblanc (Institut Pierre-Simon USA) Laplace, France) Mathieu Barthélemy (University of Grenoble, Mark Lester (University of Leicester, UK) France) Michael Liemohn (University of Michigan, Stephen Bougher (University of Michigan, USA) USA) Jean Lilensten (University of Grenoble, David Brain (University of California France) Berkeley, USA) Janet Luhmann (University of California Stephen Brecht (Bay Area Research Berkeley, USA) Corporation, USA) Rickard Lundin (Institute of Space Physics Tom Cravens (University of Kansas, USA) (IRF), Sweden) Geoff Crowley (Atmospheric and Space Anthony Mannucci (Jet Propulsion Technology Research Associates, USA) Laboratory, USA) Justin Deighan (University of Virginia, USA) Susan McKenna-Lawlor (National University Scott England (University of California of Ireland, Ireland) Berkeley, USA) Michael Mendillo (Boston University, USA) Jeffrey Forbes (University of Colorado, USA) Erling Nielsen (Max Planck Institute for Solar Matt Fillingim (University of California System Research, Germany) Berkeley, USA) Martin Pätzold (University of Cologne, Jane Fox (Wright State University, USA)
    [Show full text]
  • Tailward Flow of Energetic Neutral Atoms Observed at Venus A
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, E00B15, doi:10.1029/2008JE003096, 2008 Click Here for Full Article Tailward flow of energetic neutral atoms observed at Venus A. Galli,1 M.-C. Fok,2 P. Wurz,1 S. Barabash,3 A. Grigoriev,3 Y. Futaana,3 M. Holmstro¨m,3 A. Ekenba¨ck,3 E. Kallio,4 and H. Gunell5 Received 31 January 2008; revised 11 April 2008; accepted 26 August 2008; published 2 December 2008. [1] The Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) experiment on Venus Express provides the first measurements of energetic neutral atoms (ENAs) from Venus. The results improve our knowledge on the interaction of the solar wind with a nonmagnetized planet and they present an observational constraint to existing plasma models. We characterize the tailward flow of hydrogen ENAs observed on the nightside by providing global images of the ENA intensity. The images show a highly concentrated tailward flow of hydrogen ENAs tangential to the Venus limb around the Sun’s direction. No oxygen ENAs above the instrument threshold are detected. The observed ENA intensities are reproduced with a simple ENA model within a factor of 2, indicating that the observed hydrogen ENAs originate from shocked solar wind protons that charge exchange with the neutral hydrogen exosphere. Citation: Galli, A., M.-C. Fok, P. Wurz, S. Barabash, A. Grigoriev, Y. Futaana, M. Holmstro¨m, A. Ekenba¨ck, E. Kallio, and H. Gunell (2008), Tailward flow of energetic neutral atoms observed at Venus, J. Geophys. Res., 113, E00B15, doi:10.1029/2008JE003096. 1. Introduction boundary where the planetary ions start to dominate the plasma or as the boundary where the interplanetary mag- [2] As a part of the Venus Express (VEX) scientific netic field BIMF piles up around the ionosphere.
    [Show full text]
  • Science Objectives May Be Summarized As Follows
    MAGNETOSPHERE IMAGING INSTRUMENT (MIMI) 9 ON THE CASSINI MISSION TO SATURN/TITAN 2. Scientific Objectives MIMI science objectives may be summarized as follows: Saturn • Determine the global configuration and dynamics of hot plasma in the magneto- sphere of Saturn through energetic neutral particle imaging of ring current, radia- tion belts, and neutral clouds. • Study the sources of plasmas and energetic ions through in situ measurements of energetic ion composition, spectra, charge state, and angular distributions. • Search for, monitor, and analyze magnetospheric substorm-like activity at Saturn. • Determine through the imaging and composition studies the magnetosphere– satellite interactions at Saturn and understand the formation of clouds of neutral hydrogen, nitrogen, and water products. •Investigate the modification of satellite surfaces and atmospheres through plasma and radiation bombardment. • Study Titan’s cometary interaction with Saturn’s magnetosphere (and the solar wind) via high-resolution imaging and in situ ion and electron measurements. • Measure the high energy (Ee > 1 MeV, Ep > 15 MeV) particle component in the inner (L < 5 RS) magnetosphere to assess cosmic ray albedo neutron decay (CRAND) source characteristics. •Investigate the absorption of energetic ions and electrons by the satellites and rings in order to determine particle losses and diffusion processes within the mag- netosphere. • Study magnetosphere–ionosphere coupling through remote sensing of aurora and in situ measurements of precipitating energetic ions and electrons. Jupiter • Study ring current(s), plasma sheet, and neutral clouds in the magnetosphere and magnetotail of Jupiter during Cassini flyby, using global imaging and in situ mea- surements. S. M. KRIMIGIS ET AL. 10 Interplanetary • Determine elemental and isotopic composition of local interstellar medium through measurements of interstellar pickup ions.
