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  • 1
    Electronic Resource
    Electronic Resource
    Density and magnetic field fluctuations observed by ISEE 1–2 in the quiet magnetosheath (1995)
    Springer
    Annales geophysicae 13 (1995), S. 343-357 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We analyse the fluctuations of the electron density and of the magnetic field in the Earth’s magnetosheath to identify the waves observed below the proton gyrofrequency. We consider two quiet magnetosheath crossings i.e. 2 days characterized by small-amplitude waves, for which the solar wind dynamic pressure was low. On 2 August 1978 the spacecraft were in the outer magnetosheath. We compare the properties of the observed narrow-band waves with those of the unstable linear wave modes calculated for an homogeneous plasma with Maxwellian electron and bi-Maxwellian (anisotropic) proton and alpha particle distributions. The Alfvén ion cyclotron (AIC) mode appears to be dominant in the data, but there are also density fluctuations nearly in phase with the magnetic fluctuations parallel to the magnetic field. Such a phase relation can be explained neither by the presence of a proton or helium AIC mode nor by the presence of a fast mode in a bi-Maxwellian plasma. We invoke the presence of the helium cut-off mode which is marginally stable in a bi-Maxwellian plasma with 〈alpha〉 particles: the observed phase relation could be due to a hybrid mode (proton AIC + helium cut-off) generated by a non-Maxwellian or a non-gyrotropic part of the ion distribution functions in the upstream magnetosheath. On 2 September 1981 the properties of the fluctuations observed in the middle of the magnetosheath can be explained by pure AIC waves generated by protons which have reached a bi-Maxwellian equilibrium. For a given wave mode, the phase difference between B\Vert and the density is sensitive to the shape of the ion and electron distribution functions: it can be a diagnosis tool for natural and simulated plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-995-0343-1
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  • 2
    Electronic Resource
    Electronic Resource
    COROTATING AND TRANSIENT SOLAR WIND FLOWS IN THREE DIMENSIONS (1996)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 34 (1996), S. 35-73 
    Details
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Notes: Abstract Two types of flows dominate the large-scale structure of the solar wind: corotating flows and transient disturbances. Corotating flows are associated with spatial variability in the coronal expansion and solar rotation, whereas transient disturbances are associated with episodic ejections of material into interplanetary space from coronal regions not previously participating in the solar wind expansion. Ulysses' recent epic journey over the poles of the Sun has provided new insights on the three-dimensional nature of both corotating flows and transient disturbances in the solar wind and their evolution with heliocentric distance and latitude. This paper provides a simple physical description of the origins and dynamics of both of these types of solar wind flows, highlighting new understanding gained from the unique Ulysses high-latitude observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.astro.34.1.35
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  • 3
    Electronic Resource
    Electronic Resource
    A magnetic reconnection X-line extending more than 390 Earth radii in the solar wind (2006)
    [s.l.] : Nature Publishing Group
    Nature 439 (2006), S. 175-178 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Magnetic reconnection in a current sheet converts magnetic energy into particle energy, a process that is important in many laboratory, space and astrophysical contexts. It is not known at present whether reconnection is fundamentally a process that can occur over an extended region in space or ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature04393
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  • 4
    Electronic Resource
    Electronic Resource
    Coronal mass ejections: The link between solar and geomagnetic activityf| (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 2638-2645 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Coronal mass ejections are spectacular manifestations of solar activity in which 10+15–10+16 g of solar material are propelled outward into interplanetary space. Recent work has demonstrated that these events are the prime link between solar activity and large, nonrecurrent geomagnetic storms, closing a loop in a body of research extending back more than 130 years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.860701
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  • 5
    Electronic Resource
    Electronic Resource
    Magnetospheric plasma analyzer for spacecraft with constrained resources (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1026-1033 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A light-weight, low-power, plasma analyzer is described that can be used for measuring the plasma environments of spacecraft with constrained resources. A unique system using a single electrostatic analyzer coupled to a single array of channel electron multipliers allows measurement of the three-dimensional energy per charge distributions of both ions and electrons over E/q ranges from ∼1 eV/q to (approximately-greater-than)40 keV/q. Particles selected by the analyzer are post-accelerated into the multipliers to maintain sensitivity for the lowest energy particles. An instrument using this concept called the magnetospheric plasma analyzer (MPA) is described. Presently, three MPAs are in geosynchronous orbits (GEO) aboard spacecraft with International Designators of 1989-046, 1990-095, and 1991-080. The MPA and its response characteristics are described, and examples of on-orbit data showing some of the MPA capabilities are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144173
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  • 6
    Electronic Resource
    Electronic Resource
    The sources of material comprising a mass ejection coronal transient (1975)
    Springer
