Showing papers on "Binary system published in 2016"

Binary stellar mergers with marginally bound ejecta: excretion discs, inflated envelopes, outflows, and their luminous transients

Abstract: We study mass loss from the outer Lagrange point (L2) in binary stellar mergers and their luminous transients by means of radiative hydrodynamical simulations. Previously, we showed that for binary mass ratios 0.06 0.15. By contrast, for cold L2 mass-loss (\epsilon 0.8, the equatorial outflow instead remains marginally-bound and falls back to the binary over tens to hundreds of binary orbits, where it experiences additional tidal torqueing and shocking. As the bound gas becomes virialized with the binary, the luminosity of the system increases slowly at approximately constant photosphere radius, causing the temperature to rise. Subsequent evolution depends on the efficiency of radiative cooling. If the bound atmosphere is able to cool efficiently, as quantified by radiative diffusion time being shorter than the advection time (t_diff/t_adv 1 an isotropic wind is formed. Between these two extremes, an inflated envelope transports the heat generated near the binary to the surface by meridional flows. In all cases, the radiated luminosity reaches a fraction ~0.01 to 0.1 of Mdot v_orb^2/2, where Mdot is the mass outflow rate. We discuss the implications of our results for transients in the luminosity gap between classical novae and supernovae, such as V1309 Sco and V838 Mon.

Cool and luminous transients from mass-losing binary stars

Abstract: We study transients produced by equatorial disk-like outflows from catastrophically mass-losing binary stars with an asymptotic velocity and energy deposition rate near the inner edge which are proportional to the binary escape velocity v_esc. As a test case, we present the first smoothed-particle radiation-hydrodynamics calculations of the mass loss from the outer Lagrange point with realistic equation of state and opacities. The resulting spiral stream becomes unbound for binary mass ratios 0.06 < q < 0.8. For synchronous binaries with non-degenerate components, the spiral-stream arms merge at a radius of ~10a, where a is the binary semi-major axis, and the accompanying shock thermalizes about 10% of the kinetic power of the outflow. The mass-losing binary outflows produce luminosities reaching up to ~10^6 L_Sun and effective temperatures spanning 500 < T_eff < 6000 K, which is compatible with many of the class of recently-discovered red transients such as V838 Mon and V1309 Sco. Dust readily forms in the outflow, potentially in a catastrophic global cooling transition. The appearance of the transient is viewing angle-dependent due to vastly different optical depths parallel and perpendicular to the binary plane. We predict a correlation between the peak luminosity and the outflow velocity, which is roughly obeyed by the known red transients. Outflows from mass-losing binaries can produce luminous (10^5 L_Sun) and cool (T_eff < 1500 K) transients lasting a year or longer, as has potentially been detected by Spitzer surveys of nearby galaxies.

The Impact of Stellar Multiplicity on Planetary Systems, I.: The Ruinous Influence of Close Binary Companions

Abstract: The dynamical influence of binary companions is expected to profoundly influence planetary systems. However, the difficulty of identifying planets in binary systems has left the magnitude of this effect uncertain; despite numerous theoretical hurdles to their formation and survival, at least some binary systems clearly host planets. We present high-resolution imaging of 382 Kepler Objects of Interest (KOIs) obtained using adaptive-optics imaging and nonredundant aperture-mask interferometry (NRM) on the Keck-II telescope. Among the full sample of 506 candidate binary companions to KOIs, we super-resolve some binary systems to projected separations of 0.4; we instead only found 23 companions (a 4.6 sigma deficit), many of which must be wider pairs that are only close in projection. When the binary population is parametrized with a semimajor axis cutoff a_cut and a suppression factor inside that cutoff S_bin, we find with correlated uncertainties that inside a_cut = 47 +59/-23 AU, the planet occurrence rate in binary systems is only S_bin = 0.34 +0.14/-0.15 times that of wider binaries or single stars. Our results demonstrate that a fifth of all solar-type stars in the Milky Way are disallowed from hosting planetary systems due to the influence of a binary companion.

