Three-colour photometry of TW Cas

Photoelectric elements of the system TW Cas have been determined inU, B andV filters. A refined period of 1 _. ^d 428 324 77 has been given though no change in period is noticed. Spectroscopic elements given by Struve have been used to get the absolute elements. The system is found to be a detached one.     

Three-colour photometry of the eclipsing binary EI Cephei

The photoelectric elements of the system EI Cephei have been determined inU, B, V colours. The absolute dimensions have been determined and some evolutionary aspects have been discussed. A modified period of 8^d.439334 has been obtained. The system is a detached one.     

A galactic model with a pulsating active nucleus

The accumulation and distribution of rare-light elements in the Galaxy is investigated according to a model of the galaxy at which center there exists a pulsating active nucleus with decreasing activity with time. The abundances of rare-light elements rapidly decrease with approaching to the galactic center whereas the most abundant region of these elements is the annular region of the radial distance ofr=8～14 kpc from the galactic center. In the inner region ofr?8 kpc the abundances of these elements have varied by two to three orders of magnitude from the early days of the galactic history till now, but inr?8 kpc they have been almost constant within a factor of 2. It has become clear that if the nuclides D,³He,⁷Li,¹⁰B and¹¹B have been produced mainly by the shock process taking place in the outer envelope of type-II supernova, they must have been created by the mass fractions of the supernova of some 2.7×10^?3, 1.7×10^?4, 6.9×10^?8, 1.7×10^?7 and 7.9×10^?7, respectively, to account for the solar system abundances.     

A limit for gravitational collapse

Earlier, under certain simplifying assumptions, on the basis of the General Theory of Relativity, it has been concluded by many authors that when the radius of a gravitationally collapsing spherical object of massM reaches the critical value of the Scharzschild radiusR _s=2GM/c ², then, in a co-moving frame, the object collapses catastrophically to a point. However, in drawing this conclusion due consideration has not been given to the nuclear forces between the nucleons. In particular, the very strong ‘hard-core’ repulsive interaction between the nucleons which has the range ～0.4×10^?13 cm has been totally ignored. On taking into account this ‘hard-core’ repulsive interaction, it is found that no spherical object of massM g can collapse to a volume of radius smaller thanR _min=(1.68×10^?6)M ^1/3 cm or to a density larger than ρ_max=5.0 × 10¹⁶ g cm^?3. It has also been pointed out that objects of mass smaller thanM _c～1.21×10³³ g can not cross the Schwarzschild barrier and gravitationally collapse. The only course left to the objects of mass less thanM _cis to reach the equilibrium as either a white dwarf or a neutron star.     

Kinematic control of the inertiality of the system of Tycho-2 and UCAC2 stellar proper motions

Based on the Ogorodnikov-Milne model, we analyze the proper motions of Tycho-2 and UCAC2 stars. We have established that the model component that describes the rotation of all stars under consideration around the Galactic y axis differs significantly from zero at various magnitudes. We interpret this rotation found using the most distant stars as a residual rotation of the ICRS/Tycho-2 system relative to the inertial reference frame. For the most distant (d≈900 pc) Tycho-2 and UCAC2 stars, the mean rotation around the Galactic y axis has been found to be M ₁₃ ^? =?0.37±0.04 mas yr^?1. The proper motions of UCAC2 stars with magnitudes in the range 12–15^m are shown to be distorted appreciably by the magnitude equation in μ_α cos δ, which has the strongest effect for northern-sky stars with a coefficient of ?0.60±0.05 mas yr^?1 mag^?1. We have detected no significant effect of the magnitude equation in the proper motions of UCAC2 stars brighter than ≈11^m.     

Studies of microparticle impact phenomena leading to the development of a highly sensitive micrometeoroid detector

A highly sensitive device has been developed for the detection of micrometeoroids with masses extending down to and below the expected classical solar radiation pressure limit. This limit occurs at a mass of about 10⁻¹⁶ kg for a particle density of 3 × 10³ kg m⁻³. The detector operates on the principle that charge (Q) is released when a hypervelocity microparticle impacts on a solid surface. This process has previously been investigated at particle velocities (ν) greater than 1 km sec⁻¹ and the empirical relationship Q = Km^αν^β obtained where m is the particle mass and K, α and β are constants. In the present study the validity of this relationship has been demonstrated for iron particles with masses from 10⁻¹⁶ to 10⁻¹³ kg in the velocity range 0.05–1.4 km sec⁻¹ impacting on a molybdenum target. A value of α ≈ 1 is indicated and a value of β of 3.2 ± 0.4 has been obtained.     