    [Show full text]
  • Neutral Atom Imaging of Solar Wind Interaction with the Earth and Venus M.-C
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, A01206, doi:10.1029/2003JA010094, 2004 Neutral atom imaging of solar wind interaction with the Earth and Venus M.-C. Fok, T. E. Moore, and M. R. Collier NASA Goddard Space Flight Center, Greenbelt, Maryland, USA T. Tanaka Department of Earth and Planetary Science, Kyushu University, Fukuoka, Japan Received 18 June 2003; revised 24 September 2003; accepted 9 October 2003; published 13 January 2004. [1] Observations from the Low-Energy Neutral Atom (LENA) imager on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission have emerged as a promising new tool for studying the solar wind interaction with the terrestrial magnetosphere. Strong LENA emissions are seen from the magnetosheath during magnetic storms, especially during high solar wind dynamic pressure when the magnetopause is strongly compressed and the magnetosheath penetrates deeply into the exosphere. Venus, unlike the Earth, has no intrinsic magnetic field, so the solar wind penetrates deeply and interacts directly with its upper atmosphere. Energy transfer processes enhance atomic escape and thus play a potentially important role in the evolution of the atmosphere. We have performed simulations of the solar wind interaction with both Earth and Venus and compared the results to LENA observations at the Earth. Low-energy neutral atom emissions from Venus are calculated based on the global MHD model of Tanaka. We found the simulated energetic neutral atom (ENA) emissions from Venus magnetosheath are comparable or greater than for the Earth. The Venus ionopause is clearly seen in the modeled oxygen ENA images. This simulation work demonstrates the feasibility of remotely sensing the Venusian solar wind interaction and resultant atmospheric escape using fast neutral atom imaging.
    [Show full text]
  • The Heliotail N
    The Astrophysical Journal Letters, 812:L6 (7pp), 2015 October 10 doi:10.1088/2041-8205/812/1/L6 © 2015. The American Astronomical Society. All rights reserved. THE HELIOTAIL N. V. Pogorelov1,2, S. N. Borovikov2, J. Heerikhuisen1,2, and M. Zhang3 1 Department of Space Sciences, The University of Alabama in Huntsville, AL 35805, USA; [email protected] 2 Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, AL 35805, USA 3 Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901, USA Received 2015 July 26; accepted 2015 September 18; published 2015 October 6 ABSTRACT The heliotail is formed when the solar wind (SW) interacts with the local interstellar medium (LISM) and is shaped by the interstellar magnetic field (ISMF). While there are no spacecraft available to perform in situ measurements of the SW plasma and heliospheric magnetic field (HMF) in the heliotail, it is of importance for the interpretation of measurements of energetic neutral atom fluxes performed by Interstellar Boundary Explorer. It has been shown recently that the orientation of the heliotail in space and distortions of the unperturbed LISM caused by its presence may explain the anisotropy in the TeV cosmic ray flux detected in air shower observations. The SW flow in the heliotail is a mystery itself because it is strongly affected by charge exchange between the SW ions and interstellar neutral atoms. If the angle between the Sun’s magnetic and rotation axes is constant, the SW in the tail tends to be concentrated inside the HMF spirals deflected tailward.
    [Show full text]
  • Simulation of Energetic Neutral Atoms at Mars and a Comparison with ASPERA-3 Data
    Simulation of Energetic Neutral atoms at Mars and a Comparison with ASPERA-3 data H. Gunell,∗ K. Brinkfeldt, S. Barabash, M. Holmstr¨om,† A. Ekenb¨ack, Y. Futaana, R. Lundin, H. Andersson, M. Yamauchi, and A. Grigoriev Swedish Institute of Space Physics, Kiruna, Sweden E. Kallio, T. S¨ales, P. Riihela, and W. Schmidt Finnish Meteorological Institute, Box 503 FIN-00101 Helsinki, Finland P. Brandt, E. Roelof, D. Williams, and S. Livi Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723-6099, USA J. D. Winningham, R. A. Frahm, J. R. Sharber, and J. Scherrer Southwest Research Institute, San Antonio, TX 7228-0510, USA A. J. Coates, D. R. Linder, and D. O. Kataria Mullard Space Science Laboratory, University College London, Surrey RH5 6NT, UK Hannu E. J. Koskinen University of Helsinki, Department of Physical Sciences P.O. Box 64, 00014 Helsinki J. Kozyra Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143, USA J. Luhmann Space Science Laboratory, University of California at Berkeley, Berkeley, CA 94720-7450, USA C. C. Curtis, K. C. Hsieh, and B. R. Sandel University of Arizona, Tucson, AZ 85721, USA M. Grande and M. Carter Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK J.-A. Sauvaud, A. Fedorov, and J.-J. Thocaven Centre d’Etude Spatiale des Rayonnements, BP-4346, F-31028 Toulouse, France S. McKenna-Lawlor Space Technology Ireland., National University of Ireland, Maynooth, Co. Kildare, Ireland S. Orsini, R. Cerulli-Irelli, and M. Maggi Instituto di Fisica dello Spazio Interplanetari, I-00133 Rome, Italy P. Wurz and P.
