Reanalysis of two eclipsing binaries: <Emphasis Type="Italic">EE</Emphasis> <Emphasis Type="Italic">Aqr</Emphasis> and <Emphasis Type="Italic">Z</Emphasis> <Emphasis Type="Italic">Vul</Emphasis>

We study the radial-velocity and light curves of the two eclipsing binaries EE Aqr and Z Vul. Using the latest version of the Wilson and Van Hamme (Computing Binary Star Observables, 2003) model, absolute parameters for the systems are determined. We find that EE Aqr and Z Vul are near-contact and semi-detached systems, respectively. The primary component of EE Aqr fills about 96% of its ‘Roche lobe’, while its secondary one appears close to completely filling this limiting volume. In a similar way, we find fill-out proportions of about 72 and 100% of these volumes for the primary and secondary components of Z Vul respectively. We compare our results with those of previous authors.     

Quintessence cosmology with a traversable wormhole,massive decaying gravitons and with varying <Emphasis Type="Italic">G</Emphasis> and <Emphasis Type="Italic">Λ</Emphasis>

In this work, we explore many cosmological implications of a four-dimensional cosmology dominated by quintessence with a static traversable wormhole, spatio-temporal varying G and by taking into account a decaying cosmological constant and a decaying graviton mass by means of an additional bimetric tensor in Einstein’s field equations proposed by Visser in 1998.     

Study of the non-stationarity of the atmosphere of <Emphasis Type="Italic">κ</Emphasis> Cas. Ii. Variability of the H<Emphasis Type="Italic">γ</Emphasis>, H<Emphasis Type="Italic">β</Emphasis>, and H<Emphasis Type="Italic">α</Emphasis> wind-line profiles

We study the variability of the Hγ, Hβ, and Hα line profiles in the spectrum of the supergiant κ Cas. The variability pattern proved to be the same for all the lines considered: their profiles are superimposed by blueshifted, central, and redshifted emission. For Hγ the positions of the emissions coincide with the positions of the corresponding emissions for He I λλ 5876, 6678 Å lines, and are equal to about ?135 ± 30.0 km s^?1, ?20 ± 20 kms^?1, and 135 ± 30.0 kms^?1, respectively, whereas the three emissions in the Hβ profiles are fixed at about ?170.0 ± 70.0 kms^?1, 20 ± 30 kms^?1, and 170.0 ± 70.0 km s^?1, respectively. The positions of the blueshifted and central emissions for Hα are the same as for Hβ, with additional blueshifted emission at ?135.0 ± 30.0 kms^?1, whereas no traces of emission can be seen in the red wing of the line. These emissions show up more conspicuously in wind lines, however, their traces can be seen in all photospheric lines. When passing from wind lines to photospheric lines the intensity of superimposed emission components decreases and the same is true for the absolute values of their positions in line wings expressed in terms of radial velocities. The V/R variations of the lines studied found in the spectrum of κ Cas and the variability of the Hα emission indicate that the star is a supergiant showing Be phenomenon.     

Determination of the combination of cosmological parameters Ω<Subscript><Emphasis Type="Italic">m</Emphasis></Subscript><Superscript><Emphasis Type="Italic">α</Emphasis></Superscript><Emphasis Type="Italic">σ</Emphasis><Subscript>8</Subscript>

We have obtained new constraints on the cosmological parameters Ω _m and σ ₈ from the peculiar velocities of flat edge-on spiral galaxies from the RFGC catalog. Based on these results presented graphically, we have found the quantitative condition (Ω _m /0.3)^0.37 σ ₈ = 0.92 ± 0.05. The estimates of Ω _m and σ ₈, along with their combinations Ω _m ^α σ ₈ for various α, are compared with the estimates by other authors.     

Families <Emphasis Type="Italic">c</Emphasis> and <Emphasis Type="Italic">i</Emphasis> of periodic solutions of the restricted problem for μ = 5 × 10<Superscript>−5</Superscript>

We consider the circular planar restricted three-body problem with the mass parameter μ = 5 × 10^?5. Two families of periodic solutions are calculated: family c, starting from the collinear fixed point L ₁, and the initial part of familyi, which begins by direct circular orbits of an infinitely small radius around the body of bigger mass. The calculated families are very close to the generating ones, which we described earlier. In particular, the existence of the predicted zigzag structure of characteristics of family iis verified. New properties of the planar and vertical traces are discovered.     

Some expressions of gravity without the big ‘<Emphasis Type="Italic">G</Emphasis>’

This letter presents expressions for: Newton’s law of universal gravitation, Milgrom’s expression of Modified Newtonian Dynamics [MOND] for the velocity of stars at the out-skirts of spiral-galaxies, and some new relations between mass and radius of: globular-clusters, spiral-galaxies, and the galactic-clusters without any need for the big G. These expressions suggest that the strength of gravity and velocities of stars at the out-skirts of spiral-galaxies would be different if the total-mass and radius of the universe were different.     

