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Sample records for close pg1159 binary

  1. Iron Abundance in the Prototype PG 1159 Star, GW Vir Pulsator PG 1159-035, and Related Objects

    NASA Technical Reports Server (NTRS)

    Werner, K.; Rauch, T.; Kruk, J. W.; Kurucz, R. L.

    2011-01-01

    We performed an iron abundance determination of the hot, hydrogen deficient post-AGB star PG 1159-035. which is the prototype of the PG 1159 spectral class and the GW Vir pulsators, and of two related objects (PG 1520+525, PG 1144+005), based on the first detection of Fe VIII lines in stellar photospheres. In another PG 1159 star. PG 1424+535. we detect Fe VII lines. In all four stars, each within T(sub eff) = 110,000-150,000 K, we find a solar iron abundance. This result agrees with our recent abundance analysis of the hottest PG 1159 stars (T(sub eff) = 150,000-200,000 K) that exhibit Fe x lines. On the whole, we find that the PG 1159 stars are not significantly iron deficient, in contrast to previous notions.

  2. Discovery of a new PG 1159 (GW Vir) pulsator

    NASA Astrophysics Data System (ADS)

    Kepler, S. O.; Fraga, Luciano; Winget, Don Earl; Bell, Keaton; Córsico, Alejandro H.; Werner, Klaus

    2014-08-01

    We report the discovery of pulsations in the spectroscopic PG 1159 type pre-white dwarf SDSS J075415.12 + 085232.18. Analysis of the spectrum by Werner et al. indicated Teff = 120 000 ± 10 000 K, log g = 7.0 ± 0.3, mass {M}=0.52 ± 0.02 M_{⊙}, C/He = 0.33 by number. We obtained time series images with the SOAR 4.1 m telescope and 2.1 m Otto Struve telescope at McDonald Observatory and show the star is also a variable PG 1159 type star, with dominant period of 525 s.

  3. The Domains of Instability for the Pulsating PG 1159 Stars

    NASA Astrophysics Data System (ADS)

    Quirion, P.-O.; Fontaine, G.; Brassard, P.; Herwig, F.

    2005-07-01

    The fact that we find pulsating and nonpulsating stars mixed together in the PG 1159 region of the log g-Teff diagram has been a long standing puzzle. The poor understanding of the driving mechanism in those stars has been the reason why it has taken so long to address properly this problem. Following the work of Saio (1996) and Gautchy (1997) based on the OPAL opacities, Quirion et al. (2004) recently showed that we are now able to understand and reproduce the ranges of observed periods in the pulsating PG 1159 stars in terms of the original κ-mechanism associated with the partial ionization of the K-shell electrons of C and O which, along with He, make up the composition of the envelope of those stars. Contrary to others, those three studies agree in that no composition gradients are needed between the atmospheric layers and the driving region. Furthermore, the cohabitation of pulsating and nonpulsating PG 1159 stars is naturally explained in terms of a dispersion in atmospheric parameters and in terms of a variation in surface composition from star to star. In particular, the most He-rich stars tend to be stable. We go beyond the findings discussed by Quirion et al. (2004) in this paper, and present the results of additional calculations aimed at describing better the role of the chemical composition (in particular the role of metallicity) as well as that of the stellar mass on the boundaries of the instability domain in the log g-Teff plane.

  4. The domains of instability for the pulsating PG1159 stars.

    SciTech Connect

    Quirion, P.-O.; Fontaine, Gilles.; Brassard, Pierre; Herwig, F. H.

    2004-01-01

    The fact that we find pulsating and nonpulsating stars mixed together in the PG 1159 region of the log g - T{sub eff} diagram has been a long standing puzzle. The poor understanding of the driving mechanism in those stars has been the reason why it has taken so long to address properly this problem. Following the work of Saio (1996) and Gautschy (1997) based on the OPAL opacities, Quirion, Fontaine, & Brassard (2004) recently showed that we are now able to understand and reproduce the ranges of observed periods in the pulsating PG 1159 stars in terms of the original {kappa}-mechanism associated with the partial ionization of the K-shell electrons of C and O which, along with He, make up the composition of the envelope of those stars. Contrary to others, those three studies agree in that no composition gradients are needed between the atmospheric layers and the driving region. Furthermore, the cohabitation of pulsating and nonpulsating PG 1159 stars is naturally explained in terms of a dispersion in atmospheric parameters and in terms of a variation in surface composition from star to star. In particular, the most He-rich stars tend to be stable. We go beyond the findings discussed by Quirion et al. (2004) in this paper, and present the results of additional calculations aimed at describing better the role of the chemical composition (in particular the role of metallicity) as well as that of the stellar mass on the boundaries of the instability domain in the log g - T{sub eff} plane.

  5. The far-ultraviolet spectra of "cool" PG 1159 stars

    NASA Astrophysics Data System (ADS)

    Werner, K.; Rauch, T.; Kruk, J. W.

    2015-10-01

    We present a comprehensive study of Far Ultraviolet Spectroscopic Explorer (FUSE) spectra (912-1190 Å) of two members of the PG 1159 spectral class, which consists of hydrogen-deficient (pre-) white dwarfs with effective temperatures in the range Teff = 75 000-200 000 K. As two representatives of the cooler objects, we have selected PG 1707+427 (Teff = 85 000 K) and PG 1424+535 (Teff = 110 000 K), complementing a previous study of the hotter prototype PG 1159-035 (Teff = 140 000 K). The helium-dominated atmospheres are strongly enriched in carbon and oxygen, therefore, their spectra are dominated by lines from C iii-iv and O iii-vi, many of which were never observed before in hot stars. In addition, lines of many other metals (N, F, Ne, Si, P, S, Ar, Fe) are detectable, demonstrating that observations in this spectral region are most rewarding when compared to the near-ultraviolet and optical wavelength bands. We perform abundance analyses of these species and derive upper limits for several undetected light and heavy metals including iron-group and trans-iron elements. The results are compared to predictions of stellar evolution models for neutron-capture nucleosynthesis and good agreement is found. Appendix A is available in electronic form at http://www.aanda.org

  6. Asteroseismology of the PG 1159 star PG 0122+200

    NASA Astrophysics Data System (ADS)

    Fu, J.-N.; Vauclair, G.; Solheim, J.-E.; Chevreton, M.; Dolez, N.; O'Brien, M. S.; Kim, S.-L.; Park, B.-G.; Handler, G.; Medupe, R.; Wood, M.; Gonzalez Perez, J.; Hashimoto, O.; Kinugasa, K.; Taguchi, H.; Kambe, E.; Provencal, J.; Dreizler, S.; Schuh, S.; Leibowitz, E.; Lipkin, Y.; Zhang, X.-B.; Paparo, M.; Szeidl, B.; Virághalmy, G.; Zsuffa, D.

    2007-05-01

    Context: The variable pre-white dwarf PG 1159 stars (GW Vir) are g-mode non-radial pulsators. Asteroseismology puts strong constraints on their global parameters and internal structure. PG 0122+200 defines the red edge of the instability strip and its evolutionary timescale is predicted to be dominated by neutrino emission. Its study offers the opportunity to better understand the instability mechanism and to validate the physics of the neutrino production in dense plasma. Aims: To achieve such a goal requires determining precisely its fundamental parameters. This is the goal of this paper. Methods: We present new multi-site photometric observations obtained in 2001 and 2002. Together with previous data, they allow us to detect 23 frequencies, composed of 7 triplets and 2 single frequencies, which are used to constrain its internal structure and derive its fundamental parameters. Results: All the observed frequencies correspond to ℓ=1 g-modes. The period distribution shows a signature of mode trapping from which we constrain the He-rich envelope mass fraction to be -6.0≤ log(qy) ≤ -5.3. The comparison of the mode trapping amplitudes among GW Vir stars suggests that the mass-loss efficiency must decrease significantly below T_eff≤ 140 kK. We measure an average period spacing of 22.9 s from which we derive a mass of 0.59±0.02 M⊙. From the triplets we measure a mean rotational splitting of 3.74 μHz and a rotational period of 1.55 days. We derive an upper limit to the magnetic field of B≤4×103 G. The luminosity (log L/L⊙ = 1.3±0.5) and the distance (D = 0.7^+1.0_-0.4 kpc) are only weakly constrained due to the large uncertainty on the spectroscopically derived surface gravity and the absence of a measured parallax. Conclusions: From the asteroseismic mass, the ratio of the neutrino luminosity on the photon luminosity is 1.6±0.2 confirming that the PG 0122+200 evolutionary time scale should be dominated by neutrino cooling. A measurement of dot{P} for

  7. Asteroseismology of the DOV star PG 1159 - 035 with the Whole Earth Telescope

    NASA Technical Reports Server (NTRS)

    Winget, D. E.; Nather, R. E.; Clemens, J. C.; Provencal, J.; Kleinman, S. J.; Bradley, P. A.; Wood, M. A.; Claver, C. F.; Frueh, M. L.; Grauer, A. D.

    1991-01-01

    Results are reported from 264.1 hr of nearly continuous time-series photometry on the pulsating prewhite dwarf star (DPV) PG 1159 - 035. The power spectrum of the data set is completely resolved into 125 individual frequencies; 101 of them are identified with specific quantized pulsation modes, and the rest are completely consistent with such modal assignment. It is argued that the luminosity variations are certainly the result of g-mode pulsations. Although the amplitudes of some of the peaks exhibit significant variations on the time scales of a year or so, the underlying frequency structure of the pulsations is stable over much longer intervals. The existing linear theory is invoked to determine, or strongly constrain, many of the fundamental physical parameters describing this star. Its mass is found to be 0.586 solar mass, is rotation period 1.38 days, its magnetic field less than 6000 G, its pulsation and rotation axes to be aligned, and its outer layers to be compositionally stratified.

  8. Asteroseismology of RXJ 2117+3412, the hottest pulsating PG 1159 star

    NASA Astrophysics Data System (ADS)

    Vauclair, G.; Moskalik, P.; Pfeiffer, B.; Chevreton, M.; Dolez, N.; Serre, B.; Kleinman, S. J.; Barstow, M.; Sansom, A. E.; Solheim, J.-E.; Belmonte, J. A.; Kawaler, S. D.; Kepler, S. O.; Kanaan, A.; Giovannini, O.; Winget, D. E.; Watson, T. K.; Nather, R. E.; Clemens, J. C.; Provencal, J.; Dixson, J. S.; Yanagida, K.; Nitta Kleinman, A.; Montgomery, M.; Klumpe, E. W.; Bruvold, A.; O'Brien, M. S.; Hansen, C. J.; Grauer, A. D.; Bradley, P. A.; Wood, M. A.; Achilleos, N.; Jiang, S. Y.; Fu, J. N.; Marar, T. M. K.; Ashoka, B. N.; Meĭstas, E. G.; Chernyshev, A. V.; Mazeh, T.; Leibowitz, E.; Hemar, S.; Krzesiński, J.; Pajdosz, G.; Zoła, S.

    2002-01-01

    The pulsating PG 1159 planetary nebula central star RXJ 2117+3412 has been observed over three successive seasons of a multisite photometric campaign. The asteroseismological analysis of the data, based on the 37 identified l=1 modes among the 48 independent pulsation frequencies detected in the power spectrum, leads to the derivation of the rotational splitting, the period spacing and the mode trapping cycle and amplitude, from which a number of fundamental parameters can be deduced. The average rotation period is 1.16±0.05 days. The trend for the rotational splitting to decrease with increasing periods is incompatible with a solid body rotation. The total mass is 0.56+0.02-0.04 Msolar and the He-rich envelope mass fraction is in the range 0.013-0.078 M*. The luminosity derived from asteroseismology is log(L/Lsolar)= 4.05 +0.23-0.32 and the distance 760 +230-235 pc. At such a distance, the linear size of the planetary nebulae is 2.9±0.9 pc. The role of mass loss on the excitation mechanism and its consequence on the amplitude variations is discussed. Based on data obtained in observing time allocated by the Bernard Lyot Telescope, INSU/CNRS, France, the TCS at Teide Observatory, Tenerife, Spain, the INT and JKT Telescopes at Roque de Los Muchachos Observatory, La Palma, Spain, the Laboratorio Nacional de Astrofisica/CNPq, Brazil, the McDonal Observatory, Texas, USA, the Steward Observatory, Arizona, USA, the Mauna Kea Observatory, University of Hawaii, USA, the Mount Stromlo and Siding Spring Observatory, Australia, the Beijing Observatory, China, the Vainu Bappu Observatory, India, the Maidanak Observatory, Uzbekistan, the Wise Observatory, Israel, and the Suhora Observatory, Poland.

  9. The far-ultraviolet spectra of two hot PG 1159 stars

    NASA Astrophysics Data System (ADS)

    Werner, K.; Rauch, T.; Kruk, J. W.

    2016-09-01

    PG 1159 stars are hot, hydrogen-deficient (pre-) white dwarfs with atmospheres mainly composed of helium, carbon, and oxygen. The unusual surface chemistry is the result of a late helium-shell flash. Observed element abundances enable us to test stellar evolution models quantitatively with respect to their nucleosynthesis products formed near the helium-burning shell of the progenitor asymptotic giant branch stars. Because of the high effective temperatures (Teff), abundance determinations require ultraviolet spectroscopy and non-local thermodynamic equilibrium model atmosphere analyses. Up to now, we have presented results for the prototype of this spectral class and two cooler members (Teff in the range 85 000-140 000 K). Here we report on the results for two even hotter stars (PG 1520+525 and PG 1144+005, both with Teff = 150 000 K) which are the only two objects in this temperature-gravity region for which useful far-ultraviolet spectra are available, and revisit the prototype star. Previous results on the abundances of some species are confirmed, while results on others (Si, P, S) are revised. In particular, a solar abundance of sulphur is measured in contrast to earlier claims of a strong S deficiency that contradicted stellar evolution models. For the first time, we assess the abundances of Na, Al, and Cl with newly constructed non-LTE model atoms. Besides the main constituents (He, C, O), we determine the abundances (or upper limits) of N, F, Ne, Na, Al, Si, P, S, Cl, Ar, and Fe. Generally, good agreement with stellar models is found.

  10. The high-resolution spectrum of the pulsating, pre-white dwarf star PG 1159-035 (GW VIR)

    NASA Technical Reports Server (NTRS)

    Liebert, James; Wesemael, F.; Husfeld, D.; Wehrse, R.; Starrfield, S. G.

    1989-01-01

    High-resolution and low-resolution UV spectra and a high-resolution optical spectrum were obtained for PG 1159-035, revealing apparent photospheric absorption features with defined cores from N V 1240 A, N IV 1270 A, O V 1371 A, and C IV 1550 A. The photospheric velocity derived using all of these lines except for C IV is about +35 km/s. Equivalent-width measurements determined for all of the features may provide a tighter constraint on the photospheric temperature in a detailed model atmosphere analysis treating the CNO ions.

  11. Análisis astrosismológico de las estrellas PG 1159 pulsantes SDSS J0349-0059 y VV 47

    NASA Astrophysics Data System (ADS)

    Calcaferro, L. M.; Córsico, A. H.; Althaus, L. G.

    2016-08-01

    In this work we present the results of a detailed asteroseismological analysis performed for the two pulsating PG 1159 stars, SDSS J0349-0059 y VV 47, in order to estimate their mass and internal structure. PG 1159 stars are very hot compact objects with H-deficient atmospheres. These stars are associated to evolutionary stages previous to the white dwarf stars cooling phase, which in turn are the final evolutionary stage for the majority of all stars. Hence the analysis of PG 1159 stars is important to understand the processes that lead to formation of H-deficient white dwarf stars. This analysis is achieved by employing asteroseismological techniques focused on estimating the stellar mass and obtaining an asteroseismological model. The viability of this study is due to the fact that many of these stars exhibit multiperiodic variations of luminosity. Such is the case for the stars under study.

  12. On the Driving Mechanism and the Coexistence of Variable and Nonvariable Stars in the Domain of the Pulsating PG 1159 Stars

    NASA Astrophysics Data System (ADS)

    Quirion, P.-O.; Fontaine, G.; Brassard, P.