    [Show full text]
  • The Science Return from Venus Express the Science Return From
    The Science Return from Venus Express Venus Express Science Håkan Svedhem & Olivier Witasse Research and Scientific Support Department, ESA Directorate of Scientific Programmes, ESTEC, Noordwijk, The Netherlands Dmitri V. Titov Max Planck Institute for Solar System Studies, Katlenburg-Lindau, Germany (on leave from IKI, Moscow) ince the beginning of the space era, Venus has been an attractive target for Splanetary scientists. Our nearest planetary neighbour and, in size at least, the Earth’s twin sister, Venus was expected to be very similar to our planet. However, the first phase of Venus spacecraft exploration (1962-1985) discovered an entirely different, exotic world hidden behind a curtain of dense cloud. The earlier exploration of Venus included a set of Soviet orbiters and descent probes, the Veneras 4 to14, the US Pioneer Venus mission, the Soviet Vega balloons and the Venera 15, 16 and Magellan radar-mapping orbiters, the Galileo and Cassini flybys, and a variety of ground-based observations. But despite all of this exploration by more than 20 spacecraft, the so-called ‘morning star’ remains a mysterious world! Introduction All of these earlier studies of Venus have given us a basic knowledge of the conditions prevailing on the planet, but have generated many more questions than they have answered concerning its atmospheric composition, chemistry, structure, dynamics, surface-atmosphere interactions, atmospheric and geological evolution, and plasma environment. It is now high time that we proceed from the discovery phase to a thorough
    [Show full text]
  • Neutral Atom Imaging of the Solar Wind‐Magnetosphere‐Exosphere
    RESEARCH LETTER Neutral Atom Imaging of the Solar Wind‐Magnetosphere‐ 10.1029/2020GL089362 Exosphere Interaction Near the Subsolar Magnetopause Key Points: S. A. Fuselier1,2 , M. A. Dayeh1,2 , A. Galli3 , H. O. Funsten4 , N. A. Schwadron5 , • ENA cameras image both 6 7 8 1 9,10 magnetosheath and magnetospheric S. M. Petrinec , K. J. Trattner , D. J. McComas , J. L. Burch , S. Toledo‐Redondo , plasmas in the vicinity of the J. R. Szalay8 , and R. J. Strangeway11 subsolar magnetopause • Magnetospheric plasma is not 1Southwest Research Institute, San Antonio, TX, USA, 2Department of Physics and Astronomy, University of Texas at San distributed evenly across the dayside Antonio, San Antonio, TX, USA, 3Physics Institute, University of Bern, Bern, Switzerland, 4Los Alamos National near the magnetopause 5 6 • The exospheric hydrogen density Laboratory, Los Alamos, NM, USA, Space Science Center, University of New Hampshire, Durham, NH, USA, Lockheed 7 near the magnetopause may have a Martin Advanced Technology Center, Palo Alto, CA, USA, Laboratory for Atmospheric and Space Physics, University of weak dependence on solar F10.7 Colorado Boulder, Boulder, CO, USA, 8Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA, 9Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse, Toulouse, France, 10Department of Supporting Information: Electromagnetism and Electronics, University of Murcia, Murcia, Spain, 11Earth and Space Sciences, University of • Supporting Information S1 California, Los Angeles, CA, USA Correspondence to: Abstract Energetic neutral atoms (ENAs) created by charge‐exchange of ions with the Earth's hydrogen S. A. Fuselier, exosphere near the subsolar magnetopause yield information on the distribution of plasma in the outer [email protected] magnetosphere and magnetosheath.