Nonstationarity of the atmosphere of <Emphasis Type="Italic">α</Emphasis> Cyg: II. Variability of the ion and H<Emphasis Type="Italic">β</Emphasis> line profiles

We report an efficient method for analyzing the radial-velocity and line-profile variability. We show that a detailed analysis of the variations of line profiles and velocity field in the stellar atmosphere requires the radial velocities to be measured separately for the blue and red halves of the absorption lines at different levels of their residual intensity. We applied this method to 120 CCD spectra taken in 1998–99 with the coude echelle spectrograph attached to the 2-m telescope of Shemakha Astronomical Observatory of National Academy of Sciences of Azerbaijan and analyzed the variations of the radial velocities and profiles of ion and Hβ lines in the spectrum of α Cyg. In the case of ion lines both halves of the absorption profile exhibit synchronous radial-velocity variations at all levels of line intensity. In the case of the Hβ line, which forms in the layers where stellar wind originates, the pattern of radial-velocity variations differs for the blue and red halves of the absorption profile. The variability pattern is the same at all levels in the red half of the profile, the blue half of the profile exhibits different variability patterns at different levels of residual line intensity. Identification and analysis of such variations allows us to study the nature of stellar-wind variability in the region of wind formation.The spectrum of α Cyg showed no line-profile or radial-velocity variations for six days in both halves of the absorption contour at all levels of line intensity. The star was in the quiescent phase.     

Sensitivity of Selected Ba <Emphasis Type="SmallCaps">ii</Emphasis>, Fe <Emphasis Type="SmallCaps">i</Emphasis>, Fe <Emphasis Type="SmallCaps">ii</Emphasis>, and Cr <Emphasis Type="SmallCaps">i</Emphasis> Spectral Lines to Velocity in Quiet Solar Atmosphere

We examine the sensitivity of selected Ba?ii, Fe?i, Fe?ii, and Cr?i spectral lines to changes of the line-of-sight velocity by sharpness of their line profiles and response functions to line-of-sight velocity evaluated by the 1-D model of the quiet solar atmosphere in the LTE approximation. The set of selected lines includes the Ba?ii 4554 Å line, generally considered to be an excellent Doppler mapper. Our findings confirm earlier results showing that the sensitivity increases not only with wavelength, as anticipated from the Doppler relation, but mainly with the sharpness of line profiles given by the ratio of their depths and widths. The line Fe?i 5247 Å is the most sensitive in our set, whereas the Fe?i and Fe?ii infrared lines show very low sensitivity because of their large thermal widths. The line Ba?ii 4554 Å shows only moderate sensitivity due to its large width, given by a broad hyperfine structure and isotopic split. For the first time we identify a very promising and so far unknown Doppler mapper of the solar photosphere and low chromosphere, which is the line Ba?ii 6497 Å. Its sensitivity is comparable with the sensitivity of Fe?i 5247 Å and clearly surpasses the sensitivity of Ba?ii 4554 Å. The line Ba?ii 6497 Å offers many advantages, making it a highly recommendable choice for future studies of line-of-sight velocities in the photosphere and low chromosphere.     

The Na <Emphasis Type="SmallCaps">i</Emphasis> and Sr <Emphasis Type="SmallCaps">ii</Emphasis> Resonance Lines in Solar Prominences

We estimate the electron density, \(n_{\mathrm{e}}\), and its spatial variation in quiescent prominences from the observed emission ratio of the resonance lines Na?i?5890 Å (D₂) and Sr?ii?4078 Å. For a bright prominence (\(\tau_{\alpha}\approx25\)) we obtain a mean \(n_{\mathrm{e}}\approx2\times10^{10}~\mbox{cm}^{-3}\); for a faint one (\(\tau _{\alpha }\approx4\)) \(n_{\mathrm{e}}\approx4\times10^{10}~\mbox{cm}^{-3}\) on two consecutive days with moderate internal fluctuation and no systematic variation with height above the solar limb. The thermal and non-thermal contributions to the line broadening, \(T_{\mathrm{kin}}\) and \(V_{\mathrm{nth}}\), required to deduce \(n_{\mathrm{e}}\) from the emission ratio Na?i/Sr?ii cannot be unambiguously determined from observed widths of lines from atoms of different mass. The reduced widths, \(\Delta\lambda_{\mathrm{D}}/\lambda_{0}\), of Sr?ii?4078 Å show an excess over those from Na?D₂ and \(\mbox{H}\delta\,4101\) Å, assuming the same \(T_{\mathrm{kin}}\) and \(V_{\mathrm{nth}}\). We attribute this excess broadening to higher non-thermal broadening induced by interaction of ions with the prominence magnetic field. This is suggested by the finding of higher macro-shifts of Sr?ii?4078 Å as compared to those from Na?D₂.     

