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  • 1
    Electronic Resource
    Electronic Resource
    The role of Lyman-α photons in the interstellar medium (1976)
    [s.l.] : Nature Publishing Group
    Nature 264 (1976), S. 44-45 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The electrostatic charge on grains is an important parameter which influences grain-plasma interactions, and also, probably, the heating rate of the interstellar medium. The mean equilibrium charge on grains for several likely grain materials is expected to be determined by a balance between ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/264044a0
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  • 2
    Electronic Resource
    Electronic Resource
    Charged dust grains and excitation of rotational levels of interstellar molecular hydrogen (1975)
    [s.l.] : Nature Publishing Group
    Nature 254 (1975), S. 203-205 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Since most interstellar dust partktes a*e beMeved to originate in the atmospheres of cool Carbon or Mira-type stars, the velocity of their injection into interstellar clouds is 108cms"1 (ref. 7). The velocity spectrum. o£ iMersleiiar grains resting from the slowing of such fast gFaaum ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/254203a0
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  • 3
    Electronic Resource
    Electronic Resource
    On the variation of specific angular momentum among Main Sequence stars (1971)
    Springer
    Astrophysics and space science 13 (1971), S. 234-248 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The specific angular momentum is found to vary with mass for earlier and later-type Main Sequence stars. Of various plausible causes, the difference in the interior density distribution of earlier and later-type stars is not sufficient enough to explain the difference either in angular momentum or in its gradient between earlier and later-type stars. The non-rigid rotation, however, may account for this difference in specific angular momentum as well as its gradient, if faster angular velocity in the interior for later-type and/or slower angular velocity for earlier-type stars than the surface value is allowed. A few other possibilities have also been briefly considered to understand this difference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656330
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular hydrogen in intercloud medium (1977)
    Springer
    Astrophysics and space science 49 (1977), S. 217-227 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We discuss the formation of molecular hydrogen on the surfaces of grains in a hot intercloud medium, by the process of chemisorption of hydrogen atoms on graphite grains. It is suggested that the molecular hydrogen observed towards stars with low reddening, may be located in the intercloud medium towards these stars. A comparison of the observed population distributions of H2 with the theoretical calculations shows that the observations are in the main consistent with a gas kinetic-temperature ∼8000 K and densities about 0.1 to 1 cm−3, parameters which are appropriate to the intercloud phase of the two phase model of the interstellar medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00647086
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  • 5
    Electronic Resource
    Electronic Resource
    Elemental abundance enhancement in cosmic rays and their relation to interstellar depletion (1981)
    Springer
    Astrophysics and space science 77 (1981), S. 521-527 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have shown that a correlation exists between the enhancement of abundance of heavy nuclei in cosmic rays and their depletion in interstellar space. A correlation also exists between the abundance enhancement and condensation temperature. We suggest that these correlations imply that much of the heavy nuclei content of cosmic rays may come from grains. A possible model is that grains in star-cloud complexes are accelerated to injection energies by radiation pressure in a supernova explosion and, subsequently, the grain debris is accelerated by shocks to cosmic ray energies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00649477
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  • 6
    Electronic Resource
    Electronic Resource
    On the production of positive molecular ions in cometary comas (1977)
    Springer
    Astrophysics and space science 50 (1977), S. 163-171 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Positively charged molecular ions, such as H2O+, which have been observed in cometary. comas, may be efficiently produced by the evaporation of positively charged clathrate grains of radii in the range ∼10−6–10−5 cm. Such grains may be expelled from nuclei of comets, along with gaseous molecules. Grain charging occurs via interaction with solar ultraviolet photons and/or solar wind protons. Observational data on the total quantities as well as the distributions of H2O and H2O+ in cometary comas are shown to be in accord with detailed model calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00648528
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrocarbon molecules in carbon stars (1975)
    Springer
    Astrophysics and space science 35 (1975), S. L41 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that the 10–13 μ band observed in the spectra of some carbon stars could arise from simple hydrocarbon molecules, especially of the type C n H 2n . These molecules could be present in circumstellar dust shells which are responsible for the 1000 K black-body excess observed for these stars, and the emission band is produced by collisional excitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00637011
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  • 8
    Electronic Resource
    Electronic Resource
    Population of excited rotational levels of interstellar H2 (1975)
    Springer
    Astrophysics and space science 36 (1975), S. 281-289 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The population of the rotational levels of vibrational and electronic ground state of interstellar H2 has been calculated; different possible excitation and de-excitation mechamisms including the ultraviolet pumping and formation and destruction of molecules have been considered. The values of temperature, density and radiation field towards ζ Oph, ɛ Per and ζ Pup have been obtained by comparing the theoretical distributions with the observations. The results indicate the presence of a high temperature low density diffuse cloud towards ζ Pup and low temperature high density clouds towards ζ Oph and ɛ Per. The results of this work were presented at the February, 1974 meeting of the Astronomical Society of India (Joshi and Tarafdar, 1974).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645254
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  • 9
    Electronic Resource
    Electronic Resource
    Population of excited rotational levels of HD and CO in interstellar clouds (1975)
    Springer
    Astrophysics and space science 36 (1975), S. 291-301 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Populations of the rotational levels of vibrational and electronic ground state of interstellar HD and CO have been calculated. Ultraviolet pumping and molecular formation have been found to be very important in the case of HD but not so in CO, the population distribution of which is mainly governed either by 3 K or by collisional excitation. The population inversion has been found to occur in HD but not in CO, the excitation temperatures of which pass through maximum for large ultraviolet flux. The population inversion at large density does not occur in HD, probably due to neglect of multipole collision. The observation of HD and CO in the excited states may be possible for suitable values of density and ultraviolet flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645255
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of suprathermal grains (1976)
    Springer
    Astrophysics and space science 39 (1976), S. 19-30 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Grains ejected from stars at velocities of ∼ 107 cm s−1 and/or grains accelerated by the pressure of starlight in the intercloud medium to velocities in the range 2×106–107 cm s−1 are slowed to velocities of about 2×105 cm s−1 in a typical interstellar cloud. The interaction of fast grains with gas atoms as they are slowed in clouds could provide (a) the dominant heat source for interstellar clouds; (b) sites for molecule formation; and (c) a mechanism of providing a pressure balance between clouds and the intercloud medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00640506
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