Search Results - (Author, Cooperation:J. Benkhoff)

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  1. 1
    Staff View
    Publication Date:
    2011-10-29
    Publisher:
    American Association for the Advancement of Science (AAAS)
    Print ISSN:
    0036-8075
    Electronic ISSN:
    1095-9203
    Topics:
    Biology
    Chemistry and Pharmacology
    Computer Science
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    http://www.aaas.org/

    Latest Papers from Table of Contents or Articles in Press
  2. 2
    G. Filacchione ; M. C. De Sanctis ; F. Capaccioni ; A. Raponi ; F. Tosi ; M. Ciarniello ; P. Cerroni ; G. Piccioni ; M. T. Capria ; E. Palomba ; G. Bellucci ; S. Erard ; D. Bockelee-Morvan ; C. Leyrat ; G. Arnold ; M. A. Barucci ; M. Fulchignoni ; B. Schmitt ; E. Quirico ; R. Jaumann ; K. Stephan ; A. Longobardo ; V. Mennella ; A. Migliorini ; E. Ammannito ; J. Benkhoff ; J. P. Bibring ; A. Blanco ; M. I. Blecka ; R. Carlson ; U. Carsenty ; L. Colangeli ; M. Combes ; M. Combi ; J. Crovisier ; P. Drossart ; T. Encrenaz ; C. Federico ; U. Fink ; S. Fonti ; W. H. Ip ; P. Irwin ; E. Kuehrt ; Y. Langevin ; G. Magni ; T. McCord ; L. Moroz ; S. Mottola ; V. Orofino ; U. Schade ; F. Taylor ; D. Tiphene ; G. P. Tozzi ; P. Beck ; N. Biver ; L. Bonal ; J. P. Combe ; D. Despan ; E. Flamini ; M. Formisano ; S. Fornasier ; A. Frigeri ; D. Grassi ; M. S. Gudipati ; D. Kappel ; F. Mancarella ; K. Markus ; F. Merlin ; R. Orosei ; G. Rinaldi ; M. Cartacci ; A. Cicchetti ; S. Giuppi ; Y. Hello ; F. Henry ; S. Jacquinod ; J. M. Reess ; R. Noschese ; R. Politi ; G. Peter
    Nature Publishing Group (NPG)
    Published 2016
    Staff View
    Publication Date:
    2016-01-14
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    http://www.nature.com/

    Latest Papers from Table of Contents or Articles in Press
  3. 3
    Staff View
    Publication Date:
    2015-08-01
    Publisher:
    American Association for the Advancement of Science (AAAS)
    Print ISSN:
    0036-8075
    Electronic ISSN:
    1095-9203
    Topics:
    Biology
    Chemistry and Pharmacology
    Computer Science
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    http://www.aaas.org/

    Latest Papers from Table of Contents or Articles in Press
  4. 4
    F. Capaccioni ; A. Coradini ; G. Filacchione ; S. Erard ; G. Arnold ; P. Drossart ; M. C. De Sanctis ; D. Bockelee-Morvan ; M. T. Capria ; F. Tosi ; C. Leyrat ; B. Schmitt ; E. Quirico ; P. Cerroni ; V. Mennella ; A. Raponi ; M. Ciarniello ; T. McCord ; L. Moroz ; E. Palomba ; E. Ammannito ; M. A. Barucci ; G. Bellucci ; J. Benkhoff ; J. P. Bibring ; A. Blanco ; M. Blecka ; R. Carlson ; U. Carsenty ; L. Colangeli ; M. Combes ; M. Combi ; J. Crovisier ; T. Encrenaz ; C. Federico ; U. Fink ; S. Fonti ; W. H. Ip ; P. Irwin ; R. Jaumann ; E. Kuehrt ; Y. Langevin ; G. Magni ; S. Mottola ; V. Orofino ; P. Palumbo ; G. Piccioni ; U. Schade ; F. Taylor ; D. Tiphene ; G. P. Tozzi ; P. Beck ; N. Biver ; L. Bonal ; J. P. Combe ; D. Despan ; E. Flamini ; S. Fornasier ; A. Frigeri ; D. Grassi ; M. Gudipati ; A. Longobardo ; K. Markus ; F. Merlin ; R. Orosei ; G. Rinaldi ; K. Stephan ; M. Cartacci ; A. Cicchetti ; S. Giuppi ; Y. Hello ; F. Henry ; S. Jacquinod ; R. Noschese ; G. Peter ; R. Politi ; J. M. Reess ; A. Semery
    American Association for the Advancement of Science (AAAS)
    Published 2015
    Staff View
    Publication Date:
    2015-01-24
    Publisher:
    American Association for the Advancement of Science (AAAS)
    Print ISSN:
    0036-8075
    Electronic ISSN:
    1095-9203
    Topics:
    Biology
    Chemistry and Pharmacology
    Computer Science
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    http://www.aaas.org/

