Secondary production of antiprotons in cosmic radiation

A reliable representation to the invariant cross-section for the production of antiprotons ( ) in inclusive reactions has been obtained, which fits the data extremely well from threshold to ISR energies. Using this, the production spectrum of by cosmic ray interaction with interstellar gas is calculated and is compared with other existing calculations. The equilibrium spectrum in the Galaxy has been derived from about 100 MeV to a few hundred GeV in kinetic energy using Leaky Box Model for the propagation of cosmic rays, by taking into account all energy loss processes. It is found that /P ratio calculated here is very much smaller than the observed ratio. In view of the fact that this excess of observed /P ratio is much larger than the measured upper limits on the fraction of antimatter in the form of antinuclei, the excess /P ratio has not been attributed to the existence of antimatter. Instead, it is shown that Closed Galaxy Model for the propagation of cosmic rays predicts more antiprotons than observed. Therefore, it is suggested that if cosmic rays contain about 50% new component of local origin, the resulting Closed Galaxy Model explains well the observations. The present calculations also predict too small a flux of below a few hundred MeV to make this energy region ideally suited to look for antiprotons of primordial origin.     

Effect of central condensation on the modes of nonradial oscillations of stellar models

Modes of nonradial oscillations of six composite polytropic models have been investigated numerically to study the effect of central condensation parameter being the density at the centre and the mean density of a stellar model) on the modes of nonradial oscillations of stellar models.     

Propagating of sound and thermal waves in a reacting fluid

The propagation of linear sound and thermal waves in a reacting fluid, in which the heating and cooling processes can be represented by a heat-loss functionL(, T, is studied. A complex dispersion relation is found, from which the phase velocity and the scale length for damping (or amplification), of the above two-wave mode are calculated Wave amplification may occur in reacting locally stable fluids. Results are applied to a hydrogen plasma model assumed to be heated at a non-specified constant rate and cooled by recombination, excitation, and ionization by collisions, and free-free transitions. The phase velocity , the scale-length for damping , and the relevant relaxation times are calculated as functions of the dimensionless frequency , for temperatures ranging from those at which the hydrogen plasma is neutral to those at which it becomes completely ionized.     

The spherically-symmetrical trajectories of spin particles in the Schwarzschild field

The motion of spin particles in the Schwarzschild field is examined in this paper. It is shown that Mathisson-Papapetrou equations under additional conditions , where is the Lie derivative of the Killing vector _j , permit only radial motion, motion in the equatorial plane and in the equilibrium points. All these types of motion are considered more in detail.     

Charged particle diffusion in the presence of Alfvén waves: The perpendicular particle flux

The diffusion of charged particles through a weak stochastic electro-magnetic field which is superimposed on a constant background magnetic field is considered. The stochastic electromagnetic fields are assumed to consist of unpolarized Alfvén waves propagating at arbitrary angles to the direction . When the Alfvén waves are propagating in directions other than and the particle gyro-radius,r _g, is sufficiently large (but may be smaller than the correlation length of the stochastic fields) it is shown that the particle flux perpendicular to the direction is , wherev is the particle speed andf the particle density. The expression forK differs from those calculated by previous authors. For small particle gyro-radii the flux S has a different functional form and is identical to that found by Urch (1977) to describe particle diffusion when the Alfvén waves only propagate in the direction .     

The compton effect in the chromosphere,II

The red shift and central intensity are given for eleven spectral lines having an observed reduced equivalent widthV ranging fromV=15 toV=200. The computations have been repeated for eight values of the scattering thickness of the chromosphere, from to . A theoretical interpretation of measurements in the Sun is also given.     

Fourier analysis of the light curves of eclipsing variable stars

The aim of the present paper is to find the eclipse perturbations, in the frequency-domain, of close eclipsing systems exhibiting partial eclipses.After a brief introduction, in Section 2 we shall deal with the evaluation of thea _n ^(l) integrals for partial eclipses and give them in terms ofa ₀ ⁰ ,a ₀ ⁰ (of the associated -functions) and integrals; while Section 3 gives the eclipse perturbations arising from the tidal and rotational distortion of the two components. The are given for uniformly bright discs (h=1) as well as for linear and quadratic limb-darkening (h=2 and 3, respectively).Finally, Section 4 gives a brief discussion of the results and the way in which they can be applied to practical cases.     

Vibrational transition probabilities,\bar r-centroids and morse PE-curves for SiS

Vibrational transition probabilities-namely, Franck-Condon factors and -centroids-have been evaluated using an approximate analytical method for theD-X system of SiS. Morse potential energy curves forD ¹ andX ¹⁺ states of SiS have been constructed using the latest spectroscopic data. The value of -centroids for the band have been found to decrease linearly with the corresponding wavelength.     

Steady wave model of spiral galaxies and its application in cosmogony

The model is based on the assumption that logarithmic spiral arms of most spiral galaxies are due to the totating density wave obeying the steady wave equation . It is shown that this equation accounts also for the so-called Titius-Bode's law in the solar system.     

Static spherical configurations of cold matter in the Einstein-Cartan theory of gravitation

We investigate static, spherical configurations of cold catalized matter in the Einstein-Cartan theory of gravitation. Assuming that density of spin is proportional to the number density of baryonsn and using an equation of state of a degenerate, relativistic Fermi gas, we numerically integrated the relativistic equation of equilibrium. We have also studied the stability of those configurations. Configurations with central number densityn _c such that where is the effective pressure, are very similar to general relativistic configurations with the same central density. In the Einstein-Cartan theory there exists another disjoint family of equilibrium configurations for which but . Those configurations have very small masses 10^–6 g and raddi 10^–34 cm and are unstable.Supported in part by Research Grant MR-I-7.     