    [Show full text]
  • Moderate Geomagnetic Storm (2122 January 2005) Triggered by an Outstanding Coronal Mass Ejection Viewed Via Energetic Neutral At
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, A08213, doi:10.1029/2009JA014663, 2010 Moderate geomagnetic storm (21–22 January 2005) triggered by an outstanding coronal mass ejection viewed via energetic neutral atoms Susan McKenna‐Lawlor,1 Lu Li,2 Iannis Dandouras,3 Pontus C. Brandt,4 Yihua Zheng,4 Stas Barabash,5 Radoslav Bucik,6 Karel Kudela,7 Jan Balaz,1,7 and Igor Strharsky1,7 Received 21 July 2009; revised 19 October 2009; accepted 5 November 2009; published 14 August 2010. [1] An outstanding flare on 20 January 2005 was accompanied by a coronal mass ejection which arrived at the magnetopause at ∼1712 UT, 21 January, and produced a strong compression‐pressure pulse. Enhanced magnetospheric activity was stimulated. The associated development between <1800 UT and >02.19 UT on 21–22 January, 2005 of a ring current disturbance in energetic neutral atom (ENA) data, recorded aboard both the Double Star and the IMAGE (Imager for Magnetopause‐to‐Aurora Global Exploration) spacecraft, is described. A magnetic storm from ∼1712 UT, 21 January, reached minimum Dst = ∼−101 nT at ∼0600 UT, 22 January, and its recovery phase endured until 27 January. ENA data indicate that the ring current experienced a deep injection of H+ and O+ ions at ∼1830 UT when IMF Bz was oriented southward. At this time, the ring current was strongly asymmetric, although later it became more symmetric. Bz turned northward at 1946 UT. From ∼0224 to ∼0612 UT on 22 January, Bz fluctuated such that it intermittently pointed southward (±10 nT). The moderate but extended response of the geomagnetosphere to the strong pressure pulse is explained by a slow evolution in the orientation of Bz under conditions of enhanced plasma sheet density.
    [Show full text]
  • Juno Energetic Neutral Atom (ENA) Remote Measurements of Magnetospheric Injection-Dynamics in Jupiter’S Io Torus Regions
    Juno Energetic Neutral Atom (ENA) Remote Measurements of Magnetospheric Injection-Dynamics in Jupiter’s Io Torus Regions B. H. Mauk1, G. Clark 1, F. Allegrini2,3, F. Bagenal4, S. J. Bolton2, J. E. P. Connerney5,6, D. K. Haggerty1, P. Kollmann1, D. G. Mitchell1, C. P. Paranicas 1, A. M. Rymer1 1The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA ([email protected]) 2Southwest Research Institute, San Antonio, Texas, USA 3Physics and Astronomy Department, University of Texas at San Antonio, Texas, USA 4University of Colorado, Laboratory for Space and Atmospheric Sciences, Boulder, Colorado, USA 5NASA Goddard Space Flight Center, Greenbelt, Maryland, USA 6Space Research Corporation, Annapolis, Maryland, USA Corresponding author: Barry H. Mauk ([email protected]) Key Points: • The first Jovian off-equator Energetic Neutral Atom (ENA) viewings reveal distinct emissions from Jupiter and the orbits of Io and Europa. • Strong ENA emissions from Io’s orbit are associated with energetic particle injections near Io’s orbit observed several hours earlier. • Energetic particle injections occur inside Io’s orbit, a surprise given expectations that outward transport from Io drives injections. 1 Abstract In planetary magnetospheres, singly charged energetic particles, trapped by the planet’s magnetic field, can steal electrons from cold gas atoms and become neutralized. These now Energetic Neutral Atoms (ENAs), no longer confined by the magnetic field, can travel out of the system similar to photons leaving a hot oven. ENA’s have been used to image magnetospheric processes at Earth, Jupiter, and Saturn. At Jupiter, the opportunities to image the magnetosphere have been limited and always from the perspective of the near-equatorial plane at distance >139 RJ.
    [Show full text]
  • The Mercury Environment: a Literature Survey
    TRITA-ALP-2003-02 Report ISSN 1103-6613 ISRN KTH/ALP/R—03 /2 -- SE The Mercury Environment: A Literature Survey J. A. Cumnock1,2 and L. G. Blomberg1 1Alfvén Laboratory, Royal Institute of Technology, Stockholm 2Center for Space Sciences, University of Texas at Dallas Stockholm, April 2003 TRITA-ALP-2003-02 Contents Introduction .................................................................................................................... 3 The Solar Wind at Mercury’s Orbit.................................................................................. 5 Mercury’s Magnetosphere............................................................................................... 5 Mercury’s Atmosphere ..................................................................................................14 Mercury’s Surface Properties ........................................................................................16 Mercury’s Planetary Magnetic Field..............................................................................16 Miscellaneous Mercury Publications ..............................................................................17 Compilations on Mercury Science..................................................................................20 2 Abstract A literature survey was conducted focusing primarily on the plasma environment of planet Mercury, and secondarily on its neutral atmosphere and the electrical properties of the planetary surface. An extensive literature list, with narrative comments for selected publications
    [Show full text]