Dynamical study of wide pairs of stars based on data from the WDS catalog

Using the method of apparent motion parameters, we have studied the relative motion of the components in 561 pairs of wide (ρ > 2″) and relatively nearby (Hipparcos parallaxes > 0.01″) visual double stars based on data from the WDS catalog. The minimum masses of the double stars have been calculated at given parallaxes. We have identified 358 optical pairs. For 11 stellar pairs, we have found the minimum mass to exceed the estimate corresponding to their spectral types and luminosities. This excess is 5–7 M _⊙ for two stars, ADS 7446 and 9701.     

Abundance analysis and searching for nonradial pulsations in the atmosphere of the chemically peculiar star HD 115708

We present the results of our abundance analysis for the magnetic chemically peculiar star HD 115708 based on high-resolution spectra. The atmospheric chemical composition of HD 115708 (T _eff = 7550 K) is shown to be typical of cool Ap stars with a significant ionization disequilibrium for the first and second rare earth ions, which is commonly observed in the atmospheres of pulsating Ap (roAp) stars. Our study of the vertical distribution of elements has shown that Mg, Ca, Cr, and Fe concentrate in deeper atmospheric layers, with their abundances decreasing sharply in the upper layers. The jumps in abundance are 1.5–3 orders of magnitude. Silicon is distributed in depth almost uniformly in the atmosphere of HD 115708. The derived empirical Cr and Fe distributions agree qualitatively with the results of diffusion calculations. Since the atmospheric chemical peculiarities in HD 115708 correspond to roAp stars, we have performed a spectroscopic monitoring to find nonradial pulsations. We have been able to determine only an upper limit for the amplitude of the possible radial velocity pulsations, ～100 m s^?1, due to the insufficient temporal resolution and instability of the main stellar spectrograph (MSS) of the 6-m telescope.     

Analysis of fundamental parameters for V477 Lyr

We analyze the photometric and spectroscopic observations of the young pre-cataclysmic variable (pre-CV) V477 Lyr. The masses of both binary components have been corrected by analyzing their radial velocity curves. We show that agreement between the theoretical and observed light curves of the object is possible for several sets of its physical parameters corresponding to the chosen temperature of the primary component. The final parameters of V477 Lyr have been established by comparing observational data with evolutionary tracks for planetary nebula nuclei. The derived effective temperature of the O subdwarf is higher than that estimated by analyzing the object’s ultraviolet spectra by more than 10000 K. This is in agreement with the analogous results obtained previously for the young pre-CVs V664 Cas and UU Sge. The secondary component of V477 Lyr has been proven to have a more than 25-fold luminosity excess compared to main-sequence stars of similar mass. Comparison of the physical parameters for the cool stars in young pre-CVs indicates that their luminosities do not correlate with the masses of the objects. The observed luminosity excesses in such stars show a close correlation with the post-common-envelope lifetime of the systems and should be investigated within the framework of the theory of their relaxation to the state of main-sequence stars.     

Infinitesimal orbits around lagrange points in the elliptic,restricted three-body problem

This study presents a method of obtaining asymptotic approximations for motions near a Lagrange point in the planar, elliptic, restricted three-body problem by using a von Zeipel-type method. The calculations are carried out for a second-order escape solution in the proximity of the equilateral Lagrange point, L ₄, where the primaries' orbital eccentricity is taken as the small parameter .     

Thermonuclear reaction rates from (p,n) reactions on targets withA = 92–122

From the experimentally measured (p,n) cross-sections for^92,94Zr,⁹³Nb,^95,96,98Mo,¹⁰³Rh,^107,109Ag,¹¹⁰Pd,¹¹⁵In,^117,122Sn nuclides, for proton energies below 7 MeV, thermonuclear reaction rates in the temperature range 1≤T ₉≤5(T₉=10⁹ K) have been extracted. These reaction rates have been fitted to a three parameter empirical expression proposed by Fowler.     

Limits on the changes in the gravitational constant from nucleosynthesis

Due to the recent all-sky, high-precision measurement of microwave background anisotropies by WMAP, a value for baryon-to-photon ratio η was obtained. At the WMAP value for η, the ⁴HE abundance was predicted. In this article we use a simple semi-analytical method with ⁴He predicted and measured values to place a limit on the variation of the gravitational constant G. We find using a conservative range for the measured values for Y _p , that ΔG/G is constrained between −0.26 and 0.15. If we assume a monotonic power law time dependence G∼t ^−β then β values is constrained between −0.008 and 0.0038, which translate into . This compares well with results obtained by others using full numerical analysis.      