Vapor–Liquid Equilibrium Study of the Gamma-Valerolactone–Water Binary System

Abstract: Gamma-valerolactone (GVL) has been proposed as a biomass-based platform molecule. However, its vapor–liquid equilibrium has not been exhaustively studied yet. Antoine constants of GVL were determined and vapor–liquid equilibrium (VLE) data for water(1)–GVL(2) binary system were measured at atmospheric and reduced (50.66 and 10.1 kPa) pressures. The thermodynamic consistency was investigated by applying Herrington’s area test. It was established that no azeotropic mixture was formed for the water–GVL system in the full concentration range. Data were regressed using ChemCAD software to generate binary interaction parameters for Wilson, NRTL, and UNIQUAC activity coefficient models. Good agreements between calculated and experimental VLE data were obtained.

LIGO GW 150914 Gravitational Wave Detection and Generalized Gravitation Theory (MOG)

Abstract: The nature of gravitational waves in a generalized gravitation theory is investigated. The linearized field equations and the metric tensor quadrupole moment power and the decrease in radius of an inspiralling binary system of two compact objects are derived. The generalized Kerr metric describing a spinning black hole is determined by its mass $M$ and the spin parameter $a=cS/G_NM^2$. The LIGO-Virgo collaboration data is fitted with smaller binary black hole masses in agreement with the current electromagnetic, observed X-ray binary upper bound for a black hole mass, $M\lesssim 10M_\odot$.

Application of the Aldolization Reaction in Separating the Mixture of Ethylene Glycol and 1,2-Butanediol: Thermodynamics and New Separation Process

Abstract: The separation of ethylene glycol (EG) and 1,2-butanediol (1,2-BDO) azeotrope is a key technical problem in the synthesis process of EG via dimethyl oxalate (DMO) from syngas. On the basis of systematic investigation, aldolization is expected to be the solution to this industrial problem. Thus, the essential thermodynamics data were determined and correlated well by the corresponding thermodynamic equation, including the vapor pressure of 2-methyl-1,3-dioxolane (2MD) and 4-ethyl-2-methyl-1,3-dioxolane (4EMD), vapor–liquid equilibrium (VLE) data of binary mixture 2MD–4EMD at 101.3 kPa, and liquid–liquid equilibrium (LLE) data of binary system 4EMD–water at atmospheric conditions. The vapor–liquid–liquid equilibrium (VLLE) of binary system 4EMD–water has been successful predicted by LLE experimental data. Finally, the thermodynamics parameters were provided as a reference to design a separation process of the EG and 1,2-BDO mixture. The simulation and optimization results indicate that EG and 1,2-BDO could ...

A solar-type stellar companion to a deep contact binary in a quadruple system

Abstract: The four-color (B, V, R-c, I-c) light curves of V776 Cas are presented and analyzed using the Wilson-Devinney method. It is discovered that V776 Cas is an early F-type (F2V) overcontact binary with a very high contact degree (f = 64.6%) and an extremely low-mass ratio (q = 0.130), which indicate that it is at the final evolutionary stage of cool short-period binaries. The mass of the primary and secondary stars are calculated to be M-1 = 1.55 (+/- 0.04) M circle dot, M-2 = 0.20(+/- 0.01) M circle dot. V776 Cas is supposed to be formed from an initially detached binary system via the loss of angular momentum due to the magnetic wind. The initial masses of the present primary and secondary components are calculated to be M-1i = 0.86(+/- 0.10) M circle dot and M-2i = 2.13(+/- 0.04) M circle dot. The observed-calculated curve exhibits a cyclic period variation, which is due to the light-travel time effect caused by the presence of a third component with a period of 23.7 years. The mass of the third component is estimated to be M3 = 1.04(+/- 0.03) M circle dot and the orbital inclination of the third component is calculated to be i' = 33 degrees.1. The distance of the binary system to the mass center of the triple system is calculated to be a'(12) = 3.45 AU. The presence of the close-in tertiary component may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system.

Thermodynamic Reassessment of the Nd-Fe-B Ternary System

Abstract: The Nd-B binary system and Nd-Fe-B ternary system were thermodynamically reassessed with the aim of obtaining more reasonable thermodynamic parameters and more accurate phase relations. Based on the metastable experimental information, a reasonable, self-consistent, and comprehensive thermodynamic description of the Nd-Fe-B ternary system considering the metastable phases Fe3B, Fe23Nd2B3, and Fe17Nd2B has been developed.