Close Binary System Go Cygnus: Standard Ubv Observations and Light Curve Analysis

Standard UBV light curves of eclipsing binary star GO CYGNUS havebeen presented. These light curves indicate a Lyrae typevariations with circular orbit. The Light curve analysis have beencarried out on three colours U, B and V. The results obtained fromthese analysis represent an occultation solution with r r =1.24.     

Der offene sternhaufen NGC 2362

The very young open star cluster NGC 2362 was investigated by the strip method on charts of two photographs taken with the 1-m Schmidt telescope of the European Southern Observatory. Up to the limiting magnitudeM _v ^* =5 _. ^m 8 the cluster contains 100 stars and can be described by the Gaussian density law (6). Further results are: Mass = 246 , central mass density ₀ = 43.1 = 246 pc^-3 , radiusR2.6 pc, mean velocity of the stars = 0.64 km s^–1.

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Mitteilungen Serie A.     

Some comments on the asymptotic limit of antiproton-proton flux ratio at the top of the atmosphere

Using the leaky-box model the upper limit of the antiproton-proton flux ratio at the top of the atmosphere has been estimated from the latest primary nucleon spectrum and accelerator data on inclusive reactions. The estimated value of flux ratio comes out to be (3.6±0.3)×10^–4 is in accord with the previous results but still far from the measurements.     

Epstein weight functions for non-radial oscillations of polytropes

Weight functions for the determination of the periods of linear adiabatic non-radial oscillations have been calculated in the same manner as Epstein's classic treatment of purely radial oscillations. Quadrupole (l=2) oscillations for thef and lower orderp andg-modes were considered. One group of static models were polytropes in the range 1.0n4.0 with ; thus included were configurations that were convectively stable, unstable and neutrally stable throughout. Another group consisted ofn=3.0 polytropes with convective shells or convective cores; ₁ was set at different values in each region in order to produce stability ( ) or instability ( ). The weight function provides a pictorial means for assessing the relative importance of each region of a given static model with respect to generating a given non-radial mode.     

The light curved in the CM field

In this paper we introduce the CM field in Sections 2 and 3 based on the paper by Wang and Peng (1985), and calculate the light curved in the CM field in Section 4. The result shows thatP makes _CM larger than _C at , and smaller at . Under a special circumstance which source, CM lens, and observer are in the same line, if we get | ₀₌₀ , and | _=/2 , we can determine theP(M) andQ(M) of the CM lens,M is the mass of the CM lens.     

On the structure and mass of the galactic halo

On the basis of a globular cluster study a crude estimate of the total mass of the galactic halo within 20 kpc from the centre is done. It gives a minimal halo mass of the order of , yielding possibilities for a mass as large as . The content of the interstellar matter in the halo is estimated too. It is found that the gas content is a few percents the minimal mass, the gas temperature is very high — about 1×10⁶ K, the magnetic field weak — about 0.25 nT. A weak nonthermal radio emission might be expected from such a halo.     

Evolution of galaxies: One-zone model with a birth-rate stellar function depending on gas density and temperature

In this paper closed one-zone models with a birth-rate stellar function depending on gas density and temperature are built up, in order to make a zeroth order approximation of thermo-chemical evolution of galaxies. To get a more realistic picture, the models are allowed first to expand with the universe and then to contract according to three successive time-scales, in order to simulate violent relaxation, rapid contraction, and slow contraction processes.Star formation occurs according to a birth-rate (m, t) _g ⁿ T ^r m ^p ( _g , gas density;T, gas temperature; andm, star mass), which reproduces the usual Schmidt-type law in the limitr0. Further we suppose that synthesized metals and helium are instantaneously mixed when returned to gas component at star death, and that relative metal abundances are time-independent: ( any element heavier than He, ). An energy fraction of each typical supernova event is assumed to heat interstellar medium, which is also though always to maintain a steady state.Under these hypotheses it becomes possible to use the interstellar cooling function of Dalgarno and McCray (1972), which is related to a special cosmic abundance of elements, to express analytically an interstellar cooling function related to any abundance. At this stage, numerical computations are performed up to about 12 Gy and the results analyzed in order to reproduce some morphological features observed in the galaxy, namely: (i) the extreme scarcity of stars with nearly zero metal content; (ii) the metal content and mass fraction of halo stars; (iii) the metal content and mass fraction of disk stars; and (iv) the ratio of the present-day birth-rate to the past birth-rate averaged over the age of the disk. It is found that a whole class of theoretical models exist, with slope of the mass spectrum between –2.5 and –2.6, which range from a Schmidt's law limitn=1.3 andr=0 to the opposite limitn=0 andr=–1.2, and are able to fit more or less at the same extent the observations mentioned above. On the analysis of further computations, it is also shown that an universal birth-rate stellar function is in contradiction with neither a dynamical hystory starting from the initial expansion of proto-galaxies, nor a morphological sequence where the amount of angular momentum is the only free parameter for any given mass, at least for what concerns spiral types. Finally, possible refinements for future work are briefly outlined.     

Die Mittleren Geschwindigkeiten Der Sterne In 58 Kugelförmigen Sternhaufen

The mean velocities of the stars in 58 globular clusters are derived from the photometric measurements of Kron and Mayall (1960). The mass-visual brightness ratio is used. The velocities are falling in the interval 2.9v11.6 km s^–1, their mean value is 6.75 km s^–1.

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Mitteilungen Serie A.     

Stokes' problem for a vertical infinite plate with variable temperature

An exact analysis of Stokes' problem for an infinite vertical plate, whose temperature varies linearly with time, has been presented. It is observed that the velocity near the plate increases with the timet, and the Grashof numberGr. The skin-friction has been found to vary ast ^7/2 and the Nusselt number varies as or whereP is the Prandtl number.