Showing papers on "Binary system published in 2015"

New Nanocrystalline Materials: A Previously Unknown Simple Cubic Phase in the SnS Binary System

Abstract: We report a new phase in the binary SnS system, obtained as highly symmetric nanotetrahedra. Due to the nanoscale size and minute amounts of these particles in the synthesis yield, the structure was exclusively solved using electron diffraction methods. The atomic model of the new phase (a = 11.7 A, P213) was deduced and found to be associated with the rocksalt-type structure. Kramers–Kronig analysis predicted different optical and electronic properties for the new phase, as compared to α-SnS.

Adsorption of copper and lead in single and binary metal system onto Fumaria indica biomass

Abstract: Among heavy metals, lead and copper pose a significant threat to the due to their toxicity, incremental accumulation in the food chain and persistence in the ecosystem. Lead and copper are introduced into water from various industries and other human activities. Present study was aimed to remove lead and copper from aqueous media using Fumaria indica biomass as a function of metal ions initial concentration. Both metal removal was investigated in single and binary system. For comparison isotherm models i.e., Langmuir and Freundlich were applied on experimental adsorption data. Results showed that the copper behavior was different in single and binary metal system, whereas lead adsorption remained the same in both single and binary metal systems. The Freundlich isotherm model fitted well to the adsorption data of both single and binary metal system. The thermodynamic parameters i.e., ∆G 0 , was measured to get insight into adsorption phenomenon and negative value of ∆G 0

Misaligned gas discs around eccentric black hole binaries and implications for the final-parsec problem

Abstract: We investigate the evolution of low mass (Md /Mb = 0.005) misaligned gaseous discs around eccentric supermassive black hole (SMBH) binaries. These are expected to form from randomly oriented accretion events onto a SMBH binary formed in a galaxy merger. When expanding the interaction terms between the binary and a circular ring to quadrupole order and averaging over the binary orbit, we expect four non-precessing disc orientations: aligned or counter-aligned with the binary, or polar orbits around the binary eccentricity vector with either sense of rotation. All other orientations precess around either of these, with the polar precession dominating for high eccentricity. These expectations are borne out by smoothed particle hydrodynamics simulations of initially misaligned viscous circumbinary discs, resulting in the formation of polar rings around highly eccentric binaries in contrast to the co-planar discs around circular binaries. Moreover, we observe disc tearing and violent interactions between differentially precessing rings in the disc significantly disrupting the disc structure and causing gas to fall onto the binary with little angular momentum. While accretion from a polar disc may not promote SMBH binary coalescence (solving the `final-parsec problem'), ejection of this infalling low-angular momentum material via gravitational slingshot is a possible mechanism to reduce the binary separation. Moreover, this process acts on dynamical rather than viscous time scales, and so is much faster.

On the formation of ultraluminous x-ray sources with neutron star accretors: the case of m82 x-2

Abstract: The recent discovery of a neutron star accretor in the ultra-luminous X-ray (ULX) source M82 X-2 challenges our understanding of high-mass X-ray binary formation and evolution. By combining binary population synthesis and detailed mass-transfer models, however, we show that the binary parameters of M82 X-2 are not surprising provided non-conservative mass transfer is allowed. Specifically, the donor-mass lower limit and orbital period measured for M82 X-2 lie near the most probable values predicted by population synthesis models, and systems such as M82 X-2 should exist in approximately 13% of the galaxies with a star formation history similar to M82. We conclude that the binary system that formed M82 X-2 is most likely less than 50 Myr old and contains a donor star which had an initial mass of approximately 8–10 M , while the NS’s progenitor star had an initial mass in the 8–25 M range. The donor star still currently resides on the main sequence, and is capable of continued MT on the thermal timescale, while in the ULX regime, for as long as 400,000 yr.