Competitive adsorption of VOCs from binary aqueous mixtures on zeolite ZSM-5

Abstract: Adsorption equilibria of methyl tert-butyl ether (MTBE)/toluene (TOL), and 1,2-dichloroethane (DCE)/MTBE binary mixtures in aqueous solution on ZSM-5 were measured over a wide range of concentrations. In comparison with the single-component data, the loading of all of the three compounds was reduced in the presence of a second component in the mixture. The binary system was described by a competitive dual site Langmuir adsorption isotherm. The model was chosen on the basis of the results obtained from X-ray diffraction studies of the adsorbent material loaded with equimolar binary mixtures. Rietveld structure refinements provide information about the relative position of molecules inside the structure after TOL-MTBE and DCE-MTBE mixture adsorption. The short intermolecular distances between the adsorption sites of MTBE, DCE and TOL inside the zeolite framework clearly prevent the simultaneous occupancy of one site by more than one component, when these compounds are adsorbed from binary mixtures.

Crystallization of ZrSiO4 from a SiO2–ZrO2 Binary System: The Concomitant Effects of Heat Treatment Temperature and TiO2 Additions

Abstract: The concomitant effects of adding varied amounts of TiO2 and temperature of heat treatment on the crystallization of ZrSiO4 from SiO2–ZrO2 binary systems were investigated. The results showed that the t-ZrO2 phase is stabilized in the amorphous SiO2 network, and the simultaneous occurrence of SiO2 crystallization along with the tetragonal zirconia (t-ZrO2) → monoclinic zirconia (m-ZrO2) phase transition tends to activate the reaction between m-ZrO2 and SiO2 to yield ZrSiO4 at elevated temperatures. The formation of metastable ZrTiO4 is also witnessed in the intermediate temperatures that were dependent on TiO2 content, and its dissociation into their individual ZrO2 and TiO2 oxides resulted in ZrSiO4 formation. The Ti4+ occupancy at the Zr4+ lattice sites ensured enhanced crystallization of ZrSiO4, and the limit of Ti4+ occupancy is determined as 9%. Excess TiO2 discarded from the ZrSiO4 lattice gets crystallized into rutile TiO2 (r-TiO2).

A low-mass-ratio and deep contact binary as the progenitor of the merger V1309 Sco

Abstract: Nova Sco 2008 (=V1309 Sco) is an example of a V838 Mon type eruption rather than a typical classical nova. This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary. It is the first stellar merger that was identified to be undergoing a common envelope transient. To understand the properties of its binary progenitor, the pre-outburst light curves were analyzed by using the W-D method. The photometric solution of the 2002 light curve shows that it is a deep contact binary ( f = 89.5(±40.5)%) with a mass ratio of 0.094. The asymmetry of the light curve is explained by the presence of a dark spot on the more massive component. The extremely high fill-out factor suggests that the merging of the contact binary is driven by dynamical mass loss from the outer Lagrange point. However, the analysis of the 2004 light curve indicates that no solutions were obtained even at an extremely low mass ratio of q = 0.03. This suggests that the common convective envelope of the binary system disappeared and the secondary component spiraled into the envelope of the primary in 2004. Finally, the ejection of the envelope of the primary produced the outburst.

Thermodynamic coarsening arrested by viscous fingering in partially miscible binary mixtures

Abstract: We study the evolution of binary mixtures far from equilibrium, and show that the interplay between phase separation and hydrodynamic instability can arrest the Ostwald ripening process characteristic of nonflowing mixtures. We describe a model binary system in a Hele-Shaw cell using a phase-field approach with explicit dependence of both phase fraction and mass concentration. When the viscosity contrast between phases is large (as is the case for gas and liquid phases), an imposed background flow leads to viscous fingering, phase branching, and pinch off. This dynamic flow disorder limits phase growth and arrests thermodynamic coarsening. As a result, the system reaches a regime of statistical steady state in which the binary mixture is permanently driven away from equilibrium.

