Motions in the solar atmosphere associated with the white light flare of 11 July 1978

Series of white light heliograms and oft- and on-band H filtergrams have been obtained, with an average spatial resolution of 1, to study the flare active McMath region 15403 on 11 July, 1978. A great number of accurate heliographic positions were determined for the umbrae, the white light flare patches and several bright H flare knots, as well as along the principal zero filament and an arch prominence. Using the measured heliographic coordinates of these objects their motions could be analyzed in some detail. The velocities of several different objects could be deduced from the coordinates. Since the heliocentric angle of the region was about 45°, the variation in apparent heliographic coordinates also enabled some variations in heights to be determined.It is pointed out that the flare when fully developed, consisted almost entirely of loops. The zero filament which was activated prior to the flare ran between two umbrae of common penumbra and opposite polarity, one belonging to an old, the other to a new spot group. The white light flare developed on both sides of the filament where it passed between these two umbrae; it was also the place where the flare started. Observational evidence appears to indicate that the erupted filament re-formed from below.An indication has been found that there was a link between the motion of some umbrae and the major flare occurrence.     

The main problem of lunar theory solved by the method of Brown

Brown's method for solving the main problem of lunar theory has been adapted for the computation by machine with the help of an algebraic processor. Brown's results are first recovered and refined. The solution is then expanded to include most terms of order nine. The terms in the series for the longitude and latitude are listed with an accuracy of 0.000 01 and of 0.000 001 for the parallax.This research was supported in parts by the National Science Foundation grant MCS 78-01425.     

Long term modulation of cosmic rays and inferable electromagnetic state in solar modulating region

It is demonstrated that the long term variation in cosmic ray intensity I(t) can be described by an integral equation,

$\text{I(t)=I}{}_{\mathrm{\infty }}\text{?}\text{∫}\text{0}\text{∞}\text{f(τ)S(t?τ)}\text{d}\text{τ}$

, which is derived from a generalization of Simpson's coasting solar wind model. A source function S(t?τ) is given by some appropriate solar activity index at a time t?τ(τ ? 0) and the characteristic functionf(τ)(?0 forτ ? 0) expresses the time dependence of the efficiency of the intensity depression due to solar disturbances represented by S(t ?τ) when the disturbances generated at the solar surface propagate through the modulating region with the solar wind. It is demonstrated further that the equation can be derived from the general diffusion-convection theory on some assumptions, and as a result, the source and characteristic functions can be related to diffusion coefficient and its transition in space. Assuming the sunspot number R (or two activity indices including R) as the source function, the characteristic function f(τ) [or f(τ)'s] is obtained with data of the cosmic ray intensity extended over several decades. Based on the theory, one can obtain from f(τ) the following physical quantities in space, such as the transition and life time of solar disturbances, the boundary of the modulating region, and the radial and time dependences of the diffusion coefficient, radial density gradient and modulated intensity of cosmic rays. Results deduced from the present analysis are consistent with those obtained directly or indirectly by space observations.     