Density, Refractive Index, and Speed of Sound of the Binary Mixture of 1-Butyl-3-methylimidazolium Tetrafluoroborate + N-Vinyl-2-pyrrolidinone from T = (298.15 to 323.15) K at Atmospheric Pressure

Abstract: Density (ρ), refractive index (nD), and speed of sound (u) values are measured for the binary mixture of 1-butyl-3-methylimidazolium tetrafluoroborate (1) and N-vinyl-2-pyrrolidinone (2) over the entire range of mole fractions at temperatures from T = (298.15 to 323.15) K under atmospheric pressure. Using the basic experimental data, various acoustic and thermodynamic parameters are calculated and are discussed in terms of molecular interactions between the present investigated binary system. The excess values are fitted to the Redlich–Kister polynomial equation to estimate the binary coefficients and standard deviation between the experimental and calculated values. Further, the molecular interactions in the binary mixture system are analyzed using the experimental FT-IR spectrum recorded at room temperature.

Phase Diagram of the Li4GeS4–Li3PS4 Quasi-Binary System Containing the Superionic Conductor Li10GeP2S12

Abstract: A phase diagram is constructed for the quasi-binary Li4GeS4–Li3PS4 system containing the lithium superionic conductor Li10GeP2S12 (LGPS), having an LGPS-type structure, and the β-Li3PS4-type phase, having a thio-LISICON structure. The LGPS and thio-LISICON intermediate compounds are found to exhibit solid solution ranges and show incongruent melting at 650°C and 560°C, respectively. The end-member Li4GeS4 has a compositional range of 0 < k < 0.3 in [(1−k) Li4GeS4 + k Li3PS4], while the other end-member γ-Li3PS4 has no solid solution range. The crystal structures appearing in the binary systems are the α-, β-, and γ-type Li3PS4 structures and the LGPS-type structure, and these are formed by PS4 tetrahedra with different arrangements in each structure. The phase and structural relationships between the compounds appearing in the Li4GeS4–Li3PS4 system are thus clarified.

Ultra-low Sintering Temperature Microwave Dielectric Ceramics Based on Na2O-MoO3 Binary System

Abstract: The compounds in Na2O-MoO3 system were prepared by the solid-state reaction route. The phase composition, crystal structures, microstructures, and microwave dielectric properties of the compounds have been investigated. This series of compounds can be sintered well at ultra-low temperatures of 505°C–660°C. The sintered samples exhibit good microwave dielectric properties, with the relative permittivities (er) of 4.1–12.9, the Q × f values of 19900–62400 GHz, and the τf values of −115 ppm/°C to −57 ppm/°C. Among the eight compounds in this binary system, three kinds of single-phase ceramics, namely Na2MoO4, Na2Mo2O7 and Na6Mo11O36 were formed. Furthermore, the relationship between the structure and the microwave dielectric properties in this system has been discussed. The average NaI-O and MoVI-O bond valences have an influence on the sintering temperatures in Na2O-MoO3 system. The large valence deviations of Na and Mo lead to a large temperature coefficient of resonant frequency. The X-ray diffraction and backscattered electron image results show that Na2MoO4 doesn't react with Ag and Al at 660°C. Also, Na2Mo2O7 has a chemical compatibility with Al at 575°C.

Sdss j001641-000925: the first stable red dwarf contact binary with a close-in stellar companion

Abstract: SDSS J001641-000925 is the first red dwarf contact binary star with an orbital period of 0.19856 days that is one of the shortest known periods among M-dwarf binary systems. The orbital period was detected to be decreasing rapidly at a rate of P similar to 8 s yr(-1). This indicated that SDSS J001641-000925 was undergoing coalescence via a dynamical mass transfer or loss and thus this red dwarf contact binary is dynamically unstable. To understand the properties of the period change, we monitored the binary system photometrically from 2011 September 2 to 2014 October 1 by using several telescopes in the world and 25 eclipse times were determined. It is discovered that the rapid decrease of the orbital period is not true. This is contrary to the prediction that the system is merging driven by rapid mass transfer or loss. Our preliminary analysis suggests that the observed minus calculated (O-C) diagram shows a cyclic oscillation with an amplitude of 0.00255 days and a period of 5.7 yr. The cyclic variation can be explained by the light travel time effect via the presence of a cool stellar companion with a mass of M-3 sin i' similar to 0.14M(circle dot). The orbital separation between the third body and the central binary is about 2.8AU. These results reveal that the rarity of red dwarf contact binaries could not be explained by rapidly dynamical destruction and the presence of the third body helps to form the red dwarf contact binary.

