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| Titel |
Observational tests of the properties of turbulence in the Very Local Interstellar Medium |
| VerfasserIn |
S. R. Spangler, A. H. Savage, S. Redfield |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 17, no. 6 ; Nr. 17, no. 6 (2010-12-17), S.785-793 |
| Datensatznummer |
250013765
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| Publikation (Nr.) |
 copernicus.org/npg-17-785-2010.pdf |
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| Zusammenfassung |
| The Very Local Interstellar Medium (VLISM) contains clouds which consist of
partially-ionized plasma. These clouds can be effectively diagnosed via high
resolution optical and ultraviolet spectroscopy of the absorption lines they
form in the spectra of nearby stars. Information provided by these
spectroscopic measurements includes values for ξ, the root-mean-square
velocity fluctuation due to turbulence in these clouds, and T, the ion
temperature, which may be partially determined by dissipation of turbulence.
We consider whether this turbulence resembles the extensively studied and
well-diagnosed turbulence in the solar wind and solar corona. Published
observations are used to determine if the velocity fluctuations are primarily
transverse to a large-scale magnetic field, whether the temperature
perpendicular to the large scale field is larger than that parallel to the
field, and whether ions with larger Larmor radii have higher temperatures
than smaller gyroradius ions. We ask if the spectroscopically-deduced
parameters such as ξ and T depend on the direction on the sky. We also
consider the degree to which a single temperature T and turbulence
parameter ξ account for the spectral line widths of ions with a wide
range of masses. A preliminary examination of the published data shows no
evidence for anisotropy of the velocity fluctuations or temperature, nor
Larmor radius-dependent heating. These results indicate differences between
solar wind and Local Cloud turbulence. Possible physical reasons for these
differences are discussed. |
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