    Latest Papers from Table of Contents or Articles in Press
  5. 5
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90–120 km altitude) of Venus can be used to investigate the energetics and to trace the circulation ...
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1038/nature06140

    Articles: DFG German National Licenses
  6. 6
    Spohn, T. ; Benkhoff, J.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0019-1035
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1016/0019-1035(90)90139-Z

    Articles: DFG German National Licenses
  7. 7
    Spohn, T. ; Benkhoff, J. ; Klinger, J. ; Grun, E. ; Kochan, H.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0273-1177
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/0273-1177(89)90251-2

    Articles: DFG German National Licenses
  8. 8
    Staff View
    ISSN:
    0273-1177
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/0273-1177(89)90252-4

    Articles: DFG German National Licenses
  9. 9
    Benkhoff, J. ; Boese, R. ; Klarner, F.-G. ; Wigger, A.E.

    Amsterdam : Elsevier
    Staff View
    ISSN:
    0040-4039
    Keywords:
    Repetitive Diels-Alder reactions ; bis-dienes ; bis-dienophiles ; endo-stereoselectivity
    Source:
    Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics:
    Chemistry and Pharmacology
    Type of Medium:
    Electronic Resource
    URL:
    http://linkinghub.elsevier.com/retrieve/pii/0040-4039(94)88165-0

    Articles: DFG German National Licenses
  10. 10
    Nentwig, W. ; Benkhoff, J. ; Gericke, D.
    Springer
    Published 1993
    Staff View
    ISSN:
    1432-1904
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Biology
    Chemistry and Pharmacology
    Natural Sciences in General
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF01168343

    Articles: DFG German National Licenses
  11. 11
    Boice, D. C. ; Benkhoff, J. ; Gladstone, G. R.
    Springer
    Published 1995
    Staff View
    ISSN:
    1573-0794
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Geosciences
    Physics
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1007/BF00612964

    Articles: DFG German National Licenses
  12. 12
    Benkhoff, J. ; Rauer, H.
    Springer
    Published 1997
    Staff View
    ISSN:
    1573-0794
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Geosciences
    Physics
    Notes:
    Abstract Sublimation of minor gases from ices inside of a porous comet nucleus strongly depends on the effective energy input. Our model meant to describe the gas flux inside and out of the porous nucleus has been used to study the influence of physical and structural parameters on the effective energy input. We solve the conservation equations for H2O and CO as the most abundant minor component of higher volatility under appropriate boundary conditions. From the calculations we obtain the gas flux from volatile, icy components inside the porous nucleus, temperature profiles, changes in relative chemical abundances, and the gas flux into the coma for each of the volatiles. We will show results from our calculations for a model comet in the orbit of Hale-Bopp (C/1995 O1). In this paper we focus on the energy balance at the surface. We will also relate measurements of molecule fluxes to available energies and try to provide hints about the evolutionary status of the comet.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1023/A:1006277417633

    Articles: DFG German National Licenses
  13. 13
    Huebner, W. F. ; Benkhoff, J.
    Springer
    Published 1997
    Staff View
    ISSN:
    1573-0794
    Keywords:
    Comet nucleus ; coma ; volatile ices
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Geosciences
    Physics
    Notes:
    Abstract One of the goals of comet research is the determination of the chemical composition of the nucleus because it provides us with the clues about the composition of the nebula in which comet nuclei formed. It is well accepted that photo-chemical reactions must be considered to establish the abundances of mother molecules in the coma as they are released from the comet nucleus or from distributed dust sources in the coma. However, the mixing ratios of mother molecules in the coma changes with heliocentric distance. To obtain the abundances in the nucleus relative to those in the coma, we must turn our attention to the release rates of mother molecules from the nucleus as a function of heliocentric distance. For this purpose, we assume three sources for the coma gas: the surface of the nucleus (releasing mostly water vapor), the dust in the coma (the distributed source of several species released from dust particles), and the interior of the porous nucleus (the source of many species more volatile than water). The species diffusing from the interior of the nucleus are released by heat transported into the interior. Thus, the ratio of volatiles relative to water in the coma is a function of the heliocentric distance and provides important information about the chemical composition and structure of the nucleus. Our goal is to determine the abundance ratios of various mother molecules relative to water from many remote-sensing observations of the coma as a function of heliocentric distance. Comet Hale-Bopp is ideal for this purpose since it has been observed using instruments in many different wavelength regions over large ranges of heliocentric distances. The ratios of release rates of species into the coma are than modeled assuming various chemical compositions of the spinning nucleus as it moves from large heliocentric distance through perihelion. Since the heat flow into the nucleus will be different after perihelion from that before perihelion, we can also expect different gas release rates after perihelion compared to those observed before perihelion. Since not all the data are available yet, we report on progress of these calculations.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1023/A:1006299217208

