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1.
The first photoelectric light curve of the eclipsing binary system BW Aqr (F71V+F81V;P=6d.7;V=10 m .31), discovered by Miss Leavitt at the beginning of the century, was obtained. The photometric elements were detemined. The components of this system are considerably evolved stars: the age of the system is about 2×109 yr. It follows from the photometric data that the secondary component should have greater mass than the primary one The zero-age spectral classes of components were F2V and F1V. The system has an elliptical orbit with the eccentricitye=0.18. The angular rate of the apsidal motion (obs = 0.070 deg yr–1) and the corresponding value of the apsidal parameterk 2=0.0090 (the relativistic term included) were found. The derived valuek 2 exceeds by more than a factor of 2 the theoretical coefficient obtained from the modern theory of internal structure of stars with moderate masses .  相似文献   

2.
A comprehensive period study of the times of minima observed from 1881 to 1985 has been performed. Previous interpretations of the O–C diagram based on light-time effect are confirmed. The light-time orbit of U Oph has been revised using a differential corrections procedure. We get an eccentric orbit withe=0.22±0.06,P=38.7±0.2 yr, and a mass function . In addition, our analysis has revealed short-period apsidal motion (U/P=4515±75) in a slightly eccentric close orbit (e=0.0031±0.0003), allowing a reliable determination of the density concentration coefficient,k 2=0.0059±4. A comparison with stellar evolutionary models calculated by Jeffery (1984) yields the helium contentY=0.28±0.05 and an age of 3×107 yr for the components of U Oph.  相似文献   

3.
MulticolourWBVR photoelectric observations of the eclipsing binary V 451 Oph were carried out, and a highly accurate light curve was obtained. The angular velocity of the orbital rotation, =2.1 deg yr–1, and the apsidal motion constantk 2=0.0045 are given.  相似文献   

4.
If fluctuations in the density are neglected, the large-scale, axisymmetric azimuthal momentum equation for the solar convection zone (SCZ) contains only the velocity correlations and where u are the turbulent convective velocities and the brackets denote a large-scale average. The angular velocity, , and meridional motions are expanded in Legendre polynomials and in these expansions only the two leading terms are retained (for example, where is the polar angle). Per hemisphere, the meridional circulation is, in consequence, the superposition of two flows, characterized by one, and two cells in latitude respectively. Two equations can be derived from the azimuthal momentum equation. The first one expresses the conservation of angular momentum and essentially determines the stream function of the one-cell flow in terms of : the convective motions feed angular momentum to the inner regions of the SCZ and in the steady state a meridional flow must be present to remove this angular momentum. The second equation contains also the integral indicative of a transport of angular momentum towards the equator.With the help of a formalism developed earlier we evaluate, for solid body rotation, the velocity correlations and for several values of an arbitrary parameter, D, left unspecified by the theory. The most striking result of these calculations is the increase of with D. Next we calculate the turbulent viscosity coefficients defined by whereC ro 0 and C o 0 are the velocity correlations for solid body rotation. In these calculations it was assumed that 2 was a linear function of r. The arbitrary parameter D was chosen so that the meridional flow vanishes at the surface for the rotation laws specified below. The coefficients v ro i and v 0o i that allow for the calculation of C ro and C 0o for any specified rotation law (with the proviso that 2 be linear) are the turbulent viscosity coefficients. These coefficients comply well with intuitive expectations: v ro 1 and –v 0o 3 are the largest in each group, and v 0o 3 is negative.The equations for the meridional flow were first solved with 0 and 2 two linear functions of r ( 0 1 = – 2 × 10 –12 cm –1) and ( 2 1 = – 6 × 10 12 cm –1). The corresponding angular velocity increases slightly inwards at the poles and decreases at the equator in broad agreement with heliosismic observations. The computed meridional motions are far too large ( 150m s–1). Reasonable values for the meridional motions can only be obtained if o (and in consequence ), increase sharply with depth below the surface. The calculated meridional motion at the surface consists of a weak equatorward flow for gq < 29° and of a stronger poleward flow for > 29°.In the Sun, the Taylor-Proudman balance (the Coriolis force is balanced by the pressure gradient), must be altered to include the buoyancy force. The consequences of this modification are far reaching: is not required, now, to be constant along cylinders. Instead, the latitudinal dependence of the superadiabatic gradient is determined by the rotation law. For the above rotation laws, the corresponding latitudinal variations of the convective flux are of the order of 7% in the lower SCZ.  相似文献   