    2004-07-01

    We revisit the controversial question of the excitation of pulsation modes in models of PG 1159 stars that feature homogeneous envelopes with compositions comparable to those observed at the surface. We find, in agreement with some authors but contrary to others, that g-mode pulsations are naturally excited in such models and that there is no need to invoke composition gradients between the photosphere and the driving region in PG 1159 pulsators. We further find an excellent qualitative agreement between the range of predicted periods and the range of observed periods for all objects in our sample of pulsating stars, except for two models corresponding to the stars with the lowest surface gravities (central stars of planetary nebulae). We also address the problem of the coexistence of both variable and nonvariable PG 1159 stars in the same region of the logg-Teff diagram. We find a natural explanation for this cohabitation in terms of a dispersion in atmospheric parameters and in terms of a variation in surface composition from star to star. In particular, the most He-rich stars tend to be stable. We finally address the puzzling question of the existence of a correlation between pulsations and the presence of traces of nitrogen in the atmospheres of pulsating PG 1159 stars, a challenge that has remained unanswered so far.

  13. Evolution of Close Binary Systems

    SciTech Connect

    Yakut, K; Eggleton, P

    2005-01-24

    We collected data on the masses, radii, etc. of three classes of close binary stars: low-temperature contact binaries (LTCBs), near-contact binaries (NCBs), and detached close binaries (DCBs). They restrict themselves to systems where (1) both components are, at least arguably, near the Main Sequence, (2) the periods are less than a day, and (3) there is both spectroscopic and photometric analysis leading to reasonably reliable data. They discuss the possible evolutionary connections between these three classes, emphasizing the roles played by mass loss and angular momentum loss in rapidly-rotating cool stars.

  14. Close supermassive binary black holes.

    PubMed

    Gaskell, C Martin

    2010-01-01

    It has been proposed that when the peaks of the broad emission lines in active galactic nuclei (AGNs) are significantly blueshifted or redshifted from the systemic velocity of the host galaxy, this could be a consequence of orbital motion of a supermassive black-hole binary (SMBB). The AGN J1536+0441 ( = SDSS J153636.22+044127.0) has recently been proposed as an example of this phenomenon. It is proposed here instead that J1536+0441 is an example of line emission from a disk. If this is correct, the lack of clear optical spectral evidence for close SMBBs is significant, and argues either that the merging of close SMBBs is much faster than has generally been hitherto thought, or if the approach is slow, that when the separation of the binary is comparable to the size of the torus and broad-line region, the feeding of the black holes is disrupted. PMID:20054358

  15. Close supermassive binary black holes

    NASA Astrophysics Data System (ADS)

    Gaskell, C. Martin

    2010-01-01

    It has been proposed that when the peaks of the broad emission lines in active galactic nuclei (AGNs) are significantly blueshifted or redshifted from the systemic velocity of the host galaxy, this could be a consequence of orbital motion of a supermassive blackhole binary (SMB). The AGN J1536+0441 (=SDSS J153636.22+044127.0) has recently been proposed as an example of this phenomenon. It is proposed here instead that 1536+044 is an example of line emission from a disc. If this is correct, the lack of clear optical spectral evidence for close SMBs is significant and argues either that the merging of close SMBs is much faster than has generally been hitherto thought, or if the approach is slow, that when the separation of the binary is comparable to the size of the torus and broad-line region, the feeding of the black holes is disrupted.

  16. Close binary stars in globular clusters

    NASA Technical Reports Server (NTRS)

    Margon, Bruce

    1991-01-01

    Although close binary stars are thought theoretically to play a major role in globular cluster dynamics, virtually no non-degenerate close binaries are known in clusters. We review the status of observations in this area, and report on two new programs which are finally yielding candidate systems suitable for further study. One of the objects, a close eclipsing system in omega Cen, is also a big straggler, thus finally proving firm evidence that globular cluster blue stragglers really are binary stars.

  17. The evolution of close binary stars

    NASA Astrophysics Data System (ADS)

    Tutukov, A. V.; Cherepashchuk, A. M.

    2016-05-01

    A review of our current understanding of the physics and evolution of close binary stars with various masses under the influence of the nuclear evolution of their components and their magnetic stellar winds is presented. The role of gravitational-wave radiation by close binaries on their evolution and the loss of their orbital angular momentum is also considered. The final stages in the evolution of close binary systems are described. The review also notes the main remaining tasks related to studies of the physics and evolution of various classes of close binaries, including analyses of collisions of close binaries and supermassive black holes in galactic nuclei. Such a collision could lead to the capture of one of the components by the black hole and the acceleration of the remaining component to relativistic speeds.

  18. From wide to close binaries?

    NASA Astrophysics Data System (ADS)

    Eggleton, Peter P.

    The mechanisms by which the periods of wide binaries (mass 8 solar mass or less and period 10-3000 d) are lengthened or shortened are discussed, synthesizing the results of recent theoretical investigations. A system of nomenclature involving seven evolutionary states, three geometrical states, and 10 types of orbital-period evolution is developed and applied; classifications of 71 binaries are presented in a table along with the basic observational parameters. Evolutionary processes in wide binaries (single-star-type winds, magnetic braking with tidal friction, and companion-reinforced attrition), late case B systems, low-mass X-ray binaries, and triple systems are examined in detail, and possible evolutionary paths are shown in diagrams.

  19. Late type close binary system CM Dra

    NASA Astrophysics Data System (ADS)

    Kalomeni, Belinda

    2015-08-01

    In this study, we present new observations of the close binary system CM Dra. We analyzed all the available data of the system and estimated the physical parameters of the system stars highly accurately. Using the newly obtained parameters the distance of the system is determined to be 11.6 pc. A possible giant planet orbiting the close binary system has been detected. This orbital period would likely make it one of the longest known orbital period planet.

  20. Tidal evolution in close binary systems.

    NASA Technical Reports Server (NTRS)

    Kopal, Z.

    1972-01-01

    Mathematical outline of the theory of tidal evolution in close binary systems of secularly constant total momentum. Following a general outline of the problem the basic expressions for the energy and momenta of close binaries consisting of components of arbitrary internal structure are established, and the maximum and minimum values of the energy (kinetic and potential) which such systems can attain for a given amount of total momentum are investigated. These results are compared with the actual facts encountered in binaries with components whose internal structure (and, therefore, rotational momenta) are known from evidence furnished by the observed rates of apsidal advance. The results show that all such systems whether of detached or semidetached type - disclose that more than 99% of their total momenta are stored in the orbital momentum. The sum of the rotational momenta of the constituent components amounts to less than 1% of the total -a situation characteristic of a state close to the minimum energy for given total momentum.

  1. Saturated Activity: Very Close, Detached Binary Stars

    NASA Astrophysics Data System (ADS)

    Rucinski, Slavek M.

    It is proposed to obtain EUVE spectra of 4 close, synchronized, late-type binary stars with orbital/rotational periods shorter than 1.2 day, to study stellar coronal activity at very high, saturated levels. Among stars of spectral types between late-F to mid-K, only components of very close binary systems (and very rare young stars) can have such short rotational periods. Together with the EGO-1 and EGO-2 results for DH Leo and TZ CrB obtained by others, the spectra will be utilized in a comprehensive discussion of the saturated stellar activity, in relation to and in contrast with, the previously obtained by us spectra of the single, rapidly-rotating young star, AB Dor (P=0.51 day, EGO-1) and of two contact binary systems, 44i Boo (P=0.27 day) and VW Cep (P=0.28 day, EGO-2).

  2. Terrestrial Planet Formation Around Close Binary Stars

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Quintana, Elisa V.

    2003-01-01

    Most stars reside in multiple star systems; however, virtually all models of planetary growth have assumed an isolated single star. Numerical simulations of the collapse of molecular cloud cores to form binary stars suggest that disks will form within such systems. Observations indirectly suggest disk material around one or both components within young binary star systems. If planets form at the right places within such circumstellar disks, they can remain in stable orbits within the binary star systems for eons. We are simulating the late stages of growth of terrestrial planets around close binary stars, using a new, ultrafast, symplectic integrator that we have developed for this purpose. The sum of the masses of the two stars is one solar mass, and the initial disk of planetary embryos is the same as that used for simulating the late stages of terrestrial planet growth within our Solar System and in the Alpha Centauri wide binary star system. Giant planets &are included in the simulations, as they are in most simulations of the late stages of terrestrial planet accumulation in our Solar System. When the stars travel on a circular orbit with semimajor axis of up to 0.1 AU about their mutual center of mass, the planetary embryos grow into a system of terrestrial planets that is statistically identical to those formed about single stars, but a larger semimajor axis and/or a significantly eccentric binary orbit can lead to significantly more dynamically hot terrestrial planet systems.

  3. TeV emission from close binaries

    NASA Astrophysics Data System (ADS)

    Moskalenko, I. V.

    1995-05-01

    It is commonly accepted that candidates for very high energy γ-ray sources are neutron stars, binary systems, black holes etc. Close binary systems containing a normal hot star and a neutron star (or a black hole) form an important class of very high energy γ-ray sources. Such systems are variable in any region of the electromagnetic spectrum and they enable us to study various stages of stellar evolution, accretion processes, mechanisms of particle acceleration, etc. Phenomena connected with this class of very high energy γ-ray sources are discussed. Particular emphasis has been placed on the TeV energy region.

  4. Evolution of close binary systems: Observational aspects

    NASA Technical Reports Server (NTRS)

    Plavec, M. J.

    1981-01-01

    Detached close binary systems define the main sequence band satisfactorily, but very little is known about the masses of giants and supergiants. High dispersion international ultraviolet explorer satellite observations promise an improvement, since blue companions are now frequently found to late type supergiants. Mu Sagittaril and in particular Xi Aurigae are discussed in more detail. The barium star abundance anomaly appears to be due to mass transfer in interacting systems. The symbiotic stars are another type of binary systems containing late type giants; several possible models for the hotter star and for the type of interaction are discussed. The W Serpentis stars appear to be Algols in the rapid phase of mass transfer, but a possible link relating them to the symbiotics is also indicated. Evidence of hot circumstellar plasmas has now been found in several ordinary Algols; there may exist a smooth transition between very quiescent Algols and the W Serpentis stars. Beta Lyrae is discussed in the light of new spectrophotometric results.

  5. The Formation of Contact and Very Close Binaries

    SciTech Connect

    Kisseleva-Eggleton, L; Eggleton, P P

    2007-08-10

    We explore the possibility that all close binaries, i.e. those with periods {approx}< 3 d, including contact (W UMa) binaries, are produced from initially wider binaries (periods of say 10's of days) by the action of a triple companion through the medium of Kozai Cycles with Tidal Friction (KCTF).

  6. NONLINEAR TIDES IN CLOSE BINARY SYSTEMS

    SciTech Connect

    Weinberg, Nevin N.; Arras, Phil; Quataert, Eliot; Burkart, Josh

    2012-06-01

    We study the excitation and damping of tides in close binary systems, accounting for the leading-order nonlinear corrections to linear tidal theory. These nonlinear corrections include two distinct physical effects: three-mode nonlinear interactions, i.e., the redistribution of energy among stellar modes of oscillation, and nonlinear excitation of stellar normal modes by the time-varying gravitational potential of the companion. This paper, the first in a series, presents the formalism for studying nonlinear tides and studies the nonlinear stability of the linear tidal flow. Although the formalism we present is applicable to binaries containing stars, planets, and/or compact objects, we focus on non-rotating solar-type stars with stellar or planetary companions. Our primary results include the following: (1) The linear tidal solution almost universally used in studies of binary evolution is unstable over much of the parameter space in which it is employed. More specifically, resonantly excited internal gravity waves in solar-type stars are nonlinearly unstable to parametric resonance for companion masses M' {approx}> 10-100 M{sub Circled-Plus} at orbital periods P Almost-Equal-To 1-10 days. The nearly static 'equilibrium' tidal distortion is, however, stable to parametric resonance except for solar binaries with P {approx}< 2-5 days. (2) For companion masses larger than a few Jupiter masses, the dynamical tide causes short length scale waves to grow so rapidly that they must be treated as traveling waves, rather than standing waves. (3) We show that the global three-wave treatment of parametric instability typically used in the astrophysics literature does not yield the fastest-growing daughter modes or instability threshold in many cases. We find a form of parametric instability in which a single parent wave excites a very large number of daughter waves (N Almost-Equal-To 10{sup 3}[P/10 days] for a solar-type star) and drives them as a single coherent unit with

  7. Absolute dimensions of unevolved O type close binaries

    SciTech Connect

    Doom, C.; de Loore, C.

    1984-03-15

    A method is presented to derive the absolute dimensions of early-type detached binaries by combining the observed parameters with results of evolutionary computations. The method is used to obtain the absolute dimensions of nine close binaries. We find that most systems have an initial masss ratio near 1.

  8. White-light Flares on Close Binaries Observed with Kepler

    NASA Astrophysics Data System (ADS)

    Gao, Qing; Xin, Yu; Liu, Ji-Feng; Zhang, Xiao-Bin; Gao, Shuang

    2016-06-01

    Based on Kepler data, we present the results of a search for white light flares on 1049 close binaries. We identify 234 flare binaries, of which 6818 flares are detected. We compare the flare-binary fraction in different binary morphologies (“detachedness”). The result shows that the fractions in over-contact and ellipsoidal binaries are approximately 10%-20% lower than those in detached and semi-detached systems. We calculate the binary flare activity level (AL) of all the flare binaries, and discuss its variations along the orbital period (P orb) and rotation period (P rot, calculated for only detached binaries). We find that the AL increases with decreasing P orb or P rot, up to the critical values at P orb ˜ 3 days or P rot ˜ 1.5 days, and thereafter the AL starts decreasing no matter how fast the stars rotate. We examine the flaring rate as a function of orbital phase in two eclipsing binaries on which a large number of flares are detected. It appears that there is no correlation between flaring rate and orbital phase in these two binaries. In contrast, when we examine the function with 203 flares on 20 non-eclipse ellipsoidal binaries, bimodal distribution of amplitude-weighted flare numbers shows up at orbital phases 0.25 and 0.75. Such variation could be larger than what is expected from the cross section modification.

  9. ON THE LIKELIHOOD OF PLANET FORMATION IN CLOSE BINARIES

    SciTech Connect

    Jang-Condell, Hannah

    2015-02-01

    To date, several exoplanets have been discovered orbiting stars with close binary companions (a ≲ 30 AU). The fact that planets can form in these dynamically challenging environments implies that planet formation must be a robust process. The initial protoplanetary disks in these systems from which planets must form should be tidally truncated to radii of a few AU, which indicates that the efficiency of planet formation must be high. Here, we examine the truncation of circumstellar protoplanetary disks in close binary systems, studying how the likelihood of planet formation is affected over a range of disk parameters. If the semimajor axis of the binary is too small or its eccentricity is too high, the disk will have too little mass for planet formation to occur. However, we find that the stars in the binary systems known to have planets should have once hosted circumstellar disks that were capable of supporting planet formation despite their truncation. We present a way to characterize the feasibility of planet formation based on binary orbital parameters such as stellar mass, companion mass, eccentricity, and semimajor axis. Using this measure, we can quantify the robustness of planet formation in close binaries and better understand the overall efficiency of planet formation in general.

  10. Mass-transfer in close binary and their companions

    NASA Astrophysics Data System (ADS)

    Liao, Wenping; Qian, Shengbang; Zhu, Liying; Li, Linjia

    2016-07-01

    Secular and/or cyclical orbital period variations of close binaries can be derived by analyzing the (O-C) diagram. The secular variations are usually explained as mass transfer between components, while the most plausible explanation of the cyclic period changes is the light-travel time effect (LTTE) through the presence of a third body. Mass transfer and additional companions in close binary systems are important for understanding the formation and evolution of the systems. Here, UV light curves of several close binaries based on the Lunar-based Ultraviolet Telescope (LUT) observations are presented and analyzed with the Wilson-Devinney (W-D) method. Then, based on those light-curve solutions and new analysis of the orbital period variations, the multiplicity, geometrical structure and evolution state of targets are discussed.

  11. KIC 7177553: A Quadruple System of Two Close Binaries

    NASA Astrophysics Data System (ADS)

    Lehmann, H.; Borkovits, T.; Rappaport, S. A.; Ngo, H.; Mawet, D.; Csizmadia, Sz.; Forgács-Dajka, E.