Stable carbon isotope ratios in tree rings of co-occurring species from semi-arid tropics in Africa: Patterns and climatic signals

Although several proxies have been proposed to trace the course of environmental and climatological fluctuations, precise paleoclimate records from the tropics, notably from Africa are still sorely lacking today. Stable carbon isotopes (δ¹³C) in tree rings are an attractive record of climate. In this study, the patterns and climatic signals of δ¹³C ratios were determined on tree rings of deciduous (Acacia senegal, Acacia tortilis, Acacia seyal) and an evergreen (Balanites aegyptiaca) species, from a semi-arid Acacia Woodland in Ethiopia. δ¹³C inter-annual patterns are synchronous among the co-occurring species. A declining trend with time was observed in δ¹³C, notably for B. aegyptiaca, which could be due to anthropogenic increases in atmospheric CO₂ concentration and decrease in atmospheric δ¹³C. Tree ring δ¹³C values of all the species revealed significant negative correlation with precipitation amount but not with temperature and relative humidity. The δ¹³C series of the deciduous species shows a higher correlation (r = − 0.70 to − 0.78) with precipitation than the evergreen species (r = − 0.55). A master δ¹³C series, composed of the average of the three Acacia species, displayed stronger significant correlation (r = − 0.82) than any of the individual species δ¹³C series. The weak relationship between temperature and δ¹³C in this study indicates that photosynthetic rate is not a significant factor. Moisture stress, however, may have a direct impact on the stomatal conductance and explain the strong negative relationship between δ¹³C and precipitation. The results demonstrate the potential of δ¹³C in tree rings to reflect physiological responses to environmental changes as a vehicle for paleoclimatic reconstruction, which is important to understand tree response to past and future climate change.     

Geochemical record of the Holocene Jomon transgression and human activity in coastal lagoon sediments of the San'in district, SW Japan

Coastal lagoon muds were analyzed to evaluate changes in sedimentary environments by the Jomon transgression from the lower to middle Holocene age and human activities. Core samples from Lake Shinji, Southwest Japan were utilized, which cover the entire Holocene Nakaumi Formation (ca. 23-m thick), and comprise the Lower, Middle, Upper and Uppermost members. Total sulfur (TS) contents and Fe₂O₃/Al₂O₃ ratios increase from the boundary of Middle and Upper members, which is 1 m below the Kikai-Akahoya (K-Ah) volcanic ash of 6300 years BP. This change coincides to the pollen flora zone boundary of the Pinus–Abies and the Cyclobalanopsis–Castanopsis, suggesting transition to a warming climate. Chemical index of alteration (CIA) values [(ratio of Al to Al+Ca+Na+K)×100] and Rb/K ratios also show gradual increase from the middle part of the Upper member, due to its derivation from highly weathered source material probably formed under warming and rainy condition. Al₂O₃/TiO₂ and SiO₂/TiO₂ show little variation from the Lower to the Upper members, probably related to consistent feldspar composition in the source rocks, and homogeneously mixed clays. In the Uppermost member (from 1500 years), sharp increases in Ti/Zr and decreases in both Nb/Y and Zr/Y occurred, suggesting heavy mineral fractionation. This change was caused by iron sand processing called Kannanagashi and charcoal-making in the most mountainous regions. Soil erosion by these processes brought changes in mud composition, shown by the enrichment in Al₂O₃, and depletion in Zr and Cr. Human activities thus had severe impacts on sedimentary environments compared with the natural changes since the Jomon transgression.     

Bianchi type I two-fluid cosmological models with a variable G and Λ

This paper presents anisotropic, homogeneous two-fluid cosmological models in a Bianchi type I space–time with a variable gravitational constant G and cosmological constant Λ. In the two-fluid model, one fluid represents the matter content of the universe and another fluid is chosen to model the CMB radiation. We find a variety of solutions in which the cosmological parameter varies inversely with time t. We also discuss in detail the behavior of associated fluid parameters and kinematical parameters. This paper pictures cosmic history when the radiation and matter content of the universe are in an interactive phase. Here, Ω is closing to 1 throughout the cosmic evolution.      

Non-Existence Of <Emphasis Type="Italic">N</Emphasis>-Dimensional Static Plane Symmetric Solutions In Bimetric Relativity Theory

A problem of static plane symmetric metric in the perfect fluid, the mesonic massive scalar field and in their coupling is studied in Rosen’s (1973) bimetric theory of relativity. It was found that the matter field like either perfect fluid or mesonic massive scalar field or their coupling does not survive in bimetric theory of gravitation when the space–time is governed by n-dimensional static plane symmetric metric.     

The N-gon is not a local minimum of U 2 I for N > 7

A theorem of Palmore's concerning coplanar central configurations of equal mass bodies was shown to be false for all even N 6 by Slaminka and Woerner. Using a variation of that argument I prove that Palmore's Theorem is false for all N 6.Northwestern University     

INTEGRAL/XMM views on the MeV source GRO J1411-64

The COMPTEL unidentified source GRO J 1411-64 was observed by INTEGRAL and XMM-Newton in 2005. The Circinus Galaxy is the only source detected within the 4σ location error of GRO J1411-64, but in here excluded as the possible counterpart. At soft X-rays, 22 reliable and statistically significant sources (likelihood >10) were extracted and analyzed from XMM-Newton data. Only one of these sources, XMMU J141255.6-635932, is spectrally compatible with GRO J1411-64 although the fact the soft X-ray observations do not cover the full extent of the COMPTEL source position uncertainty make an association hard to quantify and thus risky. At the best location of the source, detections at hard X-rays show only upper limits, which, together with MeV results obtained by COMPTEL suggest the existence of a peak in power output located somewhere between 300–700 keV for the so-called low state. Such a spectrum resembles those in blazars or microquasars, and might suggest at work by the models accordingly. However, an analysis using a microquasar model consisting on a magnetized conical jet filled with relativistic electrons, shows that it is hard to comply with all observational constrains. This fact and the non-detection at hard X-rays introduce an a-posteriori question mark upon the physical reality of this source, what is discussed here.     