Excess properties and spectroscopic studies of binary system 1,4-butanediol + water at T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K

Abstract: Density and dynamic viscosity data were measured over the whole concentration range for the binary system 1,4-butanediol (1) + water (2) at T = (293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K as a function of composition under atmospheric pressure. Based on density and dynamic viscosity data, excess molar density (ρE), dynamic viscosity deviation (Δν) and excess molar volume (VmE) were calculated. From the dynamic viscosity data, excess Gibbs energies (ΔG*E), Gibbs free energy of activation of viscous flow (ΔG*), enthalpy of activation for viscous flow (ΔH*) and entropy of activation for viscous flow (ΔS*) were also calculated. The ρE, VmE, Δν and ΔG*E values were correlated by a Redlich−Kister-type function to obtain the coefficients and to estimate the standard deviations between the experimental and calculated quantities. Based on FTIR and UV spectral results, the intermolecular interaction of 1,4-butanediol with H2O was discussed.

Design analysis of fixed-bed synergic adsorption of heavy metals and acid blue 25 on activated carbon

Abstract: This study reports the multicomponent adsorption of dye AB25, nickel (Ni2+) and zinc (Zn2+) ions on an activated carbon using binary mixtures of metal and dye, and packed bed columns at different operating conditions. Design parameters of packed bed adsorption columns have been calculated using the breakthrough curves and Thomas model, and an analysis has been performed to determine the effect and magnitude of the synergistic adsorption on the design parameters and adsorbent performance. Results showed that there is a strong synergistic adsorption of heavy metals on activated carbon caused by the presence of dye AB25 in binary mixtures. The magnitude of this synergistic adsorption effect depends on the dynamic operating conditions and type of heavy metal present in the binary system. The presence of dye AB25 in the binary mixtures caused a better degree of column utilization because the values of mass transfer zone decreased with respect to the results obtained with mono-component solutions. Metal...

PHOTOMETRIC AND PERIOD INVESTIGATION OF THE LATE F-TYPE OVERCONTACT BINARY II UMa

Abstract: II UMa is a late F-type (F5) contact binary with a close-in tertiary and a distant visual companion. According to the four-color (BVRcIc) light curves' solutions of II UMa, it is a high fill-out (f = 86.6%) and low-mass ratio (q = 0.172) contact binary system, which indicates that it is at the late evolutionary stage of late-type tidal-locked binary stars. The masses of the primary star and secondary star are calculated to be M-1 = 1.99M(circle dot) and M-2 = 0.34M(circle dot). The primary star has evolved from the zero-age main sequence, but it still appeared before the terminal-age main sequence, and the secondary star is even more evolved. Considering the mass ratio (M-3/M-1 = 0.67) obtained by spectroscopic observations, the mass of the close-in tertiary is estimated to be M-3 = 1.34M(circle dot). The period variations of the binary system are investigated for the first time. According to the observed-calculated (O-C) curve analysis, a continuous period increase at a rate of dP/dt = 4.88 x 10(-7) day yr(-1) is determined. The parabolic variation in the O-C curve may be part of a cyclic period of change, or the combined period of change of a parabolic variation and a cyclic one. More instances of minimum light are needed to confirm this. The presence of the tertiary component may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system during the pre-contact stage.

Adsorption behavior of Co(II) and Ni(II) from aqueous solutions onto titanate nanotubes

Abstract: Adsorption of Co2+ and Ni2+ from aqueous solutions onto titanate nanotubes (TNTs) synthesized by hydrothermal method in single and binary systems was investigated. The prepared TNTs were completely characterized showing very high surface area compared to previous studies (320 m2/g). The high surface area showed very good optimum removal conditions compared with previous studies (60 min contact time, 0.1 g TNTs dose at pH 5 and room temperature) with high adsorption capacity compared with previous studies as well as conventional adsorbent. Langmuir and Freundlich isothermal models were fitted during this study and Dubinin–Kaganer–Radushkevich isotherms showed physisorption with exclusion of ion exchange mechanism. Pseudo first and second-order kinetics were studied showing more fitting to pseudo second-order equation. Binary system and calculation of separation coefficient showed high ability for Co2+ adsorption by TNTs than Ni+2 in binary system.