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  • Articles: DFG German National Licenses  (5)
  • 1995-1999  (5)
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  • Articles: DFG German National Licenses  (5)
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Composition of the Volatile Material in Halley's Coma from In Situ Measurements (1999)
    Springer
    Space science reviews 90 (1999), S. 3-18 
    Details
    ISSN: 1572-9672
    Keywords: P/Halley ; Volatiles ; Radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The investigation of the volatile material in the coma of comets is a key to understanding the origin of cometary material, the physical and chemical conditions in the early solar system, the process of comet formation, and the changes that comets have undergone during the last 4.6 billion years. So far, in situ investigations of the volatile constituents have been confined to a single comet, namely P/Halley in 1986. Although, the Giotto mission gave only a few hours of data from the coma, it has yielded a surprising amount of new data and has advanced cometary science by a large step. In the present article the most important results of the measurements of the volatile material of Halley's comet are summarized and an overview of the identified molecules is given. Furthermore, a list of identified radicals and unstable molecules is presented for the first time. At least one of the radicals, namely CH2, seems to be present as such in the cometary ice. As an outlook to the future we present a list of open questions concerning cometary volatiles and a short preview on the next generation of mass spectrometers that are being built for the International Rosetta Mission to explore the coma of Comet Wirtanen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005256607402
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The solar WIND and suprathermal ion composition investigation on the WIND spacecraft (1995)
    Springer
    Space science reviews 71 (1995), S. 79-124 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Solar Wind and Suprathermal Ion Composition Experiment (SMS) on WIND is designed to determine uniquely the elemental, isotopic, and ionic-charge composition of the solar wind, the temperatures and mean speeds of all major solar-wind ions, from H through Fe, at solar wind speeds ranging from 175 kms−1 (protons) to 1280 kms−1 (Fe+8), and the composition, charge states as well as the 3-dimensional distribution functions of suprathermal ions, including interstellar pick-up He+, of energies up to 230 keV/e. The experiment consists of three instruments with a common Data Processing Unit. Each of the three instruments uses electrostatic analysis followed by a time-of-flight and, as required, an energy measurement. The observations made by SMS will make valuable contributions to the ISTP objectives by providing information regarding the composition and energy distribution of matter entering the magnetosphere. In addition SMS results will have an impact on many areas of solar and heliospheric physics, in particular providing important and unique information on: (i) conditions and processes in the region of the corona where the solar wind is accelerated; (ii) the location of the source regions of the solar wind in the corona; (iii) coronal heating processes; (iv) the extent and causes of variations in the composition of the solar atmosphere; (v) plasma processes in the solar wind; (vi) the acceleration of particles in the solar wind; and (vii) the physics of the pick-up process of interstellar He as well as lunar particles in the solar wind, and the isotopic composition of interstellar helium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00751327
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The Toroidal Imaging Mass-Angle Spectrograph (TIMAS) for the polar mission (1995)
    Springer
    Space science reviews 71 (1995), S. 497-530 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The science objectives of the Toroidal Imaging Mass-Angle Spectrograph (TIMAS) are to investigate the transfer of solar wind energy and momentum to the magnetosphere, the interaction between the magnetosphere and the ionosphere, the transport processes that distribute plasma and energy throughout the magnetosphere, and the interactions that occur as plasma of different origins and histories mix and interact. In order to meet these objectives the TIMAS instrument measures virtually the full three-dimensional velocity distribution functions of all major magnetospheric ion species with one-half spin period time resolution. The TIMAS is a first-order double focusing (angle and energy), imaging spectrograph that simultaneously measures all mass per charge components from 1 AMU e−1 to greater than 32 AMU e−1 over a nearly 360° by 10° instantaneous field-of-view. Mass per charge is dispersed radially on an annular microchannel plate detector and the azimuthal position on the detector is a map of the instantaneous 360° field of view. With the rotation of the spacecraft, the TIMAS sweeps out very nearly a 4π solid angle image in a half spin period. The energy per charge range from 15 eV e−1 to 32 keV e−1 is covered in 28 non-contiguous steps spaced approximately logarithmically with adjacent steps separated by about 30%. Each energy step is sampled for approximately 20 ms;14 step (odd or even) energy sweeps are completed 16 times per spin. In order to handle the large volume of data within the telemetry limitations the distributions are compressed to varying degrees in angle and energy, log-count compressed and then further compressed by a lossless technique. This data processing task is supported by two SA3300 microprocessors. The voltages (up to 5 kV) for the tandem toroidal electrostatic analyzers and preacceleration sections are supplied from fixed high voltage supplies using optically controlled series-shunt regulators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00751339
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Rare Atoms, Molecules and Radicals in the Coma of P/Halley (1999)
    Springer
    Space science reviews 90 (1999), S. 253-268 
    Details
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have searched for rare molecules and radicals in the coma of P/Halley using the ion data obtained by IMS-Giotto. Whereas our established methods were used in the ionosphere, a new model was developed for the interpretation of the ion data in the outer coma. Ne/H2O 〈 1.5 × 10-3 was determined in the coma of the comet. Upper limits for the production of Na were derived from the very low abundance of Na+. Methyl cyanide and (probably) ethyl cyanide were identified with abundances of CH3CN/H2O = (1.4 ± .6) × 10-3 and C2H5CN/H2O = (2.8 ± 1.6) × 10-4. These results and upper limits for other N-bearing species confirm that nitrogen is depleted in the Halley material. C4H was identified and a point source strength of C4H/H2O = (2.3 ± .8) × 10-3 was derived. Our upper limit for C3H is lower than the abundance of C4H. This is in agreement with the enhanced abundances of CnH species with even numbers of C-atoms found in interstellar molecular clouds, suggesting that the C4H in Halley was synthesized under molecular cloud conditions. Thus, C4H and other organics with unpaired electrons may turn out to be indicators for a molecular cloud origin of cometary constituents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005266619214
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    CELIAS - Charge, Element and Isotope Analysis System for SOHO (1995)
    Springer
    Solar physics 162 (1995), S. 441-481 
    Details
    ISSN: 1573-093X
    Keywords: SOHO ; Solar Wind ; Solar Energetic Particles ; Composition Measurements ; Time-of-Flight Spectrometer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The CELIAS experiment on SOHO is designed to measure the mass, ionic charge and energy of the low and high speed solar wind, of suprathermal ions, and of low energy flare particles. Through analysis of the elemental and isotopic abundances, the ionic charge state, and the velocity distributions of ions originating in the solar atmosphere, the investigation focuses on the plasma processes on various temporal and spatial scales in the solar chromosphere, transition zone, and corona. CELIAS includes 3 mass- and charge-discriminating sensors based on the time-of-flight technique: CTOF for the elemental, charge and velocity distribution of the solar wind, MTOF for the elemental and isotopic composition of the solar wind, and STOF for the mass, charge and energy distribution of suprathermal ions. The instrument will provide detailed in situ diagnostics of the solar wind and of accelerated particles, which will complement the optical and spectroscopic investigations of the solar atmosphere on SOHO. CELIAS also contains a Solar Extreme Ultraviolet Monitor, SEM, which continously measures the EUV flux in a wide band of 17 – 70 nm, and a narrow band around the 30.4 nm He II line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00733436
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    Paper (German National Licenses)
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