    2016-03-01

    KIC 7177553 was observed by the Kepler satellite to be an eclipsing eccentric binary star system with an 18-day orbital period. Recently, an eclipse timing study of the Kepler binaries has revealed eclipse timing variations (ETVs) in this object with an amplitude of ˜100 s and an outer period of 529 days. The implied mass of the third body is that of a super-Jupiter, but below the mass of a brown dwarf. We therefore embarked on a radial velocity (RV) study of this binary to determine its system configuration and to check the hypothesis that it hosts a giant planet. From the RV measurements, it became immediately obvious that the same Kepler target contains another eccentric binary, this one with a 16.5-day orbital period. Direct imaging using adaptive optics reveals that the two binaries are separated by 0.″4 (˜167 AU) and have nearly the same magnitude (to within 2%). The close angular proximity of the two binaries and very similar γ velocities strongly suggest that KIC 7177553 is one of the rare SB4 systems consisting of two eccentric binaries where at least one system is eclipsing. Both systems consist of slowly rotating, nonevolved, solar-like stars of comparable masses. From the orbital separation and the small difference in γ velocity, we infer that the period of the outer orbit most likely lies in the range of 1000-3000 yr. New images taken over the next few years, as well as the high-precision astrometry of the Gaia satellite mission, will allow us to set much narrower constraints on the system geometry. Finally, we note that the observed ETVs in the Kepler data cannot be produced by the second binary. Further spectroscopic observations on a longer timescale will be required to prove the existence of the massive planet.

  12. Kitt Peak Speckle Interferometry of Close Visual Binary Stars (Abstract)

    NASA Astrophysics Data System (ADS)

    Gener, R.; Rowe, D.; Smith, T. C.; Teiche, A.; Harshaw, R.; Wallace, D.; Weise, E.; Wiley, E.; Boyce, G.; Boyce, P.; Branston, D.; Chaney, K.; Clark, R. K.; Estrada, C.; Estrada, R.; Frey, T.; Green, W. L.; Haurberg, N.; Jones, G.; Kenney, J.; Loftin, S.; McGieson, I.; Patel, R.; Plummer, J.; Ridgely, J.; Trueblood, M.; Westergren, D.; Wren, P.

    2014-12-01

    (Abstract only) Speckle interferometry can be used to overcome normal seeing limitations by taking many very short exposures at high magnification and analyzing the resulting speckles to obtain the position angles and separations of close binary stars. A typical speckle observation of a close binary consists of 1,000 images, each 20 milliseconds in duration. The images are stored as a multi-plane FITS cube. A portable speckle interferometry system that features an electron-multiplying CCD camera was used by the authors during two week-long observing runs on the 2.1-meter telescope at Kitt Peak National Observatory to obtain some 1,000 data cubes of close binaries selected from a dozen different research programs. Many hundreds of single reference stars were also observed and used in deconvolution to remove undesirable atmospheric and telescope optical effects. The database of well over one million images was reduced with the Speckle Interferometry Tool of platesolve3. A few sample results are provided. During the second Kitt Peak run, the McMath-Pierce 1.6- and 0.8-meter solar telescopes were evaluated for nighttime speckle interferometry, while the 0.8-meter Coude feed was used to obtain differential radial velocities of short arc binaries.

  13. Five-color band ultraviolet photometry of fourteen close binaries

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Mccluskey, G. E.; Wu, C.-C.

    1981-01-01

    Photometric observations obtained with the Astronomical Netherlands Satellite in five ultraviolet wavelength regions for 14 close binaries are presented. Strong excess far-ultraviolet flux is detected in four objects. The binaries TT Hya, RX Cas, and SX Cas exhibit a pronounced excess of far-ultraviolet flux, which is thought to be the result of mass transfer phenomena in these systems. Observations of the binary R Ara show very peculair variations; its far ultraviolet flux at 1550 A brightened by 0.4 mag between phases 0.7 and 0.8, while its near ultraviolet flux at 3300 A decreased by 0.5 mag over this same half-day interval. The A0 II-III component in the system RZ Sct is seen to dominate the ultraviolet spectrum.

  14. Hydrodynamic Simulations of Close and Contact Binary Systems using Bipolytropes

    NASA Astrophysics Data System (ADS)

    Kadam, Kundan

    2016-01-01

    I will present the results of hydrodynamic simulations of close and contact bipolytropic binary systems. This project is motivated by the peculiar case of the red nova, V1309 Sco, which is indeed a merger of a contact binary. Both the stars are believed to have evolved off the main sequence by the time of the merger and possess a small helium core. In order to represent the binary accurately, I need a core-envelope structure for both the stars. I have achieved this using bipolytropes or composite polytropes. For the simulations, I use an explicit 3D Eulerian hydrodynamics code in cylindrical coordinates. I will discuss the evolution and merger scenarios of systems with different mass ratios and core mass fractions as well as the effects due to the treatment of the adiabatic exponent.

  15. A Hidden Population of Hot Subdwarf Stars in Close Binaries

    NASA Astrophysics Data System (ADS)

    Wade, Richard A.; Clausen, Drew R.; Kopparapu, Ravi Kumar; O'Shaughnessy, Richard; Stark, M. A.; Walentosky, M. J.

    2010-12-01

    Observations to date preferentially find Galactic hot subdwarf (sdB/sdO) stars in binaries when the subdwarfs are more luminous than their relatively faint companions (G/K/M dwarfs, white dwarfs). As suggested by Han et al. [1], this selection bias may distort our perspective of the evolutionary channels that form hot subdwarfs in the galactic disk. A predicted and possibly more numerous population of binaries features a lower-mass, lower-luminosity, longer-lived hot subdwarf hiding in the glare from its companion: the subdwarf+A/early F binaries. Such systems may arise when mass transfer is initiated in the Hertzsprung gap; the A/F companion in some cases was ``created'' from a lower-mass star (i.e., it would be a blue straggler if seen in a cluster). A survey is underway at Penn State to identify hot subdwarfs paired with F stars, determine their properties, and establish their space density. The project makes use of ground and space archival data to identify these systems (from their UV excesses) and new spectroscopic observations to determine their orbital periods and other properties. Successful characterization of this group of close binaries should help to challenge, calibrate, or refine models of binary star evolution that are used in population synthesis studies, including the relative importance of the RLOF and common-envelope channels for the formation of hot subdwarfs. The motivation, methodology, and status of this search for hidden hot subdwarfs are presented in this contribution.

  16. CLOSE BINARIES WITH INFRARED EXCESS: DESTROYERS OF WORLDS?

    SciTech Connect

    Matranga, M.; Drake, J. J.; Kashyap, V. L.; Marengo, M.; Kuchner, M. J.

    2010-09-10

    We present the results of a Spitzer photometric investigation into the IR excesses of close binary systems. In a sample of 10 objects, excesses in Infrared Array Camera and MIPS24 bands implying the presence of warm dust are found for 3. For two objects, we do not find excesses reported in earlier IRAS studies. We discuss the results in the context of the scenario suggested by Rhee and co-workers, in which warm dust is continuously created by destructive collisions between planetary bodies. A simple numerical model for the steady-state distribution of dust in one IR excess system shows a central clearing of radius 0.22 AU caused by dynamical perturbations from the binary star. This is consistent with the size of the central clearing derived from the Spitzer spectral energy distribution. We conclude that close binaries could be efficient 'destroyers of worlds' and lead to destabilization of the orbits of their planetary progeny by magnetically driven angular momentum loss and secular shrinkage of the binary separation.

  17. RADIAL VELOCITY STUDIES OF CLOSE BINARY STARS. XV

    SciTech Connect

    Pribulla, Theodor; Rucinski, Slavek M.; Blake, R. M.; Lu, Wenxian; Thomson, J. R.; DeBond, Heide; Karmo, Toomas; De Ridder, Archie; Ogloza, Waldemar; Stachowski, Greg; Siwak, Michal E-mail: rucinski@astro.utoronto.ca E-mail: karmo@astro.utoronto.ca E-mail: ogloza@ap.krakow.pl E-mail: siwak@oa.uj.edu.pl

    2009-03-15

    Radial velocity (RV) measurements and sine curve fits to the orbital RV variations are presented for the last eight close binary systems analyzed in the same way as in the previous papers of this series: QX And, DY Cet, MR Del, HI Dra, DD Mon, V868 Mon, ER Ori, and Y Sex. For another seven systems (TT Cet, AA Cet, CW Lyn, V563 Lyr, CW Sge, LV Vir, and MW Vir), phase coverage is insufficient to provide reliable orbits but RVs of individual components were measured. Observations of a few complicated systems observed throughout the David Dunlap Observatory (DDO) close binary program are also presented; among them is an especially interesting multiple system V857 Her which-in addition to the contact binary-very probably contains one or more subdwarf components of much earlier spectral type. All suspected binaries which were found to be most probably pulsating stars are briefly discussed in terms of mean RVs and projected rotation velocities (vsin i) as well as spectral-type estimates. In two of them, CU CVn and V752 Mon, the broadening functions show a clear presence of nonradial pulsations. The previously missing spectral types for Paper I are given here in addition to such estimates for most of the program stars of this paper.

  18. Massive close binaries with early-type components

    NASA Astrophysics Data System (ADS)

    Polushina, T. S.

    A brief review of the study of massive close binaries system with the hot components carried out in Kourovka astronomical observatory is presented including such systems as CC Cas, SZ Cam, UU Cas, V368 Cas, BH Cen, SV Cen, LY Aur, V701 Sco. An attempt to explain the results of observations by the presence of circumstellar matter has been made. Some estimates of the circumstellar matter parameters are obtained.

  19. Evolution of Very Close Binaries of Low Mass

    SciTech Connect

    Eggleton, P

    2009-07-17

    Binaries of low total mass (say 1-3 M{sub {circle_dot}}) and very short period (say {approx}< 4 d) are subject to a number of evolutionary processes, such as nuclear evolution, Roche-Lobe overflow, mass loss by stellar wind enhanced by rapid rotation, angular momentum loss by stellar wind with magnetic braking and tidal friction, mass transfer in contact (potentially in either direction), and heat transport from one component to the other during contact. Unfortunately all of these phenomena can be expected to occur on something like the same timescale. This makes it especially difficult to tie a particular system to a particular set of evolutionary processes. Theory suggests that very close binaries should appear in four morphological forms: detached binaries, semidetached binaries in which the more massive component is the one that fills its Roche lobe (reverse Algols), semidetached binaries in which the less massive component is the one that fills its Roche lobe (normal Algols), and contact, or, as some would say, overcontact binaries, where both components overfill their Roche lobes up to the same equipotential surface. This is not to say that perhaps some other configuration may be important, but I am not sure that any has yet been put forward that is incontrovertible. I have developed an evolutionary code in which the two components are solved simultaneously, and subject in principle to all six of the processes in the first paragraph. All four morphological forms are achievable by the code, as the physics demands. The code is still preliminary, partly at least because of the difficulty of quantifying all six processes. I will illustrate some possibly peculiar evolutionary scenarios that can emerge; but I will mainly argue, on the basis of observed data from a variety of systems, that it is indeed necessary to include all these processes, and not, for example, to ignore mass loss by stellar wind by claiming that it cannot be strong enough to be significant.

  20. Interactive stars - Normal and compact stars in close binaries

    NASA Technical Reports Server (NTRS)

    Swank, J. H.

    1990-01-01

    The missions planned for the 1990's will greatly expand the knowledge of close binary systems and the physical phenomena that can be studied in a member of a close binary, from stellar active regions to the highest density black hole candidates known. These systems and the phenomena are reviewed with reference to major outstanding questions, the expected capability to answer them, and the expansion of capability that would be necessary. A 'super' XMM or LAMAR experiment with larger area, but similar moderate energy resolution and moderate spatial resolution, could detect 0.1 millisecond bursts from Cyg X-1 and 1 millisecond bursts in quiescent black hole candidates, measure Doppler and gravitational energy shifts in the iron line features for black holes and neutron stars. It would also identify these objects in galaxies a few Mpc away and open the way for evolution studies. A somewhat less ambitious goal would be high energy resolution of about the area of LAMAR to make full use of the information in the emission lines in both normal and compact binaries.

  1. NEAs' Binaries and Planetary Close Encounters -Stability and Lifetime

    NASA Astrophysics Data System (ADS)

    Araujo, Rosana; Winter, O.

    2013-05-01

    Abstract (2,250 Maximum Characters): In the present work we considered the effects of close encounters, suffered by hypothetical NEAs binaries, with Earth, Mercury and Venus, in order to determine the stability of their satellites as a function of the encounter conditions. In addition, knowing the conditions that leads to the loss (by ejection or collisions) of the most internal satellites, we are able to estimate the frequency of such encounters, and thus, determine the expected lifetime of the NEAs binaries. The methodology consisted on numerically simulate a system composed by the Sun, the planets of the Solar System, and a sample of 2100 NEAs, for a period of 10 Myr (predict NEAs' lifetime). All close encounters with the planets closer than 100 planet's radius were registered. The next step consisted on simulate a representative sample of those registered close encounters, through numerical integration, considering the planet, the asteroid that perform the close encounter, and a cloud of satellites around the asteroid. The largest radial distance for which all the satellites survive (no collision or ejection) was defined as the critical radius - Rc, given as a function of the encounter parameters (relative velocity and impact parameter). For the Earth, we found that the close encounters with impact parameter and relative velocity capable to remove the most internal satellites of the NEAs (Rc < 5 km), are very frequent. We found that 93% of the asteroids of the group Atens suffer an encounter within this limit in 10 Myrs, and that 50% of these encounters happen in approximately 330.000 years. For the Apollos we found that 60% of the asteroids suffer such encounters, and that 50% of then happen in approximately 700.000 years. Such results indicate that, in fact, the lifetime of the binaries is strongly influencied by the planetary close encounters, proving to be significantly shorter than the predicted lifetime of the NEAs. The contribution of the planets Mercury

  2. CLOSE STELLAR BINARY SYSTEMS BY GRAZING ENVELOPE EVOLUTION

    SciTech Connect

    Soker, Noam

    2015-02-20

    I suggest a spiral-in process in which a stellar companion grazes the envelope of a giant star while both the orbital separation and the giant radius shrink simultaneously, forming a close binary system. The binary system might be viewed as evolving in a constant state of 'just entering a common envelope (CE) phase.' In cases where this process takes place, it can be an alternative to CE evolution where the secondary star is immersed in the giant's envelope. Grazing envelope evolution (GEE) is made possible only if the companion manages to accrete mass at a high rate and launches jets that remove the outskirts of the giant envelope, hence preventing the formation of a CE. The high accretion rate is made possible by the accretion disk launching jets which efficiently carry the excess angular momentum and energy from the accreted mass. The orbital decay itself is caused by the gravitational interaction of the secondary star with the envelope inward of its orbit, i.e., dynamical friction (gravitational tide). Mass loss through the second Lagrangian point can carry additional angular momentum and envelope mass. The GEE lasts for tens to hundreds of years. The high accretion rate, with peaks lasting from months to years, might lead to a bright object referred to as the intermediate luminosity optical transient (Red Novae; Red Transients). A bipolar nebula and/or equatorial ring are formed around the binary remnant.

  3. Faint carbon stars from the evolution of close binaries.

    NASA Astrophysics Data System (ADS)

    Frantsman, J.

    1997-03-01

    The assumption that faint carbon stars in the Magellanic Clouds are on the early asymptotic giant branch (E-AGB) evolutionary stage, is examined using population simulation techniques. It is assumed that these stars are formed as a result of the mass transfer in close binary systems while the primary is a carbon star on the thermally-pulsing AGB (TP-AGB) stage. The populations of carbon stars resulting from both single-star evolution and mass transfer in close binary systems have been calculated. For the heavy element abundance by mass Z=0.002, the expected amount of E-AGB carbon stars is comparable with the amount of those in the TP-AGB stage. The theoretically obtained and observed luminosity functions of E-AGB carbon stars are similar. Examples illustrating the importance of correct identification of star's evolutionary stage for the interpretation of observations are given. The ignorance of the fact that AGB consists of two stages of the evolution leads to wrong cluster ages resulting from the luminosities of AGB stars.

  4. Near-Contact Binaries (NCB): Close Binary Systems in a Key Evolutionary Stage

    NASA Astrophysics Data System (ADS)

    Zhu, L. Y.; Qian, S. B.