    Solar physics 45 (1975), S. 363-376 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The origin of the material which is ejected during a white light coronal transient has not been determined heretofore. Study of a disturbance on 26 and 27 August 1973, during which a slowly ascending prominence and a more rapid accompanying coronal transient were simultaneously observed, helps to resolve this question. Prominence images obtained in Hα 6563 Å and in He II 304 Å are nearly identical. The mass ejection transient observed in white light (3700–7000 Å) appeared to be a loop about 1 R⊙ higher than the top of the ascending prominence; it accelerated away from the prominence below it. These observations imply: (1) the bulk of the ejected material did not originate in the ascending prominence; (2) therefore, most of the material must have come from the low corona above the prominence, (and was at coronal temperatures during its outward passage); and (3) the total event - ascending prominence accompanied by coronal mass ejection - was far larger, more energetic, and longer lasting than would be inferred from the prominence observations alone. The transient of 26–27 August was slow and of atypical shape compared to other mass ejection transients, but we believe that these three conclusions apply to most, if not all, of the more than 60 loop-shaped coronal transients observed by the High Altitude Observatory's coronagraph during the nine-month flight of Skylab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00158456
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  • 7
    Electronic Resource
    Electronic Resource
    White light and radio studies of the coronal transient of 14–15 September 1973 (1976)
    Springer
    Solar physics 49 (1976), S. 369-394 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of a coronal transient event were obtained in white light by the Skylab coronagraph and at metric wavelengths by the radioheliograph and spectrograph at Culgoora and the spectrograph-interferometer at Boulder. The continuum radio burst was found to originate above the outward-moving white light loop - a region of compressed material headed by a bow wave. The computed density in the region of radio emission, based on either gyro-synchrotron or harmonic plasma radiation mechanisms, was approximately 10 times the ambient coronal density; this is compatible with the density deduced from the white light observations. The magnetic energy density derived from the radio observations was greater than 10 times the thermal energy density, marginally larger than the kinetic energy density in the fastest moving portion of the transient, and considerably larger in most other regions. The ambient medium, the white light front, the compression region, the loop, and the slower, massive flow of material behind are each examined. It is found that the plasma was magnetically controlled throughout, and that magnetic forces provided the principal mechanism for acceleration of the transient material from the Sun.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162459
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  • 8
    Electronic Resource
    Electronic Resource
    Plasma acceleration at the Earth's magnetopause: evidence for reconnection (1979)
    [s.l.] : Nature Publishing Group
    Nature 282 (1979), S. 243-246 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A characteristic of magnetic field reconnection is the acceleration of plasma as it flows across a rotational discontinuity. At the Earth's magnetopause this effect has only been observed recently during a few magnetopause crossings by the ISEE satellites. For one example analysed in detail ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/282243a0
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  • 9
    Electronic Resource
    Electronic Resource
    Ulysses solar wind observations to 56° south (1995)
    Springer
    Space science reviews 72 (1995), S. 93-98 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the 25 months since Jupiter flyby, the Ulysses spacecraft has climbed southward to a heliolatitude of 56°. This transit has been marked by an evolution from slow, dense coronal streamer belt solar wind through two regions where the rotation of the Sun carried Ulysses back and forth between streamer belt and polar coronal hole flows, and finally into a region of essentially continuous fast, low density solar wind from the southern polar coronal hole. Throughout these large changes, the momentum flux normalized to 1 AU displays very little systematic variation. In addition, the bulk properties of the polar coronal hole solar wind are quite similar to those observed in high speed streams in the ecliptic plane at 1 AU. Coronal mass ejections and forward and reverse shocks associated with corotating interaction regions have also been observed at higher heliolatitudes, however they are seen less frequently with increasing southern heliolatitude. Ulysses has thus far collected data from 20° of nearly contiguous solar wind flows from the polar coronal hole. We examine these data for characteristic variations with heliolatitude and find that the bulk properties in general show very little systematic variation across the southern polar coronal hole so far.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768760
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  • 10
    Electronic Resource
    Electronic Resource
    Reconnection on open field lines ahead of coronal mass ejections (1995)
    Springer
    Space science reviews 72 (1995), S. 129-132 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Plasma and magnetic field signatures from 29 November 1990 indicate that the Ulysses spacecraft passed through a series of interplanetary structures that were most likely formed by magnetic reconnection on open field lines ahead of a coronal mass ejection (CME). This reconnection changed the magnetic topology of the upstream region by converting normal open interplanetary magnetic field into a pair of regions: one magnetically disconnected from the Sun and the other, a tongue, connected back to the Sun at both ends. This process provides a new method for producing both heat flux dropouts and counterstreaming suprathermal electron signatures in interplanetary space. In this paper we expand upon the 29 November case study and argue that reconnection ahead of CMEs should be less common at high heliolatitudes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00768768
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