Evidence for a new MeV source observed by the COMPTEL experiment aboard CGRO

We report first evidence for a new unidentified and variable MeV source, located near the galactic plane at (l,b)∼(284.5°, 2.5°). The source, GRO J1036-55, is found at a significance level of ∼5.6σ by COMPTEL in its 3–10 MeV band. The energy spectrum indicates a spectral maximum at 3–4.3 MeV with a steep slope at higher energies. Since the COMPTEL 3–4.3 MeV data contain contamination by an instrumental background line, we performed several consistency checks, which all are consistent with an astrophysical nature of this emission feature.     

On the number of central configurations in the N-body problem

Central configurations are critical points of the potential function of the n-body problem restricted to the topological sphere where the moment of inertia is equal to constant. For a given set of positive masses m ₁,..., m _n we denote by N(m ₁, ..., m _n, k) the number of central configurations' of the n-body problem in ^k modulus dilatations and rotations. If m _{n 1},..., m _n, k) is finite, then we give a bound of N(m ₁,..., m _n, k) which only depends of n and k.     

Collective effects of stellar winds and unidentified gamma-ray sources

We study collective wind configurations produced by a number of massive stars, and obtain densities and expansion velocities of the stellar wind gas that is to be target, in this model, of hadronic interactions. We study the expected γ-ray emission from these regions, considering in an approximate way the effect of cosmic ray modulation. We compute secondary particle production (electrons from knock-on interactions and electrons and positrons from charged pion decay), and solve the loss equation with ionization, synchrotron, bremsstrahlung, inverse Compton, and expansion losses. We provide examples where configurations can produce sources for GLAST satellite, and the MAGIC, HESS, or VERITAS telescopes in non-uniform ways, i.e., with or without the corresponding counterparts. We show that in all cases we studied no EGRET source is expected.     

Radial velocities andDDO, BV photometry of Henry Draper G5-M stars near the North Galactic Pole

Radial velocities are given for some 900 stars within 15‡ of the North Galactic Pole, including almost all such stars classified G5 or later in theHenry Draper Catalogue. Luminosities, two-dimensional spectral classes, composition indices, and distances are derived for the majority of the sample throughDDO andBV photometry. More than half of the stars are classified as G5-K5 giants: they show a clear relationship between composition and velocity dispersion for the two Galactic componentsV andW, and a less well-defined trend forU. Four abundance groups exhibit characteristics which imply association with, respectively, the thick disk, old thin disk, young thin disk, and Roman’s “4150” group. The sample is contained within l kpc of the Galactic plane, and no trends with distance are evident.     

Why q-Expectation Values Must Be Used In Nonextensive Statistical Mechanics

There is a controversy in the area of nonextensive statistical mechanics regarding the form of the expectation value of a physical quantity. Two definitions have been discussed in the literature: one is the ordinary definition and the other is the normalized q-expectation value associated with the escort distribution. Here, it is proved that the normalized q-expectation value is the correct one to be employed. The Shore-Johnson theorem is used to show that the formalism with the normalized q-expectation value is theoretically consistent with minimum cross entropy principle, whereas the ordinary expectation value has to be excluded.     

Preliminary study of fluxes of major lipid biomarker classes in the water column and sediments of Lake Baikal, Russia

The application of biomarker climate proxies to lacustrine settings requires a thorough understanding of those processes that give rise to and mediate in the burial and preservation of organic matter in the sediments. This information is to date missing for Lake Baikal in Central Asia. The biogeochemistry of the lake cannot be considered analogous to that in other lacustrine environments given its enormous size, depth, remote location and unique biology. The aim of this paper is to report on the main compound classes in the water column and sediments. As part of an ongoing evaluation of the inputs and fluxes of organic matter in Lake Baikal, we have found that there are significant differences in the inputs and preservation of organic matter between the North and South Basins. Both basins have dominant algal input and a contribution from the terrestrial plants of the lake edges and surrounding environments. However, the concentration of organic material in the sediment traps and sediments of the South Basin is much higher than that of the North Basin. In addition, the South Basin contains much higher proportions of the more labile material than does the North Basin. This is likely due to the South Basin being free of surface ice for a much longer time than the North, and in consequence, primary producers having an overall longer productive season. There is some evidence of microbial activity in the sediment traps and sediments from both the North and South Basins, but it does not appear to be more predominant in one basin than the other. It is probable that the differences in the composition and concentration of biomarkers in sediments between basins is due to the length of and the intensity of the productive season, which is in turn influenced by the climate.     

Central configurations of the planar 1+N body problem

In this paper, we give a new derivation of the equations for the central configurations of the 1+n body problem. In the case of equal masses, we show that forn large enough there exists only one solution. Our lower bound forn improves by several orders of magnitude the one previously found by Hall.