WIYN Open Cluster Study. XXXVI. Spectroscopic Binary Orbits in NGC 188

Abstract: We present 98 spectroscopic binary orbits resulting from our ongoing radial-velocity survey of the old (7 Gyr) open cluster NGC 188. All but 13 are high-probability cluster members based on both radial-velocity and proper-motion membership analyses. Fifteen of these member binaries are double lined. Our stellar sample spans a magnitude range of 10.8 <=V<= 16.5 (1.14-0.92 Msun) and extends spatially to 17 pc (~13 core radii). All of our binary orbits have periods ranging from a few days to on the order of 10^3 days, and thus are hard binaries that dynamically power the cluster. For each binary, we present the orbital solutions and place constraints on the component masses. Additionally, we discuss a few binaries of note from our sample, identifying a likely blue straggler-blue straggler binary system (7782), a double-lined binary with a secondary star which is under-luminous for its mass (5080), two potential eclipsing binaries (4705 and 5762), and two binaries which are likely members of a quadruple system (5015a and 5015b).

Two-State or Non-Two-State? An Excess Spectroscopy-based Approach to Differentiate the Existing Forms of Molecules in Liquids Mixtures.

Abstract: Characterization/identification of the clusters/associates in liquids has long been a challenging topic. In this paper, we report a method to identify molecules with two different existing forms in a binary liquid solution. In this so-called two-state situation, the excess infrared spectra of a vibration mode of the respective molecule will show identical band shape if the other component is transparent in the region. More conveniently, the positions of the positive peak, negative peak, and zero-value will be seen to be fixed with varying compositions of the binary system. In the case of non-two-state mixtures, for example the mere solvation of solute by solvent, those positions will be variable. The conclusions are supported/demonstrated by computational simulation and experiments on two binary systems, D2O-H2O and C6F5I-cyclo-C6H12.

Phase Diagram for the NaBH4–KBH4 System and the Stability of a Na1–xKxBH4 Solid Solution

Abstract: The binary system NaBH4–KBH4 has been systematically investigated by several complementary techniques, including in situ synchrotron radiation powder X-ray diffraction (SR-PXD), thermal analysis, and in situ 11B and 23Na magic-angle spinning (MAS) NMR. Full solubility in the system NaBH4–KBH4 and formation of a solid solution, Na1–xKxBH4, 0 110 °C, are observed. The Na1–xKxBH4 solid solution is most clearly observed by 11B MAS NMR, which reveals a binomial distribution of Na+ and K+ ions over the six metal sites in the first coordination sphere of the BH4– unit, i.e., seven almost equally distinct peaks in the range −36.4 to −42.6 ppm with a systematic change of 1.0 ± 0.1 ppm toward lower frequency for each replacement of K+ by Na+. The solid solution Na1–xKxBH4 is metastable at room temperature, and 75% of Na0.5K0.5BH4 has separated into NaBH4 and KBH4 after 24 h at ∼24 °C, as observed by in situ 23Na and 11B MAS NMR. The composition 0.682NaBH4–0.318KBH4 has the lowest m...

The TeO2‐Na2O System: Thermal Behavior, Structural Properties, and Phase Equilibria

Abstract: Thermal behavior, structural properties, and phase equilibria of the (100−x)TeO2-xNa2O system were studied in the 5 ≤ x ≤ 50 mol% composition range. Investigation of glass formation behavior in the binary system was realized, and the glass formation range was determined as 7.5 ≤ x ≤ 40 mol%. Differential thermal analysis (DTA) and Fourier transform infrared (FTIR) spectroscopy techniques were used for thermal and structural characterization of the glasses. Influence of Na2O content on glass transition temperature (Tg), glass stability (∆T), density (ρ), molar volume (VM), oxygen molar volume (VO), and oxygen packing density (OPD) values of sodium tellurite glasses was evaluated considering the structural transformations in the glass network. For the phase equilibria studies, DTA, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive X-ray (SEM/EDS) techniques were utilized to characterize the heat-treated samples. According to the phase equilibria studies, three eutectic regions were detected in the 0 < x < 50 mol% composition range of the (100−x)TeO2-xNa2O system. A new invariant endothermic reaction was detected for the compositions between 40 ≤ x ≤ 45 mol%. Na2O.8TeO2 (11.11 mol% Na2O) compound that was claimed to exist in the binary system in the literature was found to be the metastable δ-TeO2 phase.