5.
Results of evolutionary calculations for a close binary system with a central helium burning He-star filling its Roche lobe and an accreting white dwarf are presented. Values for the mass of the components and the degree of central helium exhaustion before the filling of the Roche lobe are varied. It is shown that in such a system the mass accretion rate will remain for a long time (2–4) Ö 10–8 yr–1 ifq<1 (q=M He,2/M CO,1). The obtained results are discussed in connection with pre-supernova I phenomenon.  相似文献   

6.
A principally new, quantitative system of the classification of the spectra of planetary nebulae is proposed. Spectral class of excitation class of the nebulap is determined according to the relative intensities of emission lines (N 1+N 2) [OIII]/4686 HeII and (N 1+N 2) [OIII]/H (Table I, Figure 1). The excitation classes are obtained for 142 planetary nebulae of all classes—low (p=1–3), middle (p=4–8), and high (p=9–12+) (Tables II, III, and IV). An empirical relationship between excitation classp and mean radius of nebulae is discovered (Figure 2). This relationship as well as excitation classp, as an independend parameter, admit an evolutionary interpretation. It is shown that after reaching the highest class of excitationp=12+ the nebulae decrease their class of excitation with the further increases of sizes. The diagram of this relationship has two nearly-symmetric branches — rising and descending with the apogee onp=12+ (Figure 2).  相似文献   

7.
This paper points out the errors in the solutions of a research work by N. Nanousis under the same title published in this journal, volume 199, 1993. The correct solutions of the problem for the velocity field and the drag on the plate, by the Laplace transform technique, are presented. The results are discussed for two cases of an arbitrary time-dependent forcing effect. It is shown that the viscoelastic parameterk > 0 influences the velocity and introduces reverse flow. For a suddenly accelerated plate,k > 0 increases the velocity forz < and decreases it forz > . In the case of the ramp-type boundary condition,k > 0 tends to decrease the velocity.  相似文献   

8.
Two models for superluminal radio sources predict sharp lower bounds for the apparent velocities of separation. The light echo model predicts a minimum velocityv min=2c, and the dipole field model predictsv min=4.446c. Yahil (1979) has suggested that, if either of these models is correct, thenv min provides a standard velocity which can be used to determine the cosmological parametersH andq 0. This is accomplished by estimating a lower envelope for the proper motion vs redshift relation. Yahil also argued that the procedure could easily be generalized to include a nonzero cosmical constant . We derive the formulas relating the proper motion to the redshiftz in a Friedmann universe with a nonzero . We show that the determination of a lower envelope for a given sample of measured points yields an estimate of the angle of inclination i for each source in the sample. We formulate the estimation of the lower envelope as a constrained maximum likelihood problem with the constraints specified by the expected value of the largest order statistic for the estimated i . We solve this problem numerically using an off-the-shelf nonlinearly constrained nonlinear optimization program from the NAg library. Assuming =0, we apply the estimation procedure to a sample of 27 sources with measured values , using both the light echo and the dipole field models. The fits giveH=103 km s–1 Mpc–1 for the light echo model andH=46 km s–1 Mpc–1 for the dipole field model. In both cases the fits giveq 0=0.4, but the uncertainty in this result is too large to rule out the possibility thatq 0>0.5. When is allowed to be a free parameter, we obtainH=105 km s–1 Mpc–1 for the light echo model andH=47 km s–1 Mpc–1 for the dipole field model. In both cases the fits giveq 0=–1 and /H 0 2 =6.7, but no significance can be attached to these results because of the paucity of measured data at hight redshifts. For all of the fits, we compute the corresponding estimates of the i and compare the cumulative distribution of these values with that expected from a sample of randomly oriented sources. In all cases we find a large excess of sources at low-inclination angles (high apparent velocities). The expected selection effect would produce such an excess, but the excess is large enough to suggest a strong contamination of the sample by relativistic beam sources which would only be seen at low inclination angles.Applied Research Corporation  相似文献   

9.
For Jupiter, an overall density model of the form= 0(1–x n ), withn1/3 and , is consistent with information presently at hand; for Saturn, however, such a density law would lead to unacceptably high densities in the vicinity of the centre. The limiting cases of the previous law are shown to ben=+, corresponding to a homogeneous sphere, andn=–3, corresponding to a particular central particle model, investigated by a number of astronomers over the last hundred years. Forn0, the central density becomes +. Another possible representation, valid both for Jupiter and Saturn, is the density law= 0(1–x) m ), with in the case of Jupiter, and in the case of Saturn. Graber's density law based on a maximum entropy principle leads to unacceptably high surface densities, both for Jupiter and Saturn. Finally, the paper investigates the problems involved in fitting two-layered parametrically simple density laws to theoretically derived much more elaborate models of the Jovian planets.  相似文献   