Family <Emphasis Type="Italic">h</Emphasis> of periodic solutions of the restricted problem for big μ

The results of the computation of the family h of symmetric periodic solutions of the circular planar restricted three-body problem for μ = 0.3, 0.4, and 0.5 are presented. This family begins with retrograde circular orbits around a massive body. Associated with each value of μ are the table of critical orbits, the orbit pictures, the graphs of characteristics of the family in four coordinate systems, and the graphs of the period and traces (planar and vertical). Regularities on the family and its evolution as μ increased were observed.     

Family <Emphasis Type="Italic">h</Emphasis> of periodic solutions of the restricted problem for small μ

The results of the calculation of the family h of symmetric periodic solutions of the planar restricted three-body problem for four values of μ = 0, 10^?3, 0.1, and 0.2 are presented. This family begins with retrograde circular orbits around the body of bigger mass. Associated with each value of μ are the table of critical orbits, the orbit pictures, graphs of the characteristics of the family in four coordinate systems, and graphs of the period and of traces (planar and vertical). Regularities on the family and its connection to the generating family are observed.     

Relative Contribution of the Hydrogen 2<Emphasis Type="Italic">s</Emphasis> Two-Photon Decay and Lyman-<Emphasis Type="Italic">α</Emphasis> Escape Channels during the Epoch of Cosmological Recombination

We discuss the evolution of the ratio in number of recombinations due to 2s two photon escape and due to the escape of Lyman-α photons from the resonance during the epoch of cosmological recombination, within the width of the last scattering surface and near its boundaries. We discuss how this ratio evolves in time, and how it defines the profile of the Lyman-α line in the spectrum of CMB. One of the key reasons for explaining its time dependence is the strong overpopulation of the 2p level relative to the 2s level at redshifts z ? 750.     

Orbit Orientation of the Planet in <Emphasis Type="Italic">τ</Emphasis> Boo (HD 120136)

We determined the rotation period and the parameters of the global magnetic field of τ Boo. This allowed us to estimate the inclination of the rotational axis of the star to the line of sight, as well as to obtain estimates of the inclination of the planet’s orbital plane to the stellar equator.     

The <Emphasis Type="Italic">r</Emphasis>-Process in the region of transuranium elements and the contribution of fission products to the nucleosynthesis of nuclei with <Emphasis Type="Italic">A</Emphasis> ≤ 130

We discuss the influence of nuclear masses and mass distributions of fission products on the formation of heavy elements at the final stages of the r-process recycled through fission on long duration timescales. The fission recycling is of great importance in an environment with a high density of free neutrons (e.g., in neutron star merger scenarios), when the r-process duration is long enough for most of the seed nuclei to be transformed into actinoids. The fission products of transuranium elements are again drawn into the r-process to produce the abundance curve beyond the iron peak. In this case, to explain the abundances of the A ～ 130 peak elements, not only the nuclear masses, fission barriers, and reaction rates, but also the fission product mass distribution must be predicted. Our r-process calculations using new nuclear masses and fission barriers and reaction rates based on them have shown that the simple two-fission-fragment model used previously in r-process calculations cannot describe adequately the position of the second peak in the observed abundance curve. We show that agreement between calculations and observations can be achieved only when we properly consider the mass distribution of fission products by taking into account the emission of instantaneous fission neutrons.     

Statistics of interacting galaxies at <Emphasis Type="Italic">z</Emphasis> ∼ 0.7

We present the results of our analysis of the frequencies of galaxies with tidal tails and M51-type galaxies in several deep fields of the Hubble Space Telescope (HDF-N, HDF-S, HUDF, GOODS, GEMS). In total, we have found about seven hundred interacting galaxies at redshifts z ≤ 1.5 in these fields. At z ≤ 0.7, the observed space densities of galaxies with tidal structures and M51-type galaxies have been found to increase as ∝(1 + z) ^m , where m ≈ 2.6. According to our estimates, over the last 6–7 Gyr, i.e., at z ≤ 0.7, about a third of the galaxies with M(B) ≤ −18 ^m must have undergone strong gravitational perturbations and mergers and ∼1/10−1/5 of the galaxies have swallowed relatively low-mass nearby satellites typical of M51-type galaxies. The possible decrease in the time scale on which a distant galaxy appears peculiar with growing z can increase considerably the estimated rate of mergers.     