Thermodynamics of the formation of sulfuric acid dimers in the binary (H 2 SO 4 –H 2 O) and ternary (H 2 SO 4 –H 2 O–NH 3 ) system

Abstract: . Sulfuric acid is an important gas influencing atmospheric new particle formation (NPF). Both the binary (H2SO4–H2O) system and the ternary system involving ammonia (H2SO4–H2O–NH3) may be important in the free troposphere. An essential step in the nucleation of aerosol particles from gas-phase precursors is the formation of a dimer, so an understanding of the thermodynamics of dimer formation over a wide range of atmospheric conditions is essential to describe NPF. We have used the CLOUD chamber to conduct nucleation experiments for these systems at temperatures from 208 to 248 K. Neutral monomer and dimer concentrations of sulfuric acid were measured using a chemical ionization mass spectrometer (CIMS). From these measurements, dimer evaporation rates in the binary system were derived for temperatures of 208 and 223 K. We compare these results to literature data from a previous study that was conducted at higher temperatures but is in good agreement with the present study. For the ternary system the formation of H2SO4·NH3 is very likely an essential step in the formation of sulfuric acid dimers, which were measured at 210, 223, and 248 K. We estimate the thermodynamic properties (dH and dS) of the H2SO4·NH3 cluster using a simple heuristic model and the measured data. Furthermore, we report the first measurements of large neutral sulfuric acid clusters containing as many as 10 sulfuric acid molecules for the binary system using chemical ionization–atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometry.

Time Sequence Spectroscopy of AW UMa. The 518 nm Mg i Triplet Region Analyzed With Broadening Functions

Abstract: High-resolution spectroscopic observations of AW UMa, obtained on three consecutive nights with a median time resolution of 2.1 minutes, have been analyzed using the broadening function method in the spectral window of 22.75 nm around the 518 nm Mg i triplet region. Doppler images of the system reveal the presence of vigorous mass motions within the binary system; their presence puts into question the solid-body rotation assumption of the contact binary model. AW UMa appears to be a very tight, semi-detached binary; the mass transfer takes place from the more massive to the less massive component. The primary, a fast-rotating star with km s−1, is covered with inhomogeneities: very slowly drifting spots and a dense network of ripples more closely participating in its rotation. The spectral lines of the primary show an additional broadening component (called the "pedestal") that originates either in the equatorial regions, which rotate faster than the rest of the star by about 50 km s−1, or in an external disk-like structure. The secondary component appears to be smaller than predicted by the contact model. The radial velocity field around the secondary is dominated by accretion of matter transferred from (and possibly partly returned to) the primary component. The parameters of the binary are and , . The mass ratio, , while still the most uncertain among the spectroscopic elements, is substantially different from the previous numerous and mutually consistent photometric investigations which were based on the contact model. It should be studied why photometry and spectroscopy give such discrepant results and whether AW UMa is an unusual object or if only very high-quality spectroscopy can reveal the true nature of W UMa-type binaries.

Stability of orbits near large mass ratio binary systems

Abstract: With improved observational capabilities and techniques, an increasing number of exoplanets have been discovered to orbit in the vicinity of binary star systems. In this investigation, periodic motions near a large mass ratio binary are explored within the context of the circular restricted three-body problem. Specifically, stability analysis is used to explore the effect of the mass ratio on the structure of families of periodic orbits. Such analysis is useful in a variety of applications, including the determination of potentially stable exoplanet motions near a binary star.