10.
Vibrational transition probabilities, namely Franck—Condon factors and -centroids have been evaluated by an approximate analytical method for the (A–X), (A–X), and (A–X) system of YO molecule. Morse potential energy curves forX 2+,A 22,A22, andA22, states of YO have been constructed using the latest spectroscopic data. The value of -centroids for the band have been found to decrease linearly with the corresponding wavelengths. We show results for two new transitions of (A–X) and (A–X) and five new bands of (A–X) of YO in the umbral spectrum of the Sun.  相似文献   

11.
The open star clusters M36, M38 and NGC 2477 were investigated by the strip method on charts of photographs taken with the Schmidt-Spiegel of the German Observatory Hoher List (M36/38) and the Curtis-Schmidt Telescope of the Cerro Tololo Interamerican Observatory (NGC 2477). The results are — Masses: 830, 2350, 4400 ; radii: 6.4, 10.0, 10.0 pc; central densities: 9.9, 15.3, 32.5 pc–3; density laws: Gaussian (M36), generalized law of Schuster withn=3.00, 2.79; mean velocities of the stars 0.74, 1.01, 1.38 km s–1.

Mitteilungen Serie A.  相似文献   

12.
The diffusion of charged particles in a stochastic magnetic field (strengthB) which is superimposed on a uniform magnetic fieldB 0 k is studied. A slab model of the stochastic magnetic field is used. Many particles were released into different realizations of the magnetic field and their subsequent displacements z in the direction of the uniform magnetic field numerically computed. The particle trajectories were calculated over periods of many particle scattering times. The ensemble average was then used to find the parallel diffusion coefficient . The simulations were performed for several types of stochastic magnetic fields and for a wide range of particle gyro-radius and the parameterB/B 0. The calculations have shown that the theory of charged particle diffusion is a good approximation even when the stochastic magnetic field is of the same strength as the uniform magnetic field.  相似文献   

13.
The distribution of pulsars in the wide range of observed luminosities has been obtained. It is shown that the function of luminosity (FL) within 3×1026L2×1030 erg s–1 conforms to the power law dN/dL–c 1 L –, where =1.76±0.06. ForL3×1026 erg s–1, FL changes its inclination and may be approximated as , where 1 = 0.7±0.2. On the basis of statistical selection, including all pulsars withL>3×1028 erg s–1, the distribution of pulsars has been investigated as a function of the distance to the centreR and galactic planeZ.The obtained laws of the radial andZ-distribution of pulsars and galactic supernova remnants and also the radial distribution of types I and II supernovae in the models Sb and Sc support the hypothesis of their origin from the objects of the flat subsystem of Population I. Since there are some arguments in favour of a possible connection between supernovae I and the objects of the intermediate component of the Galaxy, one cannot exclude the possibility of supernovae explosions at the end of the evolution of stars with masses of 1.5–2M . It is also shown that pulsars and supernovae are evidently objects that are connected genetically, and, within the limits of statistical error, they have a similar birth-rate.The empirical law of the evolution of a pulsar's luminosity as a function of its true age has been obtained, according to whichL=c 2 t –, wherec 2=(3.69±3.4)×1035, =1.32±0.11.  相似文献   

14.
Newtonian cosmology is developed with the assumption that the gravitational constantG diminishes with time. The functional form adopted forG(t), a modification of a suggestion of Dirac, isG=A(k+t) –1, wheret is the age of the Universe and a small constantk is inserted to avoid a singularity in the two-body problem. IfR is the scale factor, normalized to unity at an epoch time , the differential equation is then . Here 0 is the mean density at the epoch time. With the above form forG(t), the solution is reducible to quadratures.The scale factorR either increases indefinitely or has one and only one maximum. LetH 0 be the present value of Hubble's constant /R and 0c the minimum density for a maximum ofR, i.e., for closure of the Universe. The conditions for a maximum lead to a boundary curve of 0c versusH 0 and the numbers indicate strongly that thisG-variable Newtonian model corresponds to an open universe. An upward estimate of the age of the Universe from 1010 yr to five times such a value would still lead to the same conclusion.The present Newtonian cosmology appears to refute the statement, sometimes made, that the Dirac model forG necessarily leads to the conclusion that the age of the Universe is one-third the Hubble time. Appendix B treats this point, explaining that this incorrect conclusion arises from using all the assumptions in Dirac (1938). The present paper uses only Dirac's final result, viz,G(k+t)–1, superposing it on the differential equation .  相似文献   