Polarization of the H<Emphasis Type="Italic">α</Emphasis> emission and proton isotropization in solar flares

Isotropization mechanisms for a beam of low-energy (10–100 keV) protons in the Hα formation region are considered. An increase in the magnetic field strength is shown to have no significant effect on the pitch-angle distribution of the accelerated particles in the solar chromosphere. The excitation of small-scale Alfvén waves by protons can lead to their effective scattering. The results obtained are used to interpret peculiarities of the impact polarization of the Hα emission.     

Lifetimes of High-Degree <Emphasis Type="Italic">p</Emphasis> Modes in the Quiet and Active Sun

We study variations of the lifetimes of high-ℓ solar p modes in the quiet and active Sun with the solar activity cycle. The lifetimes in the degree range ℓ=300 – 600 and ν=2.5 – 4.5 mHz were computed from SOHO/MDI data in an area including active regions and quiet Sun using the time – distance technique. We applied our analysis to the data in four different phases of solar activity: 1996 (at minimum), 1998 (rising phase), 2000 (at maximum), and 2003 (declining phase). The results from the area with active regions show that the lifetime decreases as activity increases. The maximal lifetime variations are between solar minimum in 1996 and maximum in 2000; the relative variation averaged over all ℓ values and frequencies is a decrease of about 13%. The lifetime reductions relative to 1996 are about 7% in 1998 and about 10% in 2003. The lifetime computed in the quiet region still decreases with solar activity, although the decrease is smaller. On average, relative to 1996, the lifetime decrease is about 4% in 1998, 10% in 2000, and 8% in 2003. Thus, measured lifetime increases when regions of high magnetic activity are avoided. Moreover, the lifetime computed in quiet regions also shows variations with the activity cycle.     

Comparison of some characteristics of comets 1P/Halley and 67P/Churyumov–Gerasimenko from the <Emphasis Type="Italic">Vega</Emphasis> and <Emphasis Type="Italic">Rosetta</Emphasis> mission data

On March 6 and 9, 1986, for the first time in the history of science, the Russian spacecraft Vega-1 and -2 approached the nucleus of comet 1P/Halley and flew by at a small distance. A while later, on March 14, 1986, the Giotto spacecraft (European Space Agency (ESA)) followed them. Together with the Japanese spacecraft Suisei (Japan Aerospace Exploration Agency (JAXA)), they obtained spaceborne investigations of cometary nuclei. Direct studies of cometary bodies that bear traces of the Solar System formation were continued in the next missions to comets. Starting from 2014 and up to 2016 September, the Rosetta spacecraft (ESA), being in a low orbit around the nucleus of comet 67P/Churyumov–Gerasimenko, has performed extremely sophisticated investigations of this comet. Here, we compare some results of these missions. The paper is based on the reports presented at the memorial conference dedicated to the 30th anniversary of the Vega mission, which took place at the Space Research Institute of the Russian Academy of Sciences in March, 2016, and does not pretend to comprehensively cover the problems of cometary physics.     

Studying the influence of turbulent mixing on thermonuclear burning regimes during X-ray bursts of neutron stars using the <Emphasis Type="Italic">K</Emphasis><Subscript><Emphasis Type="Italic">ε</Emphasis></Subscript> model

We study the influence of turbulent mixing on the development of thermonuclear flashes in the surface layers of neutron stars. A simple K _ε model that includes various physical processes is used to describe the turbulent processes. In contrast to the widespread mixing-length theory, the K _ε model does not require using additional dimensional parameters, traces the development of turbulence in dynamics, describes the various turbulence development scenarios (gravitational and shear instabilities, convection, semiconvection, etc.) in a unified way, and can be used in multidimensional numerical simulations. Empirical constants of the model are chosen on the basis of experimental data and direct numerical simulations of typical processes. We have used the Era and Tigr-3T software packages to numerically simulate thermonuclear flashes in the accretion-renewable atmospheres of neutron stars. Turbulence is shown to accelerate significantly the transport of released energy to the stellar surface. Mixing equalizes the concentrations of matter components throughout the burning layer and increases the amount of matter involved in the thermonuclear burning during a flash.     

Some Robertson-Walker models with time dependent <Emphasis Type="Italic">G</Emphasis> and Λ

Einstein field equations with variable gravitational and cosmological constants are considered in the presence of perfect fluid for Robertson-Walker universe by assuming the cosmological term proportional to the Hubble parameter. This variation law for vacuum density has recently been proposed by Schützhold on the basis of quantum field estimations in the curved and expanding background. The cosmological term tends asymptotically to a genuine cosmological constant and the model tends to a deSitter universe. We obtain that the present universe is accelerating with a large fraction of cosmological density in the form of cosmological term.