Minimum on the light curve of the classical symbiotic star AS 338 in 1999

We present our UBVRI photometry and spectroscopy of AS 338 performed in 1999–2000. Another eclipse of the hot component in this symbiotic binary system, the deepest one ever observed, occurred in September 1999. The U brightness declined by ～2^m, the Hβflux decreased by a factor of ～2.3, and the [O III]γ5007 flux did not change. The hot component is eclipsed at orbital phases ?≈0.045–0.057. The U-B color index begins to appreciably fluctuate during an eclipse of the hot component and its circumstellar envelope. About 100 days after a strong outburst of 1995, the mean UBV brightness of AS 338 declined linearly in the ensuing five years at the same rate in all bands (ΔU/Δt≈10^?3 mag/day). The brightness of the outer, uneclipsed parts of the circumstellar envelope also decreased, which is attributable to a reduction in the luminosity of the hot component against the rise in its temperature. The appearance of He II lines has not yet been recorded, though the optical brightness of AS 338 has already dropped by ～2^m after the outburst.     

A new period and period changes in VZ Hydrae

A new period (P=2 _. ^d 9042997) of the eclipsing binary system VZ Hydrae has been given, which is based on all the available times of minima. The period based on the photoelectric epochs has also been presented. The O?C diagram and detailed period study of VZ Hya have been presented for the first time, and the period changes have been estimated in different portions of the O?C diagram. Significant period changes do not appear to have occurred in VZ Hya, however, the O?C diagram suggests that the period of the system shows a slow tendency to increase. Period changes of 10^?5 d (?) to 10^?7 d have occurred around the years 1933, 1971, and 1975. All four period changes are noted in the time-interval 1918 to 1978. Upward treands appear stronger than the declining trends. Secondary minima show larger fluctuations than the primary minima. The fluctuations of the O?C values around the zero-line of VZ Hya demands notice for searching out the cause of period variations such as the presence of a third body.     

Ultraviolet solar identifications based on extended absorption series observed in the laboratory spectrum of Sii

The absorption spectrum of Sii in the wavelength region 1500–1900 Å has been photographed at high resolution. The silicon vapour was produced in a 122 cm long King furnace at 1800–2300°C. Forty-two Rydberg series have been observed from the ground state terms 3p ^{2 3} P and¹ D to terms associated with the 3pns and 3pnd configurations. All of the series from these configurations withJ<4 have been extended with the 3pnd ³ D ₃ ^o levels reachingn=56. Numerous perturbations have been observed. This laboratory work has provided the basis for extending the identification of silicon lines in the solar spectrum. Nearly all lines found in the laboratory spectrum are also found in rocket spectrograms of the solar chromosphere. More than 300 lines have been attributed to Sii. The excellent correlation between laboratory and solar Sii lines will be illustrated.     

Cepheid kinematics and the Galactic warp

The space velocities of 200 long-period (P>5 days) classical Cepheids with known proper motions and line-of-sight velocities whose distances were estimated from the period-luminosity relation have been analyzed. The linear Ogorodnikov-Milne model has been applied, with the Galactic rotation having been excluded from the observed velocities in advance. Two significant gradients have been found in the Cepheid velocities, ?W/?Y = ?2.1 ± 0.7 km s^?1 kpc^?1 and ?V/?Z = 27 ± 10 km s^?1 kpc^?1. In such a case, the angular velocity of solid-body rotation around the Galactic X axis directed to the Galactic center is ?15 ± 5 km s^?1 kpc^?1.     

Space erosion of meteorites and the secular variation of cosmic rays (over 109 years)

The space erosion of stony meteorites has been determined to be 650μm 10⁶y^?1, while that of iron meteorites has been determined to be 22 μm 10⁶y^?1. The erosion rates are based on flux and size distributions of small particles in the solar system, meteoroid orbitals and the relation, determined by laboratory experiments, between excavated volume due to a collision and the size and velocity of the impacting small particle. Neither multiple collision or space erosion can explain the difference in cosmic ray exposure ages based on ${}^{40}\text{K}$ and those based on ${}^{36}\text{Cl}\text{,}{}^{39}\text{Ar and}{}^{10}\text{Be}$. It is concluded that there is a long term cosmic ray variation.     