15.
The integral balance method has been used to obtain an approximate analytical solution of a nonlinear boundary value problem which arises in the theory of diffusion with a concentration-dependent coefficient. It is the purpose of this paper to give an interpretation of the supposition of interface reactions which obey the law of kinetic mass action.Nomenclature C(Z,t) concentration - C 0 concentration at initial time - D diffusivity - D 0 diffusivity at initial time - F(t) a function of time - K 0 half-order reaction rate constant - k 1 first-order reaction rate constant - k 2 second-order reaction rate constante - L characteristic length - n parameter - t time - Z space variable Dimensionless variables and similarity criteria nondimensional half-order reaction rate constant - nondimensional first-order reaction rate constant - nondimensional second-order reaction rate constant - x=Z/L dimensionless space variable - F 0=D 0 t/L 2 Fourier number - g(F 0)=[F(t)–C 0]/C 0 a function of generalized time - (x, F 0)=[C(x,t)–C 0]/C 0 dimensionless concentration - <(F 0)> dimensionless average concentration  相似文献   

16.
The equation of state of the terrestrial material obtained from seismic data is adopted to construct three zone earth models under hypothesis of variable constant of gravityG as proposed by Dirac. Three hypotheses are investigated: variableG without creation, creation such thatm (mass) G –1, and multiplicative creation,mG –2. It is shown that, with the currently accepted value of the Hubble constant, , and for each hypothesis. On the multiplicative creation, the Earth radius would have been 5100 km, which is in agreement with estimate by some geophysicists.  相似文献   

17.
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.

Mitteilungen Serie A.  相似文献   

18.
Three groups of galactic mass models, each consisting of nine inhomogeneous spheroids of two kinds are described, according to three adopted values of the total density near the Sun: 0.10, 0.15 and 0.20 M pc–3. Approximately 20% of the total mass of each model is in the halo, constructed to adequately fit recent RR Lyrae star observations. It is shown that the maxima found in the RR Lyrae star densities towards the galactic axis (Plaut, 1970) should not be interpreted as being associated with the galactic nucleus, but as the result of the greater decrease in density with increasingz over the increase in density as the galactic axis is approached. Even at the low galactic latitude of 5° (l=0°), this effect causes a 0.5 kpc correction to the distance to the galactic centre. A basic model for kpc, km s–1, M pc–3 is first constructed, mainly to satisfy structural conditions near the sun and in the halo. An attempt to optimize the basic model is made by scaling it so as to retain constant density and angular velocity near the sun, and to best fit kinematic data, including the recent re-examination of the 21-cm data of Simonson and Mader (1972). No unknown matter is required in the models, in accordance with the results of Weistrop (1972b), and, as pointed out earlier (Innanen, 1966b) the faintM-stars must be in a highly flattened spheroid. The optimizing indicates that an adequate fit to kinematics can be achieved for km s–1. More detailed results are tabulated for a representative model for which . Two new galactic density functions are discussed in the Appendix.  相似文献   

19.
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.  相似文献   

20.
The emission spectrum of comet Skoritchenko–George (C/1989 VI), unusual in its information content, was obtained on February 26.7 UT, 1990, with the use of a TV scanner installed on the 6-m BTA reflector of the Special Astronomical Observatory of the Russian Academy of Sciences (SAO RAS) in Nizhni Arkhyz. Detailed identification of the emission lines of this comet was made. The observed spectrum contains 311 emission lines, including those of the molecules. Among others, the lines of the negative carbon C 2 - ion and the lines corresponding to the electron transition in the neutral CO molecule are discovered. The presence of a large number of lines of the neutral CO molecule (the Asundi bands and the triplet bands) in the visible region is one of the uncommon features of the emission spectrum of this comet. The triplet lines : 15–3, 13–2, 11–2, 9–1, 8–1, 7–1, 7–0, 5–0, 4–0; : 7–0, 6–0, 5–0; and a" : 11–1 (K = 3, 4); 16–4 (K= 0, 1, 2, 4); 9-0 (K= 0, 1, 2); 8–0 (K= 0) were identified for the first time. Prior to this work, the lines of CO in the visible range were observed only in the spectrum of comet C/1979 VI (Bradfield) in 1989.  相似文献   

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