    2007-08-01

    Short-period eclipsing binary systems with EB-type light variations are interesting objects for understanding the evolutionary changes undergone by close binaries. As investigated by many authors (Kalużny, J., Yamasaki, A., Zhai, D. S, Zhang, X. B Hilditch, R. W., McFarlane, T. M, King, D. J, Shaw, J. S., Samec, R. G., Niarchos, P. G., Oh, Kyu-Dong. etc ), a majority of them belong to an important subclass of close binaries called near-contact binaries (NCBs). According to the geometric definition of this subclass, NCBs actually comprise semi-detached, marginal-contact, and marginal-detached systems. They can be in the intermediate stage between detached or semi-detached state and contact state. Therefore, NCBs are the important observational targets which may be lying in key evolutionary states. In this paper, we observed and investigated several NCBs (BL And, GW Tau, RU UMi, GSC3658-0076, UU Lyn, AS Ser, IR Cas, EP Aur). Our results show that the orbital periods of BL And, GW Tau, RU UMi and UU Lyn are decreasing while that of IR Cas is decreasing and oscillating. The mechanisms that could explain the period variations are discussed. Combining the photometric solutions with period variations of these systems, we divide them into four types: BL And is a semi-detached system with the lobe filling primary, RU UMi and EP Aur are the semi-detached system with the lobe filling secondary, GW Tau, UU Lyn and AS Ser are the marginal contact system while GSC3658-0076 is the marginal detached system. Finally, the evolutionary stage of each system is discussed and some statistical relations of NCBs are presented.

  5. Close PMS Binaries Evolution - Hints for Planet Formation

    NASA Astrophysics Data System (ADS)

    Gomez De Castro, Ana; Bisikalo, Dmitry; Sytov, Alexey; Ustamujic, Sabina

    2016-07-01

    In close PMS systems, accretion disks can either take up or release angular momentum and the details of evolution depend on the mass ratio between the two stars and on the orbit eccentricity (Artymowicz & Lubow, 1994; Bate & Bonnell, 1997; Hanawa et al., 2010, de Val Borro et al., 2011, Shi et al., 2012). Highly eccentric orbits favour the formation of spiral waves within the inner disk that do channel the flow as the accreting gas streams onto each star. In this framework, PMS binaries represent a special kind of interacting binaries where the circumbinary disk mediates in the star-star interaction as a continuous supply of angular momentum (and matter) to the system. The most general configuration consists of a circumbinary disk with inner radius about three times the semimajor axis and a variable distribution of matter within the hole. Circumstellar structures similar to disks are occasionally formed around the stars chanelling the accretion flow. The ultraviolet radiation generated by the stars and the accretion shocks can be used to map the distribution of matter in the hole and the CS environment (Gómez de Castro et al. 2016). In this contribution we describe monitoring strategies to map the variable distribution of CS matter in these systems and its extension to the study of exoplanetary systems hosting hot Jupiters.

  6. A photometric study of the close binary Delta Orionis A

    NASA Astrophysics Data System (ADS)

    Koch, R. H.; Hrivnak, B. J.

    1981-08-01

    Green and blue photoelectric light curves show the historical intrinsic variability of the Delta Ori A close binary superposed on the interaction and eclipse effects. There is a considerable measure of agreement between spectrographic and photometric determinations of the rate of apsidal advance. The determinacy of orbital eccentricity, however, is confused because few minima of indifferent precision exist to check the spectrographic value. No physical mechanism can be found to account for a possible diminution of orbital eccentricity, and this is probably best attributed to unrecognized complications of at least one of the existing light curves. After numerous trials, a less-than-perfect theoretical representation of the light curve was achieved and shows the system to be detached. The absolute stellar parameters make clear that both components have evolved substantially. A mean stellar structure constant k2 is derived but cannot be compared usefully to existing theoretical values. The importance of the recently discovered visual companion, hz 42, is emphasized.

  7. Irradiation effects in close binaries in an electron scattering medium

    NASA Astrophysics Data System (ADS)

    Varghese, B. A.; Srinivasa Rao, M.

    2016-03-01

    In a close binary system, the effects of irradiation are studied from an extended surface of the secondary component on the atmosphere of the primary. Primary and the secondary components are assumed to have equal radii and the thickness of the atmosphere is assumed to be twice that of the stellar radius of the primary component. Self radiation of the primary component (Ss) is calculated through a numerical solution of line transfer equation in the comoving frame with Compton broadening due to electron scattering. The solution is developed through discrete space theory to deal with different velocities in a spherically expanding medium. The irradiation from the secondary (SI) is calculated using one dimensional rod model. It is assumed to be one, five and ten times the self radiation. The total source function (S=Ss+SI) is the sum of the source functions due to self radiation and that due to irradiation. The line fluxes are computed along the line of sight by using the above source functions. Line profiles are also computed for different line center optical depths along the line of sight of the observer at infinity.

  8. Properties of the components in close T Tauri binary systems

    NASA Astrophysics Data System (ADS)

    Woitas, Jens; Leinert, Christoph

    Using near-infrared speckle-interferometry we have obtained resolved JHK-photometry for the components of T Tauri binary systems. By placing the components into a color-color diagram we identify some unusually red objects that are candidates for infrared companions or substellar objects. We place a subsample that consists of the components of 17 WTTS systems (where no significant circumstellar excess emission is expected) into a color-magnitude diagram and show that in almost all of these systems the components are coeval within the uncertainties. Particularly this is the case for the triple system HBC 358. We use the J-magnitude as an indicator for the stellar luminosity and assign the optical spectral type of the system to the primary. Together with the previously justified assumption that all components are coeval we can place them independently into the HRD and derive their masses by comparison with theoretical pre-main sequence evolutionary tracks. The results are the following: The distribution of mass ratios is flat and is neither a function of the primary's mass nor the components' projected separation. Comparison of these results with predictions of theoretical multiple star formation models suggests that most of the systems have formed by fragmentation during protostellar collapse. From relative positions of the components in 34 systems at different epochs we derive their relative velocities and show that in most close systems orbital motion can be proved. The analysis of this orbital motion leads to an empirical mass estimate for T Tauri-stars which is larger than the masses one would expect from the HRD.

  9. Close Binaries in the 21st Century: New Opportunities and Challenges

    NASA Astrophysics Data System (ADS)

    Giménez, A.; Guinan, E.; Niarchos, P.; Rucinski, S.

    2006-12-01

    An International Conference entitled "Close Binaries in the 21st Century: New Opportunities and Challenges", was held in Syros island, Greece, from 27 to 30 June, 2005. There are many binary star systems whose components are so close together, that they interact in various ways. Stars in such systems do not pass through all stages of their evolution independently of each other; in fact their evolutionary path is significantly affected by their companions. Processes of interaction include gravitational effects, mutual irradiation, mass exchange, mass loss from the system, phenomena of extended atmospheres, semi-transparent atmospheric clouds, variable thickness disks and gas streams. The zoo of Close Binary Systems includes: Close Eclipsing Binaries (Detached, Semi-detached, Contact), High and Low-Mass X-ray Binaries, Cataclysmic Variables, RS CVn systems, Pulsar Binaries and Symbiotic Stars. The study of these binaries triggered the development of new branches of astrophysics dealing with the structure and evolution of close binaries and the interaction effects displayed by these exciting objects. Close Binaries are classic examples of the fundamental contribution that stellar astrophysics makes to our general understanding of physical processes in the universe. Ground-based and space surveys will discover many new close binaries, which were previously unknown. In the future, new approaches will also be possible with highly efficient photometric searches looking for very shallow eclipses, such as those produced by Earth-like extra-solar planets. Contributions to this conference covered the latest achievements in the field and reflected the state of the art of the dynamically evolving area of binary star research. Link: http://www.springer.com/east/home/generic/search/results?SGWID=5-40109-22-173660047-0

  10. A model for binary-binary close encounters and collisions from a dynamical point of view

    NASA Astrophysics Data System (ADS)

    Alvarez-Ramírez, Martha; Medina, Mario

    2014-01-01

    The goal of this paper is to provide a model for binary-binary interactions in star clusters, which is based on simultaneous binary collision of a special case of the one-dimensional 4-body problem where four masses move symmetrically about the center of mass. From the theoretical point of view, the singularity due to binary collisions between point masses can be handled by means of regularization theory. Our main tool is a change of coordinates due to McGehee by which we blow-up the singular set associated to total collision and replace it with an invariant manifold which includes binary and simultaneous binary collisions, and then gain a complete picture of the local behavior of the solutions near to total collision via the homothetic orbit.

  11. Kepler eclipsing binary stars. IV. Precise eclipse times for close binaries and identification of candidate three-body systems

    SciTech Connect

    Conroy, Kyle E.; Stassun, Keivan G.; Prša, Andrej; Orosz, Jerome A.; Welsh, William F.; Fabrycky, Daniel C.

    2014-02-01

    We present a catalog of precise eclipse times and analysis of third-body signals among 1279 close binaries in the latest Kepler Eclipsing Binary Catalog. For these short-period binaries, Kepler's 30 minute exposure time causes significant smearing of light curves. In addition, common astrophysical phenomena such as chromospheric activity, as well as imperfections in the light curve detrending process, can create systematic artifacts that may produce fictitious signals in the eclipse timings. We present a method to measure precise eclipse times in the presence of distorted light curves, such as in contact and near-contact binaries which exhibit continuously changing light levels in and out of eclipse. We identify 236 systems for which we find a timing variation signal compatible with the presence of a third body. These are modeled for the light travel time effect and the basic properties of the third body are derived. This study complements J. A. Orosz et al. (in preparation), which focuses on eclipse timing variations of longer period binaries with flat out-of-eclipse regions. Together, these two papers provide comprehensive eclipse timings for all binaries in the Kepler Eclipsing Binary Catalog, as an ongoing resource freely accessible online to the community.

  12. Doublet 2800 MgII in close binary systems

    NASA Technical Reports Server (NTRS)

    Gurzadian, G. A.; Perez, M.

    1991-01-01

    The origin of the intercomponent ultraviolet emission from binary radio stars is discussed following an examination of observed emission parameters. Observations are used to consider four arguments which suggest that the Mg emission originates in the space between the components of the binary and not in the chromosphere. Parameters examined include the ratio of Mg emission to that of other binaries, the direct variation of emission with brightness strength, the derivation and nature of the radial velocity, and comparisons of absolute luminosities. Emission (A) and absorption (B) streams or clouds generate the emission, and the observed wavelength distortions are caused by B. An examination of the nature of the emission yields both qualitative and quantitative criteria, including the notion of weak ionization of the hydrogen atoms in B clouds relative to the ionization in A clouds.

  13. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, Scott R.; Christophorou, Loucas G.

    1990-01-01

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

  14. A catalogue of potentially bright close binary gravitational wave sources

    NASA Technical Reports Server (NTRS)

    Webbink, Ronald F.

    1985-01-01

    This is a current print-out of results of a survey, undertaken in the spring of 1985, to identify those known binary stars which might produce significant gravitational wave amplitudes at earth, either dimensionless strain amplitudes exceeding a threshold h = 10(exp -21), or energy fluxes exceeding F = 10(exp -12) erg cm(exp -2) s(exp -1). All real or putative binaries brighter than a certain limiting magnitude (calculated as a function of primary spectral type, orbital period, orbital eccentricity, and bandpass) are included. All double degenerate binaries and Wolf-Rayet binaries with known or suspected orbital periods have also been included. The catalog consists of two parts: a listing of objects in ascending order of Right Ascension (Equinox B1950), followed by an index, listing of objects by identification number according to all major stellar catalogs. The object listing is a print-out of the spreadsheets on which the catalog is currently maintained. It should be noted that the use of this spreadsheet program imposes some limitations on the display of entries. Text entries which exceed the cell size may appear in truncated form, or may run into adjacent columns. Greek characters are not available; they are represented here by the first two or three letters of their Roman names, the first letter appearing as a capital or lower-case letter according to whether the capital or lower-case Greek character is represented. Neither superscripts nor subscripts are available; they appear here in normal position and type-face. The index provides the Right Ascension and Declination of objects sorted by catalogue number.

  15. Searching Planets Around Some Selected Eclipsing Close Binary Stars Systems

    NASA Astrophysics Data System (ADS)

    Nasiroglu, Ilham; Slowikowska, Agnieszka; Krzeszowski, Krzysztof; Zejmo, M. Michal; Er, Hüseyin; Goździewski, Krzysztof; Zola, Stanislaw; Koziel-Wierzbowska, Dorota; Debski, Bartholomew; Ogloza, Waldemar; Drozdz, Marek

    2016-07-01

    We present updated O-C diagrams of selected short period eclipsing binaries observed since 2009 with the T100 Telescope at the TUBITAK National Observatory (Antalya, Turkey), the T60 Telescope at the Adiyaman University Observatory (Adiyaman, Turkey), the 60cm at the Mt. Suhora Observatory of the Pedagogical University (Poland) and the 50cm Cassegrain telescope at the Fort Skala Astronomical Observatory of the Jagiellonian University in Krakow, Poland. All four telescopes are equipped with sensitive, back-illuminated CCD cameras and sets of wide band filters. One of the targets in our sample is a post-common envelope eclipsing binary NSVS 14256825. We collected more than 50 new eclipses for this system that together with the literature data gives more than 120 eclipse timings over the time span of 8.5 years. The obtained O-C diagram shows quasi-periodic variations that can be well explained by the existence of the third body on Jupiter-like orbit. We also present new results indicating a possible light time travel effect inferred from the O-C diagrams of two other binary systems: HU Aqr and V470 Cam.

  16. A Search for Close Red Dwarf-White Dwarf Binaries

    NASA Astrophysics Data System (ADS)

    Boyd, Mark R.; Henry, Todd J.; Subasavage, John P.

    2011-08-01

    We propose to observe 59 objects suspected to be red dwarf-white dwarf (RD-WD) binaries with separations < 3 arcsec using the CTIO 1.0m. Our goals are to use images of these objects to both resolve the systems and to obtain accurate BVRI photometry. The systems have been selected based on positions in three different color-color plots using SuperCOSMOS BRI plate photometry and 2MASS JHK photometry in accordance with the positions of known RD-WD binaries. This effort will identify candidates for detailed observations as part of the RECONS astrometric program on the CTIO 0.9m to yield accurate parallaxes and photocentric orbits. The parallaxes will then be used to determine the ages of the systems from WD cooling curves, and the orbits will eventually be used to measure dynamical masses. Ultimately, we aim to increase significantly the number of dynamical masses for white dwarfs because currently only three have been determined to 5% accuracy. The first observational step outlined here will allow us to identify appropriate systems for long-term work. This 1.0m project is likely to become the undergraduate senior thesis work of the PI.

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

    NASA Astrophysics Data System (ADS)

    Kraus, Adam L.; Ireland, Michael J.; Huber, Daniel; Mann, Andrew W.; Dupuy, Trent J.

    2016-07-01

    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 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 <5 au, showing that planets might form in these dynamically active environments. However, the full distribution of projected separations for our planet-host sample more broadly reveals a deep paucity of binary companions at solar-system scales. For a field binary population, we should have found 58 binary companions with projected separation ρ < 50 au and mass ratio q > 0.4 we instead only found 23 companions (a 4.6σ 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}-23+59 au, the planet occurrence rate in binary systems is only {S}{bin}={0.34}-0.15+0.14 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.

  18. MILLIONS OF MULTIPLES: DETECTING AND CHARACTERIZING CLOSE-SEPARATION BINARY SYSTEMS IN SYNOPTIC SKY SURVEYS

    SciTech Connect

    Terziev, Emil; Law, Nicholas M.; Arcavi, Iair; Baranec, Christoph; Bui, Khanh; Dekany, Richard G.; Kulkarni, S. R.; Riddle, Reed; Tendulkar, Shriharsh P.; Bloom, Joshua S.; Burse, Mahesh P.; Chorida, Pravin; Das, H. K.; Punnadi, Sujit; Ramaprakash, A. N.; Kraus, Adam L.; Nugent, Peter; Ofek, Eran O.; Sullivan, Mark

    2013-06-01

    The direct detection of binary systems in wide-field surveys is limited by the size of the stars' point-spread functions (PSFs). A search for elongated objects can find closer companions, but is limited by the precision to which the PSF shape can be calibrated for individual stars. Based on a technique from weak-lensing analysis, we have developed the BinaryFinder algorithm to search for close binaries by using precision measurements of PSF ellipticity across wide-field survey images. We show that the algorithm is capable of reliably detecting binary systems down to Almost-Equal-To 1/5 of the seeing limit, and can directly measure the systems' position angles, separations, and contrast ratios. To verify the algorithm's performance we evaluated 100,000 objects in Palomar Transient Factory (PTF) wide-field-survey data for signs of binarity, and then used the Robo-AO robotic laser adaptive optics system to verify the parameters of 44 high-confidence targets. We show that BinaryFinder correctly predicts the presence of close companions with a <11% false-positive rate, measures the detected binaries' position angles within 1 Degree-Sign to 4 Degree-Sign (depending on signal-to-noise ratio and separation), and separations within 25%, and weakly constrains their contrast ratios. When applied to the full PTF data set, we estimate that BinaryFinder will discover and characterize {approx}450,000 physically associated binary systems with separations <2 arcsec and magnitudes brighter than m{sub R} = 18. New wide-field synoptic surveys with high sensitivity and sub-arcsecond angular resolution, such as LSST, will allow BinaryFinder to reliably detect millions of very faint binary systems with separations as small as 0.1 arcsec.

