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371.
Gülçin Kandemir 《Astrophysics and Space Science》1994,211(1):93-97
Ariel 4 satellite electron density data returned by the rf-capacitance probe on board are further investigated in order to seek any possible signature of the magnetic cusp in two different hemispheres during magnetically quiet periods at the 1972 vernal equinox. Ariel 4 electron density data covering the middle and high invariant magnetic latitudes at around 550 km altitude, for 91 days centered on the March 1972 equinox are employed. The data revealed a strong magnetic local time (MLT) dependence. The cusp signature was clearly in the Northern Hemisphere. 相似文献
372.
Can Battal Kilinç 《Astrophysics and Space Science》1994,222(1-2):171-179
In this paper cylindrically symmetric, inhomogeneous cosmological models with heat flux, viscous fluid and electromagnetic field are obtained. Various physical and geometrical properties of the models are also discussed. 相似文献
373.
T. Ataç 《Astrophysics and Space Science》1987,129(1):203-208
In this study, the statistical relationship between sunspots and major flares observed in the descending branch of the 20th and in the ascending branch of the 21st solar cycle is evaluated. It is found that the sunspots which produced these major flares are of the type Dki or Eki with magnetic class D and the largest magnetic field strength between 1600 and 2500 G. 相似文献
374.
Vieira L.E.A. Gonzalez W.D. Echer E. Guarnieri F.L. Prestes A. Gonzalez A.L.C. Santos J.C. Dal Lago A. Schuch N.J. 《Solar physics》2003,217(2):383-394
In this work we present a methodology to estimate the geomagnetic symmetric index (Sym) based on the wavelet analysis of the time series of the H component of the geomagnetic field measured at mid-latitude stations localized at Kakioka (KAK), Honolulu (HON), Hermanus (HER) and San Juan (SJG). A case study of the intense geomagnetic storm of 17–22 February 1999, caused by intense southward magnetic fields just behind an interplanetary shock driven by a magnetic cloud, is shown as an example of the procedure of derivation of the symmetric index and the capabilities of this analysis to improve the study of the coupling of the solar wind and the Earth's magnetosphere. Other examples are shown in order to demonstrate the applicability of the methodology to different magnetospheric conditions. It is shown that the long period variations of the symmetric index are linearly correlated to variations at the same periods of the H component of the geomagnetic field and that the contribution of short period variations to the symmetric index are biased by localized current systems such as the partial ring current and the field aligned currents. 相似文献
375.
Pierre Ocvirk Ariane Lançon Christophe Pichon Philippe Prugniel Damien Le Borgne Brigitte Rocca-Volmerange Michel Fioc Caroline Soubiran Eric Thiébaut 《Astrophysics and Space Science》2003,284(2):933-936
We present inversion techniques which aim at recovering the composite nature and the kinematics of a stellar population from
its high resolution absorption line spectrum. The originality of the combined inversion is its potential to recover both the
stellar content and the kinematics simultaneously. These techniques use new synthetic high resolution spectra produced by
PéGASE and minimization algorithms. We apply them to mock data representing the bulge and disk population of the inner region
of spiral galaxies.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
376.
Szegö Karoly Crifo Jean-François Rodionov Alexander V. Fulle Marco 《Earth, Moon, and Planets》2002,90(1-4):435-443
The cameras carried onboard the flyby missions to comet P/Halleyin 1986 imaged the near nuclear jet activity fromseveral spatial
directions. The observed, very structured near nucleardust jets were considered at that timeas the result of dust emission
from well localized active surface regions(without supporting 3-D model computations, however).Based on the first, recently
developed 3-D gas dynamical model ofP/Halley's activity,we have been shown that jet features can be reproduced assuming ahomogeneous
dusty icenucleus surface. The dust in the collisional near nuclear comais concentrated along the gas flow discontinuities
resulting from thecomplicated surface orography, creating the visual impression ofdust jets. We present here the results of
these calculations forthe near nucleus dust distributions,and we compare them with the direct observations made during thethree
Halley flybys (Vega 1, Vega 2, and Giotto). 相似文献
377.
378.
Edith Falgarone Pierre Hily-Blant François Levrier 《Astrophysics and Space Science》2004,292(1-4):89-101
This review, far from exhaustive, focuses on the specific properties of molecular clouds in their least condensed phase. Emphasis is placed on their connection with the diffuse medium, their multi-fractal characteristics and the diversity of their small-scale structure, where cold and dense gas may coexist with dilute and warm gas. Stuctures of essentially pure velocity origin are uncovered and seen as a possible signature of the intermittency of turbulence dissipation. 相似文献
379.
François Puel 《Celestial Mechanics and Dynamical Astronomy》1983,29(3):255-266
After reviewing known results on bounded motions in a central field and on the angle between two consecutive apocenters, we investigate the limit of the orbits as the pericenter tends to the origin. A ‘deflection’ of the almost rectilinear orbits is found which depends on the shape of the potential at the origin. We then study the rotation numbers of all, bounded motions in a field homogeneous inr. Finally on a few examples we show how to represent the set of bounded motions in an inhomogeneous field. 相似文献
380.
François Mignard 《Earth, Moon, and Planets》1981,24(2):189-207
In this paper we present an investigation on the tidal evolution of a system of three bodies: the Earth, the Moon and the Sun. Equations are derived including dissipation in the planet caused by the tidal interaction between the planet and the satellite and between the planet and the sun. Dissipation within the Moon is included as well. The set of differential equations obtained is valid as long as the solar disturbances dominate the perturbations on the satellite's motion due to the oblateness of the planet, namelya/R
e greater than 15, and closer than that point equations derived in a preceding paper are used.The result shows the Moon was closer to the Earth in the past than now with an inclination to the ecliptic greater than today, whereas the obliquity was smaller. Toward the past, the inclination to the Earth's equator begins decreasing to 12° fora/R
e=12 and suddenly grows. During the first stage the results are weakly dependant on the magnitude of the dissipation within the satellite, whereas the distance of the closest approach and the prior history are strongly dependent on that dissipation. In particular, the crossing of the Roche limit can be avoided. 相似文献