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Vladimir A. Osherovich Erast B. Gliner Israel Tzur Michael L. Kuhn 《Solar physics》1985,97(2):251-266
A nonpolytropic model of a polar coronal hole at 2 R
R 5 R
is constructed. Our main assumptions are: (1) the magnetic structure of the Sun can be described by a combination of dipole-like and radial fields; (2) in the magnetically dominated region [(v
2/2) < (B
2/8)] the influence of the outflow on the magnetic structure is negligible. The magnetic and thermodynamic structures are obtained by solving the force balance equation for plasma with the observationally derived electron density. Profiles of velocities in the acceleration regime are presented and the influence of the outflow on the thermodynamic structure of the solar corona above the polar region is discussed.This paper is the first part of a joint project of the Space Environment Laboratory, the Joint Institute for Laboratory Astrophysics, and the High Altitude Observatory, NCAR. The second paper by Munro and Tzur is in preparation.Work done while at the Space Environment Laboratory, NOAA, ERL, Boulder, CO 80303, U.S.A.1982–83 Visiting Fellow at the Joint Institute for Laboratory Astrophysics, National Bureau of Standards and University of Colorado.The National Center for Atmospheric Research is sponsored by the National Science Foundation.Visitor at NCAR. 相似文献
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In this short paper we examine whether the measurement of Doppler shifts in the solar light reflected off an asteroid surface may improve the accuracy of the determined orbit. Our results suggest it will be worthwhile to use high‐resolution spectrographs, of the exoplanet‐hunting type, to measure those Doppler shifts. Spectroscopic Doppler shifts might improve the accuracy of Earth‐impact predictions, help to recover “lost” near‐Earth objects, and may also significantly enhance the knowledge about dynamics of the Kuiper belt. Future high‐resolution spectrographs on the VLT and the E‐ELT may thus have an important role in studies of Solar‐System dynamics and kinematics. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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A numerical model is used to simulate the buildup of an electric field from below the Venusian cloud layer to the surface. The steady-state profiles of the ion concentration, net space charge, diffusion and conduction current, and electric field are calculated. Two electric field sources are considered. The first is that produced by the higher diffusivity of positive ions relative to negative ions, which results in charging the surface with a net positive charge. The results show that the magnitude of the electric field and the net space charge developed near the surface are mainly dependent on the mixing conditions in the boundary layer. However, even in the case of relatively strong mixing, the maximum electric field is found to be 1.5 V m?1 and it decays rapidly above 100 m. The second source of an electric field is assumed to be charge separation inside Venusian clouds. A steady-state conduction current in the region below the layer of clouds which represents the intensity of charge separation inside the clouds is used as a parameter. When this parameter is assumed to be 10?12 A m?2, which is about the fair-weather conduction current in the atmosphere of Earth, an electric field of 5 kV m?1 is developed near the surface. This electric field exists up to a few kilometers, decreases by an order of magnitude at about 20 km, and then decays rapidly. 相似文献
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