  19. Millions of Multiples: Detecting and Characterizing Close-separation Binary Systems in Synoptic Sky Surveys

    NASA Astrophysics Data System (ADS)

    Terziev, Emil; Law, Nicholas M.; Arcavi, Iair; Baranec, Christoph; Bloom, Joshua S.; Bui, Khanh; Burse, Mahesh P.; Chorida, Pravin; Das, H. K.; Dekany, Richard G.; Kraus, Adam L.; Kulkarni, S. R.; Nugent, Peter; Ofek, Eran O.; Punnadi, Sujit; Ramaprakash, A. N.; Riddle, Reed; Sullivan, Mark; Tendulkar, Shriharsh P.

    2013-06-01

    The direct detection of binary systems in wide-field surveys is limited by the size of the stars' point-spread functions (PSFs). A search for elongated objects can find closer companions, but is limited by the precision to which the PSF shape can be calibrated for individual stars. Based on a technique from weak-lensing analysis, we have developed the BinaryFinder algorithm to search for close binaries by using precision measurements of PSF ellipticity across wide-field survey images. We show that the algorithm is capable of reliably detecting binary systems down to ≈1/5 of the seeing limit, and can directly measure the systems' position angles, separations, and contrast ratios. To verify the algorithm's performance we evaluated 100,000 objects in Palomar Transient Factory (PTF) wide-field-survey data for signs of binarity, and then used the Robo-AO robotic laser adaptive optics system to verify the parameters of 44 high-confidence targets. We show that BinaryFinder correctly predicts the presence of close companions with a <11% false-positive rate, measures the detected binaries' position angles within 1° to 4° (depending on signal-to-noise ratio and separation), and separations within 25%, and weakly constrains their contrast ratios. When applied to the full PTF data set, we estimate that BinaryFinder will discover and characterize ~450,000 physically associated binary systems with separations <2 arcsec and magnitudes brighter than mR = 18. New wide-field synoptic surveys with high sensitivity and sub-arcsecond angular resolution, such as LSST, will allow BinaryFinder to reliably detect millions of very faint binary systems with separations as small as 0.1 arcsec.

  20. Circumbinary dust disks - reconciling the theory of close binary evolution with observation

    NASA Astrophysics Data System (ADS)

    Brinkworth, Carolyn; Hoard, Donald; Marsh, Tom

    2008-03-01

    The evolution of all close binary systems is driven by the loss of angular momentum from the system. Standard theory invokes two mechanisms for this loss - gravitational radiation and magnetic braking - and forms the backbone of virtually all studies based on binary evolution rates. Recent studies, however, have shown that the extrapolations in which the standard theory is based are wrong, suggesting that the true evolutionary rate of binary systems should be 10 - 10000 slower than previously predicted. To confuse the matter further, observational studies show that binary systems are actually evolving around 1000 times faster than this revised theory suggests, leading to the speculation that there is another angular momentum loss mechanism at work. One of the more likely candidates is the presence of a cool, dusty disk around the binary, which drains angular momentum from the system via tidal coupling. We propose to combine a Spitzer search for circumbinary dust disks with results from an ongoing project to directly measure the evolutionary rates of a number of detached binary systems. By modelling these disks, we will be able to test for any correlation between disk mass and evolutionary rate, and test whether the presence of these dusty disks could finally bring the theory of close binary evolution into line with observation.

  1. Mass Flow in the Close Binary V342 Aquilae

    NASA Astrophysics Data System (ADS)

    Hartman, C. N.; Polidan, R. S.; Welty, A.; Wade, R.; Etzel, P. B.; Bruhweiler, F. C.

    1995-12-01

    Preliminary analysis of the eclipsing binary V342 Aquilae indicates it is undergoing an extremely active phase of mass flow. Three observational datasets provide complete orbital phase coverage of the 3.39 day period across a wide band; IUE spectroscopic data, photometric uvbyRI data, and optical spectroscopy data. IUE observations made in 1991, 1993 and 1995 include 88 low resolution SWP and LWP spectra spanning from 1150 to 3200 Angstroms. The uvbyRI optical photometry data (P. Etzel) were obtained simultaneously with the 1993 IUE observations. Limited KPNO 2.1 meter telescope optical data (A. Welty) covering from 3840 to 9000 Angstroms were taken in 1994. Our UV spectra show very pronounced Fe II absorption lines arising from ground and metastable levels, indicating an extensive circumstellar shell in the system. The strength of this absorption shows both an orbital and a cycle-to-cycle variability. The eclipse spectra display very strong emission from lines such as C II at 1335 Angstroms, Si IV at 1400 Angstroms, and C IV at 1550 Angstroms, with a striking similarity to the eclipse spectra of TT Hydrae. Based upon these data, we have deduced the effective temperatures, spectral types and orbital geometry of the two stars. The UV spectra show the primary is approximately a late B star and the secondary is a late G star. We also present velocity curve results from the optical data along with the resulting mass ratio estimate. Our ongoing analysis aims to understand the unusually large rate of mass flow occuring in V342 Aquilae. P.B.E. acknowledges support under NSF grant AST-9115104.

  2. Using Close White Dwarf + M Dwarf Stellar Pairs to Constrain the Flare Rates in Close Stellar Binaries

    NASA Astrophysics Data System (ADS)

    Morgan, Dylan P.; West, Andrew A.; Becker, Andrew C.

    2016-05-01

    We present a study of the statistical flare rates of M dwarfs (dMs) with close white dwarf (WD) companions (WD+dM; typical separations <1 au). Our previous analysis demonstrated that dMs with close WD companions are more magnetically active than their field counterparts. One likely implication of having a close binary companion is increased stellar rotation through disk-disruption, tidal effects, and/or angular momentum exchange; increased stellar rotation has long been associated with an increase in stellar activity. Previous studies show a strong correlation between dMs that are magnetically active (showing Hα in emission) and the frequency of stellar flare rates. We examine the difference between the flare rates observed in close WD+dM binary systems and field dMs. Our sample consists of a subset of 181 close WD+dM pairs from Morgan et al. observed in the Sloan Digital Sky Survey Stripe 82, where we obtain multi-epoch observations in the Sloan ugriz-bands. We find an increase in the overall flaring fraction in the close WD+dM pairs (0.09 ± 0.03%) compared to the field dMs (0.0108 ± 0.0007%) and a lower flaring fraction for active WD+dMs (0.05 ± 0.03%) compared to active dMs (0.28 ± 0.05%). We discuss how our results constrain both the single and binary dM flare rates. Our results also constrain dM multiplicity, our knowledge of the Galactic transient background, and may be important for the habitability of attending planets around dMs with close companions.

  3. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, S.R.; Christophorou, L.G.

    1988-04-27

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue if the combines physio-electric properties of the mixture components. 9 figs.

  4. VizieR Online Data Catalog: Catalog of massive close binaries (Polushina, 2004)

    NASA Astrophysics Data System (ADS)

    Polushina, T. S.

    2011-11-01

    A catalogue of massive close binaries with early-type components of the main sequence was created. This catalogue includes physical, geometrical and evolution characteristics of these objects, spectral and photometrical pecularities and orbital features. The aim of this work was to research observational phenomena of gas presence around these binaries. The catalogue also contains data on radio and X-ray observations. The catalogue can be used for the creation of observational programmes, for analysis and interpretation of the binary star observational data and for statistical investigations. It contains information extracted from the database of Galactic massive close binaries (M>10M⊙) with early type components. This database is compiled from the General Catalogue of Variable Stars (GCVS) (Kholopov et al., 1985, Cat. B/gcvs), the eighth catalogue of the orbital elements of spectroscopic binary systems (Batten et al., 1989, Cat. V/64), and the Sternberg Astronomical Institute card catalogue of variable stars and current original publications. It excludes O(f), O((f)) and WR stars and systems with relativistic objects. The current sample includes 176 close binaries earlier than about B5. The results of systematization are in two tables. Table 1 contains the sample list of massive close binaries with their basic data. 74 of these systems have been the subject of some spectral observations and some observations of light curves; therefore the absolute parameters of these systems may be determined. Table 2 consists of massive close binaries with early-type components of the main-sequence catalogue, which consists of these 74 systems. They are grouped in the following configurations: detached main-sequence systems, semidetached main-sequence systems, contact systems, four groups which are combinations of these, and finally giant and supergiant systems. All variables in the present data set in Tables 1 and 2 are arranged in the order of their names inside constellations

  5. Photometric observations and analysis of the close binary system DV Aquarii

    SciTech Connect

    Okazaki, A.; Yamasaki, A.; Nurwendaya, C.

    1985-01-01

    Photoelectric BV light curves of the close binary system DV Aqr are presented. These light curves are analyzed with a synthesis method to determine the photometric elements. Physical properties of the system are briefly discussed. It is found that DV Aqr is a detached system consisting of a late-A and a K subgiant star. 12 references.

  6. Tidal evolution of close binary stars. I - Revisiting the theory of the equilibrium tide

    NASA Technical Reports Server (NTRS)

    Zahn, J.-P.

    1989-01-01

    The theory of the equilibrium tide in stars that possess a convective envelope is reexamined critically, taking recent developments into account and treating thermal convection in the most consistent way within the mixing-length approach. The weak points are identified and discussed, in particular, the reduction of the turbulent viscosity when the tidal period becomes shorter than the convective turnover time. An improved version is derived for the secular equations governing the dynamical evolution of close binaries of such type.

  7. Dynamics of magnetic flux tubes in close binary stars. I. Equilibrium and stability properties

    NASA Astrophysics Data System (ADS)

    Holzwarth, V.; Schüssler, M.

    2003-07-01

    Surface reconstructions of active close binary stars based on photometric and spectroscopic observations reveal non-uniform starspot distributions, which indicate the existence of preferred spot longitudes (with respect to the companion star). We consider the equilibrium and linear stability of toroidal magnetic flux tubes in close binaries to examine whether tidal effects are capable to initiate the formation of rising flux loops at preferred longitudes near the bottom of the stellar convection zone. The tidal force and the deviation of the stellar structure from spherical symmetry are treated in lowest-order perturbation theory assuming synchronised close binaries with orbital periods of a few days. The frequency, growth time, and spatial structure of linear eigenmodes are determined by a stability analysis. We find that, despite their small magnitude, tidal effects can lead to a considerable longitudinal asymmetry in the formation probability of flux loops, since the breaking of the axial symmetry due to the presence of the companion star is reinforced by the sensitive dependence of the stability properties on the stellar stratification and by resonance effects. The orientation of preferred longitudes of loop formation depends on the equilibrium configuration and the wave number of the dominating eigenmode. The change of the growth times of unstable modes with respect to the case of a single star is very small.

  8. Three close binaries in different evolutionary stages in the old open cluster NGC 188

    SciTech Connect

    Zhu, L. Y.; Qian, S. B.; Liu, L.; He, J. J.; Liu, N. P.; Zhao, E. G.; Zhang, J.; Wang, J. J.; Soonthornthum, B.

    2014-02-01

    NGC 188 is a good laboratory for studying the formation and evolution of W UMa type contact binaries due to its rich populations of them. We present a detailed photometric study of three short-period close binaries, EP Cep, ES Cep, and V369 Cep, in the old open cluster NGC 188 based on our two-set photometric observations. We discovered that both EP Cep and ES Cep are shallow-contact binaries with continuously decreasing periods. The difference is in their mass ratios. EP Cep has an extremely low-mass ratio, q = 0.15, while ES Cep has a relatively high-mass ratio, q = 0.69, indicating that they lie in different evolutionary stages. ES Cep is likely a newly formed contact binary via a Case A mass transfer, while EP Cep is an evolved system and may be on the oscillations caused by the combined effect of the thermal relaxation oscillation and the variable angular momentum loss. For another system, V369 Cep, we found that it is a primary-filling near-contact binary. Both the semidetached configuration and the continuous decrease in the orbital period indicate that it is undergoing a mass transfer from the primary component to the secondary one. This conclusion is in agreement with the excess luminosity seen in the light curves on the ingress of the secondary minimum produced by the impact of the mass transfer. All of the results suggest that V369 Cep is evolving into contact, and a shallow-contact high-mass ratio system similar to ES Cep will be formed. Then, it will evolve into a low-mass ratio contact binary just like EP Cep, and finally merge into a rapidly rotating single star.

  9. Examining Flare Rates in Close M dwarf + White Dwarf binary pairs

    NASA Astrophysics Data System (ADS)

    Morgan, Dylan P.; West, Andrew A.; Becker, Andrew C.

    2015-01-01

    We present a preliminary study to examine the statistical flare rates for M dwarfs with close white dwarf companions (WD+dM; typical separations < 1 AU). Previous studies have shown a strong correlation between M dwarfs that are active (showing Hα in emission) and their stellar flare rates. Our analysis of M dwarfs with close WD companions demonstrated that the M dwarfs are more active than their field counterparts. One implication of having a close binary companion is presumed to be increased stellar rotation through disk-disruption, tidal effects, and/or angular momentum exchange; increased stellar activity has long been attributed to an increase in stellar rotation. We examine the difference between the flare rates observed in close WD+dM binary systems and field M dwarfs. Our sample consists of a subset of 202 (70 of which are magnetically active) close WD+dM pairs from Morgan et al. that were observed in the Sloan Digital Sky Survey Stripe 82, a transient observing mode where multi-epoch observations in the Sloan ugriz bands were obtained. We present results that will assist in identifying and categorizing transient phenomena and limiting expensive follow-up observations for future time-domain studies, such as LSST.

  10. Examining Flare Rates in Close M Dwarf + White Dwarf Binary Pairs

    NASA Astrophysics Data System (ADS)

    Morgan, Dylan P.; West, Andrew A.

    2014-06-01

    We present a preliminary study to examine the statistical flare rates for M dwarfs with a close white dwarf companion (WD+dM; typical separations < 1 AU). Previous studies show a strong correlation between M dwarfs that are active (showing Hα in emission) and their stellar flare rates. Our previous analysis of M dwarfs with close WD companions demonstrated that the M dwarfs are more active than their field counterparts. One implication of having a close binary companion is presumed to be increased stellar rotation through disk-disruption, tidal effects, and/or angular momentum exchange; increased stellar rotation has long been attributed to an increase in stellar activity for stars. We examine the difference between the flare rates observed in close WD+dM binary systems and field M dwarfs. Our sample consists of a subset of 202 (70 of which are magnetically active) close WD+dM pairs from Morgan et al. that were observed in the Sloan Digital Sky Survey Stripe 82, a transient observing mode where multi-epoch observations in the Sloan ugriz bands were obtained.

  11. Proof of polar ejection from the close-binary core of the planetary nebula Abell 63

    NASA Astrophysics Data System (ADS)

    Mitchell, Deborah L.; Pollacco, Don; O'Brien, T. J.; Bryce, M.; López, J. A.; Meaburn, J.; Vaytet, N. M. H.