A pseudo third order symplectic integrator

The symplectic integrator has been regarded as one of the optimal tools for research on qualitative secular evolution of Hamiltonian systems in solar system dynamics. An integrable and separate Hamiltonian system H = H₀ + Σ_i=1^N ε_iH_i (ε_i ≪ 1) forms a pseudo third order symplectic integrator, whose accuracy is approximately equal to that of the first order corrector of the Wisdom-Holman second order symplectic integrator or that of the Forest-Ruth fourth order symplectic integrator. In addition, the symplectic algorithm with force gradients is also suited to the treatment of the Hamiltonian system H = H₀(q,p) + εH₁(q), with accuracy better than that of the original symplectic integrator but not superior to that of the corresponding pseudo higher order symplectic integrator.     

Testing quantised inertia on galactic scales

Galaxies and galaxy clusters have rotational velocities (v) apparently too fast to allow them to be gravitationally bound by their visible matter (M). This has been attributed to the presence of invisible (dark) matter, but so far this has not been directly detected. Here, it is shown that a new model that modifies inertial mass by assuming it is caused by Unruh radiation, which is subject to a Hubble-scale (Θ) Casimir effect predicts the rotational velocity to be: v ⁴=2GMc ²/Θ (the Tully-Fisher relation) where G is the gravitational constant, M is the baryonic mass and c is the speed of light. The model predicts the outer rotational velocity of dwarf and disk galaxies, and galaxy clusters, within error bars, without dark matter or adjustable parameters, and makes a prediction that local accelerations should remain above 2c ²/Θ at a galaxy’s edge.     

Circumstellar Na I and Ca II absorption lines of type Ia supernovae in the symbiotic scenario

The formation of circumstellar Na I and Ca II resonance absorption lines in a type Ia supernova is studied in the case where the supernova explodes in a binary system with a red giant. The model suggests a spherically symmetric wind and takes into account the nonstationary ionization and heating of the wind by X rays from the shock wave and by gamma rays from radioactive ⁵⁶Ni decay. For wind densities typical of a red giant, the expected optical depth of the wind in Na I lines is shown to be too small (τ < 10^?3) for their detection. Under the same conditions, the optical depth of the predicted Ca II 3934 Å absorption line is sufficient for its detection (τ > 0.1). It is concluded that the Na I and Ca II absorption lines detected in SN 2006X could not be formed in the red giant wind and are most likely related to clouds at distances exceeding the dust evaporation radius (r > 10¹⁷ cm). An upper limit for the rate of mass loss through a stationary wind with velocity u has been obtained from the absence of Ca II absorption lines in SN 2006X unrelated to the similar Na I components: ? < 10^?8 (u/10 km s^?1) M _⊙ yr^?1.     

A new class of Inhomogeneous string cosmological models in general relativity

A new class of solutions of Einstein field equations has been investigated for inhomogeneous cylindrically symmetric space-time with string source. To get the deterministic solution, it has been assumed that the expansion (θ) in the model is proportional to the eigen value σ ¹  ₁ of the shear tensor σ ⁱ    _j . Certain physical and geometric properties of the models are also discussed.     

The solar wind-magnetosphere energy coupling and magnetospheric disturbances

The recent finding of the solar wind-magnetosphere energy coupling function ε has advanced significantly our understanding of magnetospheric disturbances. It is shown that the magnetosphere-ionosphere coupling system responds somewhat differently to three different input energy flux levels of ε. As ε increases from < 10¹⁷ erg s^?1 to > 0¹⁹ erg s^?1, typical responses of the magnetosphere-ionosphere coupling system are:ε < 10¹⁷ erg s^?1: an enhancement of the S_q^p, etc,ε ≈ 10¹⁸ erg s^?1: substorm onset,10¹⁸ erg s^?1 < ε < 10¹⁹ erg s^?1f: a typical substorm,ε >10¹⁹ erg s^?1: an abnormal growth of the ring current belt, resulting in a magnetospheric storm.It is stressed that the magnetospheric substorm results as a direct response of the magnetosphere to a rise and fall of ε above ≈ 10¹⁸ erg s^?1, so that it is not caused by a sudden conversion of magnetic energy accumulated prior to substorm onset. The variety of the development of the main phase of geomagnetic storms is also primarily controlled by ε.     

