Effects of convection electric field on the thermal plasma flow between the ionosphere and the protonosphere

Dynamic behavior of the coupled ionosphere-protonosphere system in the magnetospheric convection electric field has been theoretically studied for two plasmasphere models. In the first model, it is assumed that the whole plasmasphere is in equilibrium with the underlying ionosphere in a diurnal average sense. The result for this model shows that the plasma flow between the ionosphere and the protonosphere is strongly affected by the convection electric field as a result of changes in the volume of magnetic flux tubes associated with the convective cross-L motion. Since the convection electric field is assumed to be directed from dawn to dusk, magnetic flux tubes expand on the dusk side and contract on the dawn side when rotating around the earth. The expansion of magnetic flux tubes on the dusk side causes the enhancement of the upward H⁺ flow, whereas the contraction on the dawn side causes the enhancement of the downward H⁺ flow. Consequently, the H⁺ density decreases on the dusk side and increases on the dawn side. It is also found that significant latitudinal variations in the ionospheric structures result from the L-dependency of these effects. In particular, the H⁺ density at 1000 km level becomes very low in the region of the plasmasphere bulge on the dusk side. In the second model, it is assumed that the outer portion of the plasmasphere is in the recovery state after depletions during geomagnetically disturbed periods. The result for this model shows that the upward H⁺ flux increases with latitude and consequently the H⁺ density decreases with latitude in the region of the outer plasmasphere. In summary, the present theoretical study provides a basis for comparison between the equatorial plasmapause and the trough features in the topside ionosphere.     

Continuation of periodic orbits: Three-dimensional circular restricted to the general three-body problem

It is proved that a periodic orbit of the three-dimensional circular restricted three-body problem can be continued analytically, when the mass of the third body is sufficiently small, to a periodic orbit of the three dimensional general three-body problem in a rotating frame. The above method is not applicable when the period of the periodic orbit of the restricted problem is equal to 2k (k any integer), in the usual normalized units. Several numerical examples are given.     

Existence of the continuations in theN-body problem

The method of obtaining the estimates of the maximalt-interval ( _–, ₊) on which the solution of theN-body problem exists and which is such that some fixed mutual distance (e. g. ₁₂) exceeds some fixed non-negative lower bound, for allt contained in ( _–, ₊), is considered. For given masses and initial data, the increasing sequences of the numbers _k , each of which provides the estimate ₊ > _k , are constructed. It appears that if ₊ = +, then .     

On transfer equation in a semi-infinite atmosphere with albedo ω>1

In this note we derive an exact solution of transfer equation in a plane-parallel semiinfinite atmosphere with albedo >1, by the method of Laplace transform and Wiener-Hopf technique. The emergent intensityI(0, ) is obtained in terms of theH ⁰-functionH ⁰() (Das Gupta, 1978) for which some good approximations are given. Intensity at any depth is also obtained.I(0, )/I(0, 0) is plotted in graphs against [0,1], and shows a maximum which drops and shifts towards the origin as increases.     

Photoelectric study of the δ Scuti star HR 1225

The periodogram analysis of theV observations of the Scuti star HR 1225 has been carried out. Two frequencies of 6.415 cd (P ₀=0 _. ^d 1558) and 8.418 cd (P ₁=0 _. ^d 1188) have been determined. The period ratio ofP ₁/P ₀=0.762 indicates radial pulsation. The absolute magnitude, effective temperature and mass of the star are derived to be 1 _. ^m 05, 7600 K and 1.9M , respectively.     

The enigma of helium and anomalous xenon

Isotopically anomalous xenon in chondrites is closely associated with low-Z noble gases, but there is no helium (or neon) in the noble gas component with normal xenon. The correlation of elemental and isotopic heterogeneities in meteoritic noble gases places stringent limits on the origin of isotopically anomalous elements in meteorites and on the formation of the solar system.     

A history of the determination of Pluto's mass

Lowell's value for the mass of Planet X was about seven times that of the Earth. Postdiscovery determinations of the mass of Pluto from analysis of the observed motions of Uranus and Neptune reduced this value to about one Earth mass. More extended analyses in the past 10 years have lowered this value to about one-tenth of an Earth mass. The mass so derived, however, fails to agree by a factor of 50 with that determined from the motion of the newly discovered satellite Charon. The discrepancy may arise from unmodeled effects in the motions of the outer planets.     

Proton-cyclotron instabilities in non-uniform loss-cone magnetospheric plasma

The waves, propagating nearly transverse to the ambient magnetic field, with frequencies near the harmonics of the proton-cyclotron frequency are studied in an inhomogeneous plasma with protons having loss-cone distributions. Three types of drift cyclotron instabilities have been studied: (i) non-flute instability; (ii) B-resonant instability; and (iii) non-resonant instability. Increases of loss-cone and density gradient increase the growth rates of all three instabilities. Increases in the positive temperature gradient and _t (ratio of thermal pressure of trapped protons to magnetic field pressure) have a stabilizing effect on the non-flute and non-resonant instabilities and a destabilizing effect on the B-resonant instability. The non-resonant instability has an interesting feature: a particular harmonic can be excited in two separate bands of unstable wave numbers. These instabilities can play an important role in the dynamics of the ring current and the inner edge of the plasma sheet region of the magnetosphere. The discrete turbulence generated by them would give rise to precipitation of protons on the auroral field lines, which may contribute to the excitation of diffuse aurora. These instabilities may be relevant to the observation of harmonic waves at 6R _E by Perrautet al. (1978).     

Absolute dimensions of TT Hydrae

The photometric elements of the Algol type binary TT Hydrae derived by the authors from theirUBV observations during 1973–77 have been combined with the spectroscopic elements given by Sanford (1937) and Sahade and Cesco (1946) to obtain the absolute dimensions of the system. It is found that the spectroscopic orbital elements given by Sanford represent the evolutionary status of the secondary component better than those of Sahade and Cesco. The primary appears to be an Al v main sequence star of mass and radius ∼2.3R _⊙. The secondary fills its Roche lobe; it can be represented by a K0iii star of mass and radius ∼6.0R _⊙. Better spectroscopic data are needed for confirmation of these results.     

On the convective instability of finitely conducting viscous model chromosphere

The convective stability of a simple model chromosphere, consisting of protons, electrons and hydrogen atoms in the ground state, has been studied in the presence of a vertically upward uniform magnetic field to include the effects of FLR, Hall-currents, finite conductivity and ionization. The ionization in the chromosphere is collisional and the recombination is radiative. It is found that the Schwarzchild criterion should necessarily be satisfied for the stability together with the condition thatv > 2v ₀, where is kinematic viscosity andv ₀ is gyroviscosity. Some special cases have also been investigated.