Basaltic magmatism and the bulk composition of the moon

The lunar interior is comprised of two major petrological provinces: (1) an outer zone several hundred km thick which experienced partial melting and crystallization differentiation 4.4–4.6 b.y. ago to form the lunar crust together with an underlying complementary zone of ultramafic cumulates and residua, and (2) the primordial deep interior which was the source region for mare basalts (3.2–3.8 b.y.) and had previously been contaminated to varying degrees with highly fractionated material derived from the 4.4–4.6 b.y. differentiation event. In both major petrologic provinces, basaltic magmas have been produced by partial melting. The chemical characteristics and high-pressure phase relationships of these magmas can be used to constrain the bulk compositions of their respective source regions.Primitive low-Ti mare basalts (e.g., 12009, 12002, 15555 and Green Glass) possessing high normative olivine and high Mg and Cr contents, provide the most direct evidence upon the composition of the primordial deep lunar interior. This composition, as estimated on the basis of high pressure equilibria displayed by the above basalts, combined with other geochemical criteria, is found to consist of orthopyroxene + clinopyroxene + olivine with total pyroxenes > olivine, 100 MgO/(MgO + FeO) = 75–80, about 4% of CaO and Al₂O₃ and 2× chondritic abundances of REE, U and Th. This composition is similar to that of the earth's mantle except for a higher pyroxene/olivine ratio and lower 100 MgO/(MgO + FeO).The lunar crust is believed to have formed by plagioclase elutriation within a vast ocean of parental basaltic magma. The composition of the latter is found experimentally by removing liquidus plagioclase from the observed mean upper crust (gabbroic anorthosite) composition, until the resulting composition becomes multiply saturated with plagioclase and a ferromagnesian phase (olivine). This parental basaltic composition is almost identical with terrestrial oceanic tholeiites, except for partial depletion in the two most volatile components, Na₂ and SiO₂. Similarity between these two most abundant classes of lunar and terrestrial basaltic magmas strongly implies corresponding similarities between their source regions. The bulk composition of the outer 400 km of the Moon as constrained by the 4.6-4.4 b.y. parental basaltic magma is found to be peridotitic, with olivine > pyroxene, 100 MgO/ (MgO + FeO) 86, and about 2× chondritic abundances of Ca, Al and REE. The Moon thus appears to have a zoned structure, with the deep interior (below 400 km) possessing somewhat higher contents of FeO and SiO₂ than the outer 400 km. This zoned model, derived exclusively on petrological grounds, provides a quantitative explanation of the Moon's mean density, moment of inertia and seismic velocity profile.The bulk composition of the entire Moon, thus obtained, is very similar to the pyrolite model composition for the Earth's mantle, except that the Moon is depleted in Na (and other volatile elements) and somewhat enriched in iron. The similarity in major element composition extends also to the abundances of REE, U and Th. These compositional similarities, combined with the identity in oxygen isotope ratios between the Moon and the Earth's mantle, are strongly suggestive of a common genetic relationship.     

Tridiurnal variations in cosmic-ray intensity

The tridiurnal wave in cosmic-ray intensity expected from a free space anisotropy is theoretically calculated for different cosmic-ray stations which are characterized by different shapes of asymptotic cones of acceptance. The amplitude A and the time of maximum Tmax are given for latitude dependence of the form cosⁿ λ and rigidity dependence of the form $\text{R}{}^{\mathrm{\beta }}\text{exp (?(R?}\text{1}\text{R}{}_0\text{))}$, where λ and R are the latitude and rigidity respectively and n, β, R₀ are constants. The values of A and Tmax, are calculated for different values of n, β and R₀ for each station. The dependence of A and Tmax on the anisotropy parameters is studied for the proper selection of cosmic-ray stations whose data may be used in determining these parameters.Available experimental data were used to find the observed amplitudes of the tridiurnal variations at five stations using power spectrum analysis with hanning applied on the averaged trains. Minimum variance analysis of the theoretical and experimental amplitudes showed that β has a value between 1 and 2, R₀ greater than 100 GV and n smaller than 3.     

A model for thinning of the plasma sheet

A one-dimensional model for thinning of the plasma sheet is developed on the basis of launching a fast mode MHD rarefaction wave propagating in the tailward direction along the plasma sheet. Behind the rarefaction wave the pressure is reduced, leading to thinning of the plasma sheet and also to an Earthward plasma flow with a speed on the order of the sound speed a₀. The plasma sheet thickness is reduced by a factor of 2 if an Earthward plasma flow speed of 0.8a₀ is induced. The predictions of the model are in reasonable agreement with observations.     

Unsteady MHD flow past a porous plate with step function change in suction at slip flow regime

Unsteady two-dimensional hydromagnetic flow of an electrically conducting viscous incompressible fluid past a semi-infinite porous flat plate with step function change in suction velocity is studied allowing a first order velocity slip at the boundary condition. The solution of the problem is obtained in closed form and the results are discussed with the aid of graphs for various parameters entering in the problem.Notations B intensity of magnetic field - H magnetic field parameter,H=(M+1/4)^1/2–1/2 - h rarefaction parameter - L ₁ slip coefficient; ;I, mean free path of gas molecules;f, Maxwell's reflection coefficient - M magnetic field parameter - r suction parameter - t time - t dimensionless time - u velocity of the fluid - u dimensionless velocity of the fluid - U velocity of the fluid at infinity - v suction velocity - v ₁ suction velocity att<=0 - v ₂ suction velocity att>0 - x distance parallel to the plate - y distance normal to the plate - y nondimensional distance normal to the plate - v kinematic viscosity - electric conductivity of the fluid - density of the fluid - shear stress at the wall - nondimensional shear stress at the wall - erf error function - erfc complementary error function