A rare reflection effect eclipsing sdB+dM binary: 2M 1533+3759

In this paper, we report a rare reflection effect eclipsing sdB+dM binary, 2M?1533+3759. It is the seventh eclipsing sdB+dM binary that has been discovered to date. This system has an orbital period of 0.16177042 day and a velocity semi-amplitude of 71.1 km?s^?1. Using a grid of zero-metallicity NLTE model atmospheres, we derived T _eff=29250 K, log?g=5.58 and [He/H]=?2.37 from spectra taken near the reflection effection minimum. Lightcurve modeling resulted in a system mass ratio of 0.301 and an orbital inclination angle of 86.6°. The derived primary mass for 2M?1533+3759, 0.376±0.055 M _⊙, is significantly lower than the canonical mass (0.48 M _⊙) found for most previously investigated sdB stars. This implies an initial progenitor mass >1.8 M _⊙, at least a main sequence A star and perhaps even one massive enough to undergo non-degenerate helium ignition.     

Estimation of the solar galactocentric distance and galactic rotation velocity from near-solar-circle objects

We have tested the method of determining the solar Galactocentric distance R ₀ and Galactic rotation velocity V ₀ modified by Sofue et al. using near-solar-circle objects. The motion of objects relative to the local standard of rest has been properly taken into account. We show that when such young objects as star-forming regions or Cepheids are analyzed, allowance for the perturbations produced by the Galactic spiral density wave improves the statistical significance of the estimates. The estimate of R ₀ = 7.25 ± 0.32 kpc has been obtained from 19 star-forming regions. The following estimates have been obtained from a sample of 14 Cepheids (with pulsation periods P > 5 ^d ): R ₀ = 7.66 ± 0.36 kpc and V ₀ = 267 ± 17 km s^?1. We consider the influence of the adopted Oort constant A and the character of stellar proper motions (Hipparcos or UCAC4). The following estimates have been obtained from a sample of 18 Cepheids with stellar proper motions from the UCAC4 catalog: R ₀ = 7.64 ± 0.32 kpc and V ₀ = 217 ± 11 km s^?1.     

Computedn=2 level populations in helium-like ions from Cv to Nixxvii

The population densities of all levels with principal quantum numbern=2 in a number of helium-like ions with nuclear charge numberZ, in the range 6 to 28 have been evaluated as a function of various parameters, i.e., electron temperature,T _e, electron density,N _e, radiation temperature,T _r, dilution factor,W, and of the state of ionization. The spectral line fluxes from all possible radiative transitions from these levels have been calculated for an optically thin plasma. The effects of cascades following collisional excitation of higher levels or radiative and dielectronic recombination have been computed in detail. Innershell ionization of the lithium-like ion to form the helium-like ion in a 2³ S or 2¹ S state has been considered. It can have a strong influence on the forbidden line intensity in a non-equilibrium plasma. Collisional and radiative coupling of levels of the same multiplicity (e.g. 2³ S ₁ and 2³ P _2,1,0) have been considered as a function ofT _e, N_e orT _r, W, respectively. The computations were performed both for stationary and time-varying plasmas. In the latter case strong departures from a stationary ionization equilibrium can significantly alter the line fluxes. A few examples of the results are shown and discussed.     

Galactic rotation parameters from data on open star clusters

Currently available data on the field of velocities V _r , V _l , V _b for open star clusters are used to perform a kinematic analysis of various samples that differ by heliocentric distance, age, and membership in individual structures (the Orion, Carina-Sagittarius, and Perseus arms). Based on 375 clusters located within 5 kpc of the Sun with ages up to 1 Gyr, we have determined the Galactic rotation parameters ω ₀ = ?26.0 ± 0.3 km s^?1 kpc^?1, ω′₀ = 4.18 ± 0.17 km s^?1 kpc^?2, ω″₀ = ?0.45 ± 0.06 km s^?1 kpc^?3, the system contraction parameter K = ?2.4 ± 0.1 km s^?1 kpc^?1, and the parameters of the kinematic center R ₀ = 7.4 ± 0.3 kpc and l ₀ = 0° ± 1°. The Galactocentric distance R ₀ in the model used has been found to depend significantly on the sample age. Thus, for example, it is 9.5 ± 0.7 and 5.6 ± 0.3 kpc for the samples of young (≤50 Myr) and old (>50 Myr) clusters, respectively. Our study of the kinematics of young open star clusters in various spiral arms has shown that the kinematic parameters are similar to the parameters obtained from the entire sample for the Carina-Sagittarius and Perseus arms and differ significantly from them for the Orion arm. The contraction effect is shown to be typical of star clusters with various ages. It is most pronounced for clusters with a mean age of ≈100 Myr, with the contraction velocity being Kr = ?4.3 ± 1.0 km s^?1.