    Articles: DFG German National Licenses
  14. 14
    Staff View
    ISSN:
    1476-4687
    Source:
    Nature Archives 1869 - 2009
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Notes:
    [Auszug] Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright ‘dipole’ feature surrounded by a cold ‘collar’ at ...
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1038/nature06209

    Articles: DFG German National Licenses
  15. 15
    Benkhoff, J.
    Springer
    Published 1999
    Staff View
    ISSN:
    1572-9672
    Keywords:
    Comets ; Ices ; Energy Balance ; Molecular Flux
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract Surface temperature and the available effective energy strongly influence the mass flux of H2O and minor volatiles from the nucleus. We perform computer simulations to model the gas flux from volatile, icy components in porous ice-dust surfaces, in order to better understand results from observations of comets. Our model assumes a porous body containing dust, one major ice component (H2O) and up to eight minor components of higher volatility (e.g. CO, CH4, CH3OH, HCN, C2H2, H2S), The body's porous structure is modeled as a bundle of tubes with a given tortuosity and an initially constant pore diameter. Heat is conducted by the matrix and carried by the vapors. The model includes radially inward and outward flowing vapor within the body, escape of outward flowing gas from the body, complete depletion of less volatile ices in outer layers, and recondensation of vapor in deeper, cooler layers. From the calculations we obtain temperature profiles and changes in relative chemical abundances, porosity and pore size distribution as a function of depth, and the gas flux into the interior and into the atmosphere for each of the volatiles at various positions of the body in its orbit. In this paper we relate the observed relative molecular abundances in the coma of Comet C/1995 O1 (Hale-Bopp) and of Comet 46P/Wirtanen to molecular fluxes at the surface calculated from our model.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1023/A:1005246030600

    Articles: DFG German National Licenses
  16. 16
    Huebner, W.F. ; Benkhoff, J.
    Springer
    Published 1999
    Staff View
    ISSN:
    1572-9672
    Keywords:
    Coma ; Nucleus ; Heat Diffusion ; Gas Diffusion ; Mother Molecules
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract A major goal of comet research is to determine conditions in the outer solar nebula based on the chemical composition and structure of comet nuclei. The old view was to use coma abundances directly for the chemical composition of the nucleus. However, since the composition of the coma changes with heliocentric distance, r, the new view is that the nucleus composition msut be determined from analysis of coma mixing ratios as a function of r. Taking advantage of new observing technology and the early detection of the very active Comet Hale-Bopp (C/1995 O1) allows us to determine the coma mixing ratios over a large range of heliocentric distances. In our analysis we assume three sources for the coma gas: (1) the surface of the nucleus (releasing water vapor), (2) the interior of the porous nucleus (releasing many species more volatile than water), and (3) the distributed source (releasing gases from ices and hydrocarbon polycondensates trapped and contained in coma dust). Molecules diffusing inside the nucleus are sublimated by heat transported into the interior. The mixing ratios in the coma are modeled assuming various chemical compositions and structural parameters of the spinning nucleus as it moves in its orbit from large heliocentric distance through perihelion. We have combined several sets of observational data of Comet Hale-Bopp for H2O (from OH) and CO, covering the spectrum range from radio to UV. Many inconsistencies in the data were uncovered and reported to the observers for a reanalysis. Since post-perihelion data are still sparse, we have combined pre- and post-perihelion data. The resulting mixing ratio of CO relative to H2O as a function of r is presented with a preliminary analysis that still needs to be expanded further. Our fit to the data indicates that the total CO release rate (from the nucleus and distributed sources) relative to that of H2O is 30% near perihelion.
    Type of Medium:
    Electronic Resource
    URL:
    http://dx.doi.org/10.1023/A:1005289829692

    Articles: DFG German National Licenses