    2007-02-01

    We present the first detailed kinematical analysis of the planetary nebula Abell 63, which is known to contain the eclipsing close-binary nucleus UU Sge. Abell 63 provides an important test case in investigating the role of close-binary central stars on the evolution of planetary nebulae. Longslit observations were obtained using the Manchester echelle spectrometer combined with the 2.1-m San Pedro Martir Telescope. The spectra reveal that the central bright rim of Abell 63 has a tube-like structure. A deep image shows collimated lobes extending from the nebula, which are shown to be high-velocity outflows. The kinematic ages of the nebular rim and the extended lobes are calculated to be 8400 +/- 500 and 12900 +/- 2800 yr, respectively, which suggests that the lobes were formed at an earlier stage than the nebular rim. This is consistent with expectations that disc-generated jets form immediately after the common envelope phase. A morphological-kinematical model of the central nebula is presented and the best-fitting model is found to have the same inclination as the orbital plane of the central binary system; this is the first proof that a close-binary system directly affects the shaping of its nebula. A Hubble-type flow is well-established in the morphological-kinematical modelling of the observed line profiles and imagery. Two possible formation models for the elongated lobes of Abell 63 are considered, (i) a low-density, pressure-driven jet excavates a cavity in the remnant asymptotic giant branch (AGB) envelope; (ii) high-density bullets form the lobes in a single ballistic ejection event.

  12. The Formation Process of Massive Close Spectroscopic Binaries: The Fission Hypothesis Revisited

    NASA Astrophysics Data System (ADS)

    Zinnecker, H.; Ostriker, J.

    2013-06-01

    The vast majority of massive Main-Sequence stars (M>20 Mo) seem to be born in close interactive binary systems (Chini et al. 2012, Sana et al. 2012). The very process by which these systems form is still a mystery and has received little attention so far. Because the binary separation is so tight (less than 1AU), break-up of a critically rotating protostar ("fission") remains an interesting possibility. However, standard current star formation theory treats fission as unlikely (cf. Tohline 2002, ARAA). We question this view and investigate minimum energy states of compressible polytropic analogs to the well-known incompressible MacLaurin spheroids. Dynamical non-axisymmetric instability at a critical ratio of rotational to gravitational energy (cf. Ostriker and Bodenheimer 1973) during the shrinkage of an accreting, rapidly rotating, bloated, massive protostar AFTER ACCRETION DECLINES may provide the conditions for break-up into a close binary system. Time dependent hydro-dynamical simulations are required to either confirm or reject this hypothesis.

  13. Bit-table based biclustering and frequent closed itemset mining in high-dimensional binary data.

    PubMed

    Király, András; Gyenesei, Attila; Abonyi, János

    2014-01-01

    During the last decade various algorithms have been developed and proposed for discovering overlapping clusters in high-dimensional data. The two most prominent application fields in this research, proposed independently, are frequent itemset mining (developed for market basket data) and biclustering (applied to gene expression data analysis). The common limitation of both methodologies is the limited applicability for very large binary data sets. In this paper we propose a novel and efficient method to find both frequent closed itemsets and biclusters in high-dimensional binary data. The method is based on simple but very powerful matrix and vector multiplication approaches that ensure that all patterns can be discovered in a fast manner. The proposed algorithm has been implemented in the commonly used MATLAB environment and freely available for researchers.

  14. Hydrodynamics of rotating stars and close binary interactions: Compressible ellipsoid models

    NASA Technical Reports Server (NTRS)

    Lai, Dong; Rasio, Frederic A.; Shapiro, Stuart L.

    1994-01-01

    We develop a new formalism to study the dynamics of fluid polytropes in three dimensions. The stars are modeled as compressible ellipsoids, and the hydrodynamic equations are reduced to a set of ordinary differential equations for the evolution of the principal axes and other global quantities. Both viscous dissipation and the gravitational radiation reaction are incorporated. We establish the validity of our approximations and demonstrate the simplicity and power of the method by rederiving a number of known results concerning the stability and dynamical oscillations of rapidly rotating polytropes. In particular, we present a generalization to compressible fluids of Chandrasekhar's classical results for the secular and dynamical instabilities of incompressible Maclaurin spheroids. We also present several applications of our method to astrophysical problems of great current interest, such as the tidal disruption of a star by a massive black hole, the coalescence of compact binaries driven by the emission of gravitational waves, and the development of instabilities in close binary systems.

  15. Massive star evolution in close binaries. Conditions for homogeneous chemical evolution

    NASA Astrophysics Data System (ADS)

    Song, H. F.; Meynet, G.; Maeder, A.; Ekström, S.; Eggenberger, P.

    2016-01-01

    Aims: We investigate the impact of tidal interactions, before any mass transfer, on various properties of the stellar models. We study the conditions for obtaining homogeneous evolution triggered by tidal interactions, and for avoiding any Roche lobe overflow (RLOF) during the main-sequence phase. By homogeneous evolution, we mean stars evolving with a nearly uniform chemical composition from the centre to the surface. Methods: We consider the case of rotating stars computed with a strong core-envelope coupling mediated by an interior magnetic field. Models with initial masses between 15 and 60 M⊙, for metallicities between 0.002 and 0.014 and with initial rotation equal to 30% and 66% the critical rotation on the zero age main sequence, are computed for single stars and for stars in close binary systems. We consider close binary systems with initial orbital periods equal to 1.4, 1.6, and 1.8 days and a mass ratio equal to 3/2. Results: In models without any tidal interaction (single stars and wide binaries), homogeneous evolution in solid body rotating models is obtained when two conditions are realised: the initial rotation must be high enough, and the loss of angular momentum by stellar winds should be modest. This last point favours metal-poor fast rotating stars. In models with tidal interactions, homogeneous evolution is obtained when rotation imposed by synchronisation is high enough (typically a time-averaged surface velocities during the main-sequence phase above 250 km s-1), whatever the mass losses. We present plots that indicate for which masses of the primary and for which initial periods the conditions for the homogenous evolution and avoidance of the RLOF are met, for various initial metallicities and rotations. In close binaries, mixing is stronger at higher than at lower metallicities. Homogeneous evolution is thus favoured at higher metallicities. RLOF avoidance is favoured at lower metallicities because stars with less metals remain more

  16. The binary fraction of planetary nebula central stars - I. A high-precision, I-band excess search

    NASA Astrophysics Data System (ADS)

    De Marco, Orsola; Passy, Jean-Claude; Frew, D. J.; Moe, Maxwell; Jacoby, G. H.

    2013-01-01

    a binary fraction of 100-107 per cent. The two numbers should be the same and the discrepancy is likely due to small-number statistics. Finally, we note how the previously derived short-period PN binary fraction of 15-20 per cent is far larger than expected based on the main-sequence binary fraction and period distribution. As a byproduct of our analysis we present an accurately vetted compilation of observed main-sequence star magnitudes, colours and masses, which can serve as a reference for future studies. We also present synthetic colours of hot stars as a function of temperature (20-170 kK) and gravity (log g = 6-8) for Solar and PG1159 compositions.

  17. WZ Cephei: A Close Binary at the Beginning of Contact Phase

    NASA Astrophysics Data System (ADS)

    Zhu, L. Y.; Qian, S. B.

    2009-12-01

    Photometric photoelectric data of the short-period close binary system, WZ Cephei, are presented. A new photometric analysis with the 2003 version of the Wilson-Devinney method confirmed that it is a shallow contact binary (f ~ 13.3%) with a high level of spot activity on the primary component. Combining new determined times of light minimum with the others published in the literature, the period change of the binary star is investigated. A periodic variation, with a period of 34.2 years and an amplitude of 0fd013, was discovered to be superimposed on a long-term period decrease (dP/dt = -8.8 × 10-8 days year-1). Both the secular period decrease and the shallow contact configuration suggest that this binary system is at the beginning of contact phase. It is on the way to evolving into a normal overcontact phase via secular angular momentum loss and/or mass transfer from the more massive component to the less massive one. The period oscillation can be explained either by the light-time effect due to the presence of a third body or by magnetic activity. On the one hand, if it is caused by the light-time effect, the mass and the orbital radius of the additional body should be m 3 = 0.17 M sun and a 3 = 26.6 AU, respectively, when this body is coplanar to the orbit of the eclipsing pair. On the other hand, since the system shows high levels of spot activity, the period oscillation may be explained as a consequence of magnetic cycles. In this case, the required variation of the quadrupole moment is calculated to be 9.2 × 1049 g cm2.

  18. The close binary frequency of Wolf-Rayet stars as a function of metallicity in M31 and M33

    SciTech Connect

    Neugent, Kathryn F.; Massey, Philip E-mail: phil.massey@lowell.edu

    2014-07-01

    Massive star evolutionary models generally predict the correct ratio of WC-type and WN-type Wolf-Rayet stars at low metallicities, but underestimate the ratio at higher (solar and above) metallicities. One possible explanation for this failure is perhaps single-star models are not sufficient and Roche-lobe overflow in close binaries is necessary to produce the 'extra' WC stars at higher metallicities. However, this would require the frequency of close massive binaries to be metallicity dependent. Here we test this hypothesis by searching for close Wolf-Rayet binaries in the high metallicity environments of M31 and the center of M33 as well as in the lower metallicity environments of the middle and outer regions of M33. After identifying ∼100 Wolf-Rayet binaries based on radial velocity variations, we conclude that the close binary frequency of Wolf-Rayets is not metallicity dependent and thus other factors must be responsible for the overabundance of WC stars at high metallicities. However, our initial identifications and observations of these close binaries have already been put to good use as we are currently observing additional epochs for eventual orbit and mass determinations.

  19. A classical model for closed-loop diagrams of binary liquid mixtures

    SciTech Connect

    Schnitzler, J.v.; Prausnitz, J.M. |

    1994-03-01

    A classical lattice model for closed-loop temperature-composition phase diagrams has been developed. It considers the effect of specific interactions, such as hydrogen bonding, between dissimilar components. This van Laar-type model includes a Flory-Huggins term for the excess entropy of mixing. It is applied to several liquid-liquid equilibria of nonelectrolytes, where the molecules of the two components differ in size. The model is able to represent the observed data semi-quantitatively, but in most cases it is not flexible enough to predict all parts of the closed loop quantitatively. The ability of the model to represent different binary systems is discussed. Finally, attention is given to a correction term, concerning the effect of concentration fluctuations near the upper critical solution temperature.

  20. THE DOUBLE-DEGENERATE NUCLEUS OF THE PLANETARY NEBULA TS 01: A CLOSE BINARY EVOLUTION SHOWCASE

    SciTech Connect

    Tovmassian, Gagik; Richer, Michael G.; Yungelson, Lev; Rauch, Thomas; Suleimanov, Valery; Napiwotzki, Ralf; Stasinska, Grazyna; Tomsick, John; Wilms, Joern; Morisset, Christophe; Pena, Miriam

    2010-05-01

    We present a detailed investigation of SBS 1150+599A, a close binary star hosted by the planetary nebula PN G135.9+55.9 (TS 01). The nebula, located in the Galactic halo, is the most oxygen-poor known to date and is the only one known to harbor a double degenerate core. We present XMM-Newton observations of this object, which allowed the detection of the previously invisible component of the binary core, whose existence was inferred so far only from radial velocity (RV) and photometric variations. The parameters of the binary system were deduced from a wealth of information via three independent routes using the spectral energy distribution (from the infrared to X-rays), the light and RV curves, and a detailed model atmosphere fitting of the stellar absorption features of the optical/UV component. We find that the cool component must have a mass of 0.54 {+-} 0.2 M{sub sun}, an average effective temperature, T{sub eff}, of 58,000 {+-} 3000 K, a mean radius of 0.43 {+-} 0.3 R{sub sun}, a gravity, log g = 5.0 {+-} 0.3, and that it nearly fills its Roche lobe. Its surface elemental abundances are found to be: 12 + log He/H = 10.95 {+-} 0.04 dex, 12 + log C/H = 7.20 {+-} 0.3 dex, 12 + log N/H < 6.92, and 12 + log O/H < 6.80, in overall agreement with the chemical composition of the planetary nebula. The hot component has T{sub eff} = 160-180 kK, a luminosity of about {approx}10{sup 4} L{sub sun} and a radius slightly larger than that of a white dwarf. It is probably bloated and heated as a result of intense accretion and nuclear burning on its surface in the past. The total mass of the binary system is very close to the Chandrasekhar limit. This makes TS 01 one of the best Type Ia supernova progenitor candidates. We propose two possible scenarios for the evolution of the system up to its present stage.

  1. Characterization of close visual binaries from the AstraLux Large M Dwarf Survey

    NASA Astrophysics Data System (ADS)

    Bergfors, C.; Brandner, W.; Bonnefoy, M.; Schlieder, J.; Janson, M.; Henning, Th.; Chauvin, G.

    2016-03-01

    We present Very Large Telescope/Spectrograph for INtegral Field Observations in the Near Infrared (VLT/SINFONI) J, H + K spectra of seven close visual pairs in M dwarf binary/triple systems, discovered or observed by the AstraLux M dwarf survey. We determine the spectral types to within ±1.0 subclasses from comparison to template spectra and the strength of K-band water absorption, and derive effective temperatures. The results are compared to optical spectral types of the unresolved binary/multiple systems, and we confirm that our photometric method to derive spectral types in the AstraLux M dwarf survey is accurate. We look for signs of youth such as chromospheric activity and low surface gravity, and find an age in the range 0.25-1 Gyr for the GJ 852 system. Strong Li absorption is detected in optical spectra of the triple system J024902 obtained with the Fiberfed Extended Range Optical Spectrograph (FEROS) at the European Southern Observatory (ESO)-Max-Planck-Gesellschaft (MPG) 2.2 m telescope. The equivalent width of the absorption suggests an age consistent with the β Pic moving group. However, further observations are needed to establish group membership. Ongoing orbital monitoring will provide dynamical masses and thus calibration of evolutionary models for low mass stars.

  2. Period analysis of three close binary systems: TW And, TT Her and W UMi

    NASA Astrophysics Data System (ADS)

    Kreiner, J. M.; Pribulla, T.; Tremko, J.; Stachowski, G. S.; Zakrzewski, B.

    2008-02-01

    Orbital period changes of three close binaries, TW And, TT Her and W UMi, were studied using the Kraków data base of minima of eclipsing binaries, and new photoelectric observations obtained by the authors. The interval of the observations spans roughly a century. The major orbital period change in TW And is explained by the presence of a third body with P3 = 49.6 yr and a continuous secular period increase. A third body, with P3 = 41.0 yr, was also found in the system TT Her. The (O-C) diagram of W UMi can be interpreted as either an abrupt orbital period decrease which occurred around the end of 1973 or as a secular orbital period decrease combined with cyclic change. In this case, the orbital period of the third body is 62.2 yr and the sum of squares of residuals is lower than for a broken-line fit, therefore cyclic variations should be preferred. In all three systems, the third body is a low-mass companion.

  3. The chemical evolution of the secondary stars in close binary systems during nova outbursts

    NASA Astrophysics Data System (ADS)

    Marks, P. B.; Sarna, M. J.; Prialnik, D.

    1997-09-01

    We present stellar evolutionary calculations of secondary stars in close binary systems. We include the effect of re-accretion of material ejected during the nova outbursts of the semi-detached phase of evolution. Our models give us the detailed composition of the secondary star throughout its whole evolution, since we use an extended nuclear reaction network. Using the data concerning the isotopic and element abundances of the surface of the secondary star, we show how the ratios of ^12C/^13C, ^14N/^15N and ^16O/^17O and the abundances of C and N are affected by re-accretion of ejecta material. We suggest observational tests which, when compared with our results, will allow us to make predictions concerning the evolutionary state of the systems observed.

  4. Accuracy and effectualness of closed-form, frequency-domain waveforms for nonspinning black hole binaries

    NASA Astrophysics Data System (ADS)

    Damour, Thibault; Nagar, Alessandro; Trias, Miquel

    2011-01-01

    The coalescences of binary black hole systems, here taken to be nonspinning, are among the most promising sources for gravitational wave (GW) ground-based detectors, such as LIGO and Virgo. To detect the GW signals emitted by binary black holes and measure the parameters of the source, one needs to have in hand a bank of GW templates that are both effectual (for detection) and accurate (for measurement). We study the effectualness and the accuracy of the two types of parametrized banks of templates that are directly defined in the frequency domain by means of closed-form expressions, namely, “post-Newtonian” (PN) and “phenomenological” models. In the absence of knowledge of the (continuous family of) exact waveforms, our study assumes as fiducial, target waveforms the ones generated by the most accurate version of the effective-one-body formalism, calibrated upon a few high-accuracy numerical-relativity (NR) waveforms. We find that, for initial GW detectors the use, at each point of parameter space, of the best closed-form template (among PN and phenomenological models) leads to an effectualness >97% over the entire mass range and >99% in an important fraction of parameter space; however, when considering advanced detectors, both of the closed-form frequency-domain models fail to be effectual enough in significant domains of the two-dimensional [total mass and mass ratio] parameter space. Moreover, we find that, for both initial and advanced detectors, the two closed-form frequency-domain models fail to satisfy the minimal required accuracy standard in a very large domain of the two-dimensional parameter space. In addition, a side result of our study is the determination, as a function of the mass ratio, of the maximum frequency at which a frequency-domain PN waveform can be “joined” onto a NR-calibrated effective-one-body waveform without undue loss of accuracy. In the case of mass ratios larger than 4∶1 this maximum frequency occurs well before the

  5. Spectroscopy of close visual binary components of the stable shell star 1 Delphini

    NASA Astrophysics Data System (ADS)

    Kubát, Jiří; Kubátová, Brankica; Doležalová, Barbora; Iliev, Lubomir; Šlechta, Miroslav

    2016-03-01

    Stable shell stars are ideal objects for studying basic physical principles of the formation of disks in Be stars. If these stars have a close unresolved visual companion, its contribution toward the modelling of the disk cannot be overlooked, as is sometimes done. The study aims to spectroscopically resolve close visual binary Be (shell) star 1 Del, which up to now was only resolved by speckle or micrometric measurements. The integral field spectroscopy obtained by the SINFONI spectrograph at the VLT telescope in the European Southern Observatory (ESO) in the infrared region was used; we supplemented these observations with visual spectroscopy with the Perek Telescope at the Ondřejov Observatory. Spectra of 1 Del were successfully resolved, and, for the first time, spectra of 1 Del B were obtained. We found that 1 Del A is a Be/shell star, while 1 Del B is not an emission-line object. Based on observations collected with the Perek 2-m Telescope at the Ondřejov Observatory, Czech Republic and the SINFONI spectrograph at UT4-Yepun in ESO during the observing programme 093.D-0172.The reduced spectra as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A22

  6. The close binary properties of massive stars in the Milky Way and low-metallicity Magellanic Clouds

    SciTech Connect

    Moe, Maxwell; Di Stefano, Rosanne

    2013-12-01

    In order to understand the rates and properties of Type Ia and Type Ib/c supernovae, X-ray binaries, gravitational wave sources, and gamma-ray bursts as a function of galactic environment and cosmic age, it is imperative that we measure how the close binary properties of O- and B-type stars vary with metallicity. We have studied eclipsing binaries with early B main-sequence primaries in three galaxies with different metallicities: the Large and Small Magellanic Clouds (LMC and SMC, respectively) and the Milky Way (MW). The observed fractions of early B stars that exhibit deep eclipses 0.25 < Δm (mag) < 0.65 and orbital periods 2 < P (days) < 20 in the MW, LMC, and SMC span a narrow range of (0.7-1.0)%, which is a model-independent result. After correcting for geometrical selection effects and incompleteness toward low-mass companions, we find for early B stars in all three environments (1) a close binary fraction of (22 ± 5)% across orbital periods 2 < P (days) < 20 and mass ratios q = M {sub 2}/M {sub 1} > 0.1, (2) an intrinsic orbital period distribution slightly skewed toward shorter periods relative to a distribution that is uniform in log P, (3) a mass-ratio distribution weighted toward low-mass companions, and (4) a small, nearly negligible excess fraction of twins with q > 0.9. Our fitted parameters derived for the MW eclipsing binaries match the properties inferred from nearby, early-type spectroscopic binaries, which further validates our results. There are no statistically significant trends with metallicity, demonstrating that the close binary properties of massive stars do not vary across metallicities –0.7 < log(Z/Z {sub ☉}) < 0.0 beyond the measured uncertainties.

  7. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1988-06-28

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  8. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, Loucas G.; Hunter, Scott R.

    1990-01-01

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

  9. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1990-06-26

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  10. A Model for Short Gamma-Ray Bursts: Heated Neutron Stars in Close Binary Systems

    SciTech Connect

    Salmonson, J.D.; Wilson, J.R.

    2001-12-17

    In this paper we present a model for the short (< second) population of gamma-ray bursts (GRBs). In this model heated neutron stars in a close binary system near their last stable orbit emit neutrinos at large luminosities ({approx} 10{sup 53} ergs/sec). A fraction of these neutrinos will annihilate to form an e{sup +}e{sup -} pair plasma wind which will, in turn, expand and recombine to photons which make the gamma-ray burst. We study neutrino annihilation and show that a substantial fraction ({approx}1/2) of energy deposited comes from inter-star neutrinos, where each member of the neutrino pair originates from each neutron star. Thus, in addition to the annihilation of neutrinos blowing off of a single star, we have a new source of baryon free energy that is deposited between the stars. To model the e{sup +}e{sup -} pair plasma wind between stars, we do three-dimensional relativistic numerical hydrodynamic calculations. Preliminary results are also presented of new, fully general relativistic calculations of gravitationally attracting stars falling from infinity with no angular momentum. These simulations exhibit a compression effect.

  11. KEPLER-14b: A MASSIVE HOT JUPITER TRANSITING AN F STAR IN A CLOSE VISUAL BINARY

    SciTech Connect

    Buchhave, Lars A.; Latham, David W.; Carter, Joshua A.; Desert, Jean-Michel; Torres, Guillermo; Adams, Elisabeth R.; Charbonneau, David B.; Dupree, Andrea K.; Fressin, Francois; Bryson, Stephen T.; Howell, Steve B.; Ciardi, David R.; Fischer, Debra A.; Gautier, Thomas N.; Isaacson, Howard; Marcy, Geoffrey W.; Jenkins, Jon M.

    2011-11-01

    We present the discovery of a hot Jupiter transiting an F star in a close visual (0.''3 sky projected angular separation) binary system. The dilution of the host star's light by the nearly equal magnitude stellar companion ({approx}0.5 mag fainter) significantly affects the derived planetary parameters, and if left uncorrected, leads to an underestimate of the radius and mass of the planet by 10% and 60%, respectively. Other published exoplanets, which have not been observed with high-resolution imaging, could similarly have unresolved stellar companions and thus have incorrectly derived planetary parameters. Kepler-14b (KOI-98) has a period of P = 6.790 days and, correcting for the dilution, has a mass of M{sub p} = 8.40{sup +0.35}{sub -0.34} M{sub J} and a radius of R{sub p} = 1.136{sup +0.073}{sub -0.054} R{sub J}, yielding a mean density of {rho}{sub p} = 7.1 {+-} 1.1 g cm{sup -3}.

  12. The variable stars program of Júlia observatory & computer tomography insight into the surrounding structures of the close binaries

    NASA Astrophysics Data System (ADS)

    Bahýl, V.; Gajtanska, M.

    2016-03-01

    Before all we introduce our observatory named "Júlia", with its technical equipment and with its scientific observational program. The core of our paper there is the presentation of the achieved results in the DSLR observations of the selected eclipsing binaries. The results obtained in this field after the change to the observations with the CCD Camera MI G2-1600 will be also presented. Finally we present and prove our possibilities in the modeling of the surrounding of the close binaries by the computer tomography method.

  13. A systematic search for close supermassive black hole binaries in the Catalina Real-time Transient Survey

    NASA Astrophysics Data System (ADS)

    Graham, Matthew J.; Djorgovski, S. G.; Stern, Daniel; Drake, Andrew J.; Mahabal, Ashish A.; Donalek, Ciro; Glikman, Eilat; Larson, Steve; Christensen, Eric

    2015-10-01

    Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variability (or nanohertz frequency gravitational waves). Following our detection of a 5.2-year periodic signal in the quasar PG 1302-102, we present a novel analysis of the optical variability of 243 500 known spectroscopically confirmed quasars using data from the Catalina Real-time Transient Survey (CRTS) to look for close (<0.1 pc) SMBH systems. Looking for a strong Keplerian periodic signal with at least 1.5 cycles over a baseline of nine years, we find a sample of 111 candidate objects. This is in conservative agreement with theoretical predictions from models of binary SMBH populations. Simulated data sets, assuming stochastic variability, also produce no equivalent candidates implying a low likelihood of spurious detections. The periodicity seen is likely attributable to either jet precession, warped accretion discs or periodic accretion associated with a close SMBH binary system. We also consider how other SMBH binary candidates in the literature appear in CRTS data and show that none of these are equivalent to the identified objects. Finally, the distribution of objects found is consistent with that expected from a gravitational-wave-driven population. This implies that circumbinary gas is present at small orbital radii and is being perturbed by the black holes. None of the sources is expected to merge within at least the next century. This study opens a new unique window to study a population of close SMBH binaries that must exist according to our current understanding of galaxy and SMBH evolution.

  14. The comparison of binary- and ternary-fission configurations close to the instant of scission

    NASA Astrophysics Data System (ADS)

    Guseva, I. S.; Gagarski, A. M.; Gusev, Yu. I.; Petrov, G. A.; Valski, G. V.

    2013-07-01

    A new way to bring into comparison the binary- and ternary-fission configurations is proposed. The method is founded on recently discovered ROT effect. The angle of fission axis deflection from its initial orientation at the moment of scission comes into existence as a result of dividing system rotation and carries information about fissioning nucleus deformation. The comparison of proper angles for binary and ternary fission can be used to estimate the difference in the rupture configurations.

  15. THE QUASI-ROCHE LOBE OVERFLOW STATE IN THE EVOLUTION OF CLOSE BINARY SYSTEMS CONTAINING A RADIO PULSAR

    SciTech Connect

    Benvenuto, O. G.; De Vito, M. A.

    2015-01-01

    We study the evolution of close binary systems formed by a normal (solar composition), intermediate-mass-donor star together with a neutron star. We consider models including irradiation feedback and evaporation. These nonstandard ingredients deeply modify the mass-transfer stages of these binaries. While models that neglect irradiation feedback undergo continuous, long-standing mass-transfer episodes, models including these effects suffer a number of cycles of mass transfer and detachment. During mass transfer, the systems should reveal themselves as low-mass X-ray binaries (LMXBs), whereas when they are detached they behave as binary radio pulsars. We show that at these stages irradiated models are in a Roche lobe overflow (RLOF) state or in a quasi-RLOF state. Quasi-RLOF stars have radii slightly smaller than their Roche lobes. Remarkably, these conditions are attained for an orbital period as well as donor mass values in the range corresponding to a family of binary radio pulsars known as ''redbacks''. Thus, redback companions should be quasi-RLOF stars. We show that the characteristics of the redback system PSR J1723-2837 are accounted for by these models. In each mass-transfer cycle these systems should switch from LMXB to binary radio pulsar states with a timescale of approximately one million years. However, there is recent and fast growing evidence of systems switching on far shorter, human timescales. This should be related to instabilities in the accretion disk surrounding the neutron star and/or radio ejection, still to be included in the model having the quasi-RLOF state as a general condition.

  16. The Quasi-Roche Lobe Overflow State in the Evolution of Close Binary Systems Containing a Radio Pulsar

    NASA Astrophysics Data System (ADS)

    Benvenuto, O. G.; De Vito, M. A.; Horvath, J. E.

    2015-01-01

    We study the evolution of close binary systems formed by a normal (solar composition), intermediate-mass-donor star together with a neutron star. We consider models including irradiation feedback and evaporation. These nonstandard ingredients deeply modify the mass-transfer stages of these binaries. While models that neglect irradiation feedback undergo continuous, long-standing mass-transfer episodes, models including these effects suffer a number of cycles of mass transfer and detachment. During mass transfer, the systems should reveal themselves as low-mass X-ray binaries (LMXBs), whereas when they are detached they behave as binary radio pulsars. We show that at these stages irradiated models are in a Roche lobe overflow (RLOF) state or in a quasi-RLOF state. Quasi-RLOF stars have radii slightly smaller than their Roche lobes. Remarkably, these conditions are attained for an orbital period as well as donor mass values in the range corresponding to a family of binary radio pulsars known as "redbacks." Thus, redback companions should be quasi-RLOF stars. We show that the characteristics of the redback system PSR J1723-2837 are accounted for by these models. In each mass-transfer cycle these systems should switch from LMXB to binary radio pulsar states with a timescale of approximately one million years. However, there is recent and fast growing evidence of systems switching on far shorter, human timescales. This should be related to instabilities in the accretion disk surrounding the neutron star and/or radio ejection, still to be included in the model having the quasi-RLOF state as a general condition.

  17. V753 MON: A UNIQUE CLOSE BINARY JUST AFTER THE EVOLUTIONARY STAGE WITH THE SHORTEST PERIOD DURING MASS TRANSFER

    SciTech Connect

    Qian, S.-B.; Zhang, J.; Wang, J.-J.; Zhu, L.-Y.; Liu, L.; Zhao, E. G.; Li, L.-J.; He, J.-J.

    2013-08-15

    We discovered that the O-C curve of V753 Mon shows an upward parabolic change while undergoing a cyclic variation with a period of 13.5 yr. The upward parabolic change reveals a long-term period increase at a rate of P-dot = +7.8 x 10{sup -8} days yr{sup -1}. Photometric solutions determined using the Wilson-Devinney method confirm that V753 Mon is a semi-detached binary system where the slightly less massive, hotter component star is transferring mass to the more massive one. This is in agreement with the long-term increase of the orbital period. The increase of the orbital period, the mass ratio very close to unity, and the semi-detached configuration with a less massive lobe-filling component all suggest that V753 Mon is on a key evolutionary stage just after the evolutionary stage with the shortest period during mass transfer. The results in this paper will shed light on the formation of massive contact binaries and the evolution of binary stars. The cyclic oscillation in the O-C diagram indicates that V753 Mon may be a triple system containing an extremely cool stellar companion that may play an important role for the formation and evolution in the binary system.

  18. Close encounters of the third-body kind. [intruding bodies in binary star systems

    NASA Technical Reports Server (NTRS)

    Davies, M. B.; Benz, W.; Hills, J. G.

    1994-01-01

    We simulated encounters involving binaries of two eccentricities: e = 0 (i.e., circular binaries) and e = 0.5. In both cases the binary contained a point mass of 1.4 solar masses (i.e., a neutron star) and a 0.8 solar masses main-sequence star modeled as a polytrope. The semimajor axes of both binaries were set to 60 solar radii (0.28 AU). We considered intruders of three masses: 1.4 solar masses (a neutron star), 0.8 solar masses (a main-sequence star or a higher mass white dwarf), and 0.64 solar masses (a more typical mass white dwarf). Our strategy was to perform a large number (40,000) of encounters using a three-body code, then to rerun a small number of cases with a three-dimensional smoothed particle hydrodynamics (SPH) code to determine the importance of hydrodynamical effects. Using the results of the three-body runs, we computed the exchange across sections, sigma(sub ex). From the results of the SPH runs, we computed the cross sections for clean exchange, denoted by sigma(sub cx); the formation of a triple system, denoted by sigma(sub trp); and the formation of a merged binary with an object formed from the merger of two of the stars left in orbit around the third star, denoted by sigma(sub mb). For encounters between either binary and a 1.4 solar masses neutron star, sigma(sub cx) approx. 0.7 sigma(sub ex) and sigma(sub mb) + sigma(sub trp) approx. 0.3 sigma(sub ex). For encounters between either binary and the 0.8 solar masses main-sequence star, sigma(sub cx) approx. 0.50 sigma(sub ex) and sigma(sub mb) + sigma(sub trp) approx. 1.0 sigma(sub ex). If the main sequence star is replaced by a main-sequence star of the same mass, we have sigma(sub cx) approx. 0.5 sigma(sub ex) and sigma(sub mb) + sigma(sub trp) approx. 1.6 sigma(sub ex). Although the exchange cross section is a sensitive function of intruder mass, we see that the cross section to produce merged binaries is roughly independent of intruder mass. The merged binaries produced have semi

  19. Structure and spectra of irradiated secondaries in close binaries. A model calculation of the pre-cataclysmic variable UU Sagittae

    NASA Astrophysics Data System (ADS)

    Wawrzyn, A. C.; Barman, T. S.; Günther, H. M.; Hauschildt, P. H.; Exter, K. M.

    2009-10-01

    Context: The standard stellar model atmosphere ignores the influence of external radiation. This assumption, while sufficient for most stars, fails for many short-period binaries. Aims: In setting up combined model atmospheres for close binaries, we want to constrain the parameters of both components, especially in the case of a hot primary component strongly influencing its cool secondary companion. This situation can be found after common envelope evolution (CEE). The status of both components today allows one to retrace the CEE itself. Methods: We used our stellar atmosphere code PHOENIX, which includes the effect of irradiation in its radiation transport equation, to investigate the close binary star UU Sge. We combined our calculated spectra of both components, weighted by their visible size, and adjusted the input parameters until reasonable agreement with observations is reached. Results: We derive a range of 80 000-85 000 K for the effective temperature of the primary (Teff, p) and give a rough estimate for the primary's abundances, particularly the nitrogen enrichment. The heated day-side of the secondary has an apparent “effective” or equilibrium temperature of 24 000-26 000 K, nearly independent of its intrinsic luminosity. It shows an enhancement in nitrogen and carbon. Conclusions: The evolution of the primary and secondary stars were strongly influenced by the other's presence. Radiation from the primary on the secondary's day-side is still an important factor in understanding the secondary's atmospheric structure.

  20. The first photometric investigation of the neglected close binary star AQ Com

    NASA Astrophysics Data System (ADS)

    Liu, N.-P.; Qian, S.-B.; Wang, J.-J.; Zhao, E.-G.; Snoonthornthum, B.; Zhu, L.-Y.; Zhou, X.

    2014-10-01

    AQ Com is a W UMa-type binary star with a period of 0.28133 days that was discovered about fifty years ago. However, it was neglected for photometric investigation. Complete light curves in Rc and Ic bands are presented that show a positive O'Conell effect. The light maxima following the primary minima are higher than the other ones in both bands. Photometric solutions obtained with the W-D (Wilson and Devinney) method suggest that AQ Com is a contact binary with a contact degree of f = 21.4 (± 6.2) % . It is found that the contact binary is a W-type system with a mass ratio of q = 2.86 where the less massive component is hotter than the more massive one in a common convective envelope. The asymmetries of the light curves are explained by two dark spots on the more massive component. By combining several determined times of light minimum with the others compiled from the literature, it is detected that the Observed-Calculated (O-C) curve may display a cyclic change with a period of 8.5 years and an amplitude of 0.0016 days. The cyclic oscillation may be caused by the presence of a cool third stellar object at an orbital separation of about ∼ 4.2 AU. However, more data are needed to confirm the existence of the third body.

  1. A LARGE SYSTEMATIC SEARCH FOR CLOSE SUPERMASSIVE BINARY AND RAPIDLY RECOILING BLACK HOLES

    SciTech Connect

    Eracleous, Michael; Boroson, Todd A.; Halpern, Jules P.; Liu Jia

    2012-08-01

    We have carried out a systematic search for subparsec supermassive black hole (BH) binaries among z {approx}< 0.7 Sloan Digital Sky Survey quasars. These are predicted by models of supermassive BH and host galaxy coevolution, therefore their census and population properties constitute an important test of these models. In our working hypothesis, one of the two BHs accretes at a much higher rate than the other and carries with it the only broad emission line region of the system, making the system analogous to a single-lined spectroscopic binary star. Accordingly, we used spectroscopic principal component analysis to search for broad H{beta} emission lines that are displaced from the quasar rest frame by |{Delta} v| {approx}> 1000 km s{sup -1}. This method also yields candidates for rapidly recoiling BHs. Of the 88 candidates, several were previously reported in the literature. We found a correlation between the peak offset and skewness of the broad H{beta} profiles, suggesting a common physical explanation for these profiles. We carried out follow-up spectroscopic observations of 68 objects to search for changes in the peak velocities of the H{beta} lines. We measured statistically significant changes in 14 objects, with implied accelerations between -120 and +120 km s{sup -1} yr{sup -1}. Interpreting the offset broad emission lines as signatures of supermassive binaries is subject to many caveats. Many more follow-up observations over a long temporal baseline are needed to characterize the variability pattern of the broad lines and test that it is consistent with orbital motion. The possibility that some of the objects in this sample are rapidly recoiling BHs remains open.

  2. A Large Systematic Search for Close Supermassive Binary and Rapidly Recoiling Black Holes

    NASA Astrophysics Data System (ADS)

    Eracleous, Michael; Boroson, Todd A.; Halpern, Jules P.; Liu, Jia

    2012-08-01

    We have carried out a systematic search for subparsec supermassive black hole (BH) binaries among z <~ 0.7 Sloan Digital Sky Survey quasars. These are predicted by models of supermassive BH and host galaxy coevolution, therefore their census and population properties constitute an important test of these models. In our working hypothesis, one of the two BHs accretes at a much higher rate than the other and carries with it the only broad emission line region of the system, making the system analogous to a single-lined spectroscopic binary star. Accordingly, we used spectroscopic principal component analysis to search for broad Hβ emission lines that are displaced from the quasar rest frame by |Δ v| >~ 1000 km s-1. This method also yields candidates for rapidly recoiling BHs. Of the 88 candidates, several were previously reported in the literature. We found a correlation between the peak offset and skewness of the broad Hβ profiles, suggesting a common physical explanation for these profiles. We carried out follow-up spectroscopic observations of 68 objects to search for changes in the peak velocities of the Hβ lines. We measured statistically significant changes in 14 objects, with implied accelerations between -120 and +120 km s-1 yr-1. Interpreting the offset broad emission lines as signatures of supermassive binaries is subject to many caveats. Many more follow-up observations over a long temporal baseline are needed to characterize the variability pattern of the broad lines and test that it is consistent with orbital motion. The possibility that some of the objects in this sample are rapidly recoiling BHs remains open.

  3. Tracing non-conservative mass transfer eras in close binaries from observed period variations

    NASA Astrophysics Data System (ADS)

    Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.

    2013-09-01

    The pure information directly taken from the observed orbital evolution of eclipsing binary stars (centuries at most) is valuable for the study of many important physical mechanisms related to the stellar structure. Especially in the case of eclipsing binary systems, this may happen by monitoring their eclipse timing variations, i.e. by means of an O-C diagram analysis. As long as a binary system attains a semi-detached configuration, material begins to flow from the component that fills its Roche lobe toward its mate through the first Lagrangian (L1) point. Here, we examine two non conservative mass transfer (MT) paths. The MT process is then accompanied by mass and angular momentum loss from the system. In the first path, angular momentum is removed through a hot spot which re-emits part of the incoming material, and in the second, angular momentum is carried away via an outer Lagrangian point (L2/L3) due to the small accumulating efficiency of the accretion disk surrounding the gainer. Dealing with the less massive component as the donor in the latter path, it is shown that there is always a critical mass ratio over which the period is expected to decrease, contrary to what the fully conservative MT predicts. Consistent with our expectations, the critical values become progressively smaller as the degree of liberalism is gradually widened. The O-C diagram of several semi-detached systems, expecting to experience a liberal era, is individually examined aiming to estimate both the mass transfer and the mass loss rate.

  4. A study of the reflection effect in close spectroscopic binary stars

    NASA Technical Reports Server (NTRS)

    Chen, K.-Y.; Rhein, W. J.

    1973-01-01

    Four W Ursae Majoris-type binaries were investigated using the simple model of blackbody solid spheres. Numerical computations were carried out for the rotationally broadened profiles of spectral lines Sr II (4077.7) and Ca I (4226.7) and the mean radial velocities. These mean velocities at different phases outside eclipses were compared with sinusoidal values of the radial velocity curve for point masses. Within the present accuracy of observations, the reflection effect is small and may be neglected in the analysis of radial velocity curves.

  5. A close-pair binary in a distant triple supermassive black hole system.

    PubMed

    Deane, R P; Paragi, Z; Jarvis, M J; Coriat, M; Bernardi, G; Fender, R P; Frey, S; Heywood, I; Klöckner, H-R; Grainge, K; Rumsey, C

    2014-07-01

    Galaxies are believed to evolve through merging, which should lead to some hosting multiple supermassive black holes. There are four known triple black hole systems, with the closest black hole pair being 2.4 kiloparsecs apart (the third component in this system is at 3 kiloparsecs), which is far from the gravitational sphere of influence (about 100 parsecs for a black hole with mass one billion times that of the Sun). Previous searches for compact black hole systems concluded that they were rare, with the tightest binary system having a separation of 7 parsecs (ref. 10). Here we report observations of a triple black hole system at redshift z = 0.39, with the closest pair separated by about 140 parsecs and significantly more distant from Earth than any other known binary of comparable orbital separation. The effect of the tight pair is to introduce a rotationally symmetric helical modulation on the structure of the large-scale radio jets, which provides a useful way to search for other tight pairs without needing extremely high resolution observations. As we found this tight pair after searching only six galaxies, we conclude that tight pairs are more common than hitherto believed, which is an important observational constraint for low-frequency gravitational wave experiments. PMID:24990745

  6. A close-pair binary in a distant triple supermassive black hole system.

    PubMed

    Deane, R P; Paragi, Z; Jarvis, M J; Coriat, M; Bernardi, G; Fender, R P; Frey, S; Heywood, I; Klöckner, H-R; Grainge, K; Rumsey, C

    2014-07-01

    Galaxies are believed to evolve through merging, which should lead to some hosting multiple supermassive black holes. There are four known triple black hole systems, with the closest black hole pair being 2.4 kiloparsecs apart (the third component in this system is at 3 kiloparsecs), which is far from the gravitational sphere of influence (about 100 parsecs for a black hole with mass one billion times that of the Sun). Previous searches for compact black hole systems concluded that they were rare, with the tightest binary system having a separation of 7 parsecs (ref. 10). Here we report observations of a triple black hole system at redshift z = 0.39, with the closest pair separated by about 140 parsecs and significantly more distant from Earth than any other known binary of comparable orbital separation. The effect of the tight pair is to introduce a rotationally symmetric helical modulation on the structure of the large-scale radio jets, which provides a useful way to search for other tight pairs without needing extremely high resolution observations. As we found this tight pair after searching only six galaxies, we conclude that tight pairs are more common than hitherto believed, which is an important observational constraint for low-frequency gravitational wave experiments.

  7. The Nature of the cm-mm Emission in Close Wolf-Rayet Binaries

    NASA Astrophysics Data System (ADS)

    Montes, G.; Alberdi, A.; Pérez-Torres, M. A.; González, R. F.

    2015-10-01

    The centimeter spectra of Wolf-Rayet (WR) binaries often show a contribution from a wind-wind collision region (WCR) between the stars. In short period systems (≤sssim 1 yr), such a component is expected to be absorbed by the unshocked winds, losing any effect from its binarity. Recent studies suggest that the WCR in these systems may also contribute to the emission at both centimeter and millimeter wavelengths. We analyzed and compared centimeter and millimeter observations of a total sample of 17 WR stars (including nine confirmed short-period systems) to detect any possible WCR contribution. More detailed observations are required in order to distinguish between different scenarios. We highlight the importance of analyzing the spectrum from quasi-simultaneous observations in a wide range of frequencies in order to properly characterize and distinguish any possible extra contribution.

  8. HD 314884: a slowly pulsating B star in a close binary

    NASA Astrophysics Data System (ADS)

    Johnson, Christopher B.; Hynes, R. I.; Maccarone, T.; Britt, C. T.; Davis, H.; Jonker, P. G.; Torres, M. A. P.; Steeghs, D.; Greiss, S.; Nelemans, G.

    2014-10-01

    We present the results of a spectroscopic and photometric analysis of HD 314884, a slowly pulsating B star (SPB) in a binary system with detected soft-X-ray emission. We spectrally classify the B star as a B5V-B6V star with Teff = 15 490 ± 310 K, log g = 3.75 ± 0.25 dex, and a photometric period of P0 = 0.889 521(12) d. A spectroscopic period search reveals an orbital period for the system of Porb = 1.3654(11) d. The discrepancy in the two periods and the identification of a second and third distinct frequency in the photometric Fourier transform at P1 = 3.1347(56) and P2 = 1.517(28) d provides evidence that HD 314884 is an SPB with at least three oscillation frequencies. These frequencies appear to originate from higher order, non-linear tidal pulsations. Using the dynamical parameters obtained from the radial-velocity curve, we find the most probable companion mass to be M1 = ˜0.8 M⊙ assuming a typical mass for the B star and most probable inclination. We conclude that the X-ray source companion to HD 314884 is most likely a coronally active G-type star or a white dwarf, with no apparent emission lines in the optical spectrum. The mass probability distribution of the companion star mass spans 0.6-2.3 M⊙ at 99 per cent confidence which allows the possibility of a neutron star companion. The X-ray source is unlikely to be a black hole unless it is of a very low mass or low binary inclination.

  9. A VERY CLOSE BINARY BLACK HOLE IN A GIANT ELLIPTICAL GALAXY 3C 66B AND ITS BLACK HOLE MERGER

    SciTech Connect

    Iguchi, Satoru; Okuda, Takeshi; Sudou, Hiroshi E-mail: okuda@a.phys.nagoya-u.ac.j

    2010-12-01

    Recent observational results provide possible evidence that binary black holes (BBHs) exist in the center of giant galaxies and may merge to form a supermassive black hole in the process of their evolution. We first detected a periodic flux variation on a cycle of 93 {+-} 1 days from the 3 mm monitor observations of a giant elliptical galaxy 3C 66B for which an orbital motion with a period of 1.05 {+-} 0.03 yr had been already observed. The detected signal period being shorter than the orbital period can be explained by taking into consideration the Doppler-shifted modulation due to the orbital motion of a BBH. Assuming that the BBH has a circular orbit and that the jet axis is parallel to the binary angular momentum, our observational results demonstrate the presence of a very close BBH that has a binary orbit with an orbital period of 1.05 {+-} 0.03 yr, an orbital radius of (3.9 {+-} 1.0) x 10{sup -3} pc, an orbital separation of (6.1{sup +1.0} {sub -0.9}) x 10{sup -3} pc, a larger black hole mass of (1.2{sup +0.5} {sub -0.2}) x 10{sup 9} M {sub sun}, and a smaller black hole mass of (7.0{sup +4.7} {sub -6.4}) x 10{sup 8} M {sub sun}. The BBH decay time of (5.1{sup +60.5} {sub -2.5}) x 10{sup 2} yr provides evidence for the occurrence of black hole mergers. This Letter will demonstrate the interesting possibility of black hole collisions to form a supermassive black hole in the process of evolution, one of the most spectacular natural phenomena in the universe.

  10. A possible close supermassive black-hole binary in a quasar with optical periodicity.

    PubMed

    Graham, Matthew J; Djorgovski, S G; Stern, Daniel; Glikman, Eilat; Drake, Andrew J; Mahabal, Ashish A; Donalek, Ciro; Larson, Steve; Christensen, Eric

    2015-02-01

    Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic and can be due to a variety of physical mechanisms; it is also well-described statistically in terms of a damped random walk model. The recent availability of large collections of astronomical time series of flux measurements (light curves) offers new data sets for a systematic exploration of quasar variability. Here we report the detection of a strong, smooth periodic signal in the optical variability of the quasar PG 1302-102 with a mean observed period of 1,884 ± 88 days. It was identified in a search for periodic variability in a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of about 9 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. Such systems are an expected consequence of galaxy mergers and can provide important constraints on models of galaxy formation and evolution.

  11. A possible close supermassive black-hole binary in a quasar with optical periodicity.

    PubMed

    Graham, Matthew J; Djorgovski, S G; Stern, Daniel; Glikman, Eilat; Drake, Andrew J; Mahabal, Ashish A; Donalek, Ciro; Larson, Steve; Christensen, Eric

    2015-02-01

    Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic and can be due to a variety of physical mechanisms; it is also well-described statistically in terms of a damped random walk model. The recent availability of large collections of astronomical time series of flux measurements (light curves) offers new data sets for a systematic exploration of quasar variability. Here we report the detection of a strong, smooth periodic signal in the optical variability of the quasar PG 1302-102 with a mean observed period of 1,884 ± 88 days. It was identified in a search for periodic variability in a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of about 9 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. Such systems are an expected consequence of galaxy mergers and can provide important constraints on models of galaxy formation and evolution. PMID:25561176

  12. THE CLOSE T TAURI BINARY SYSTEM V4046 Sgr: ROTATIONALLY MODULATED X-RAY EMISSION FROM ACCRETION SHOCKS

    SciTech Connect

    Argiroffi, C.; Maggio, A.; Damiani, F.; Montmerle, T.; Huenemoerder, D. P.; Alecian, E.; Audard, M.; Bouvier, J.; Gregory, S. G.; Guedel, M.; Hussain, G. A. J.; Kastner, J. H.; Sacco, G. G.

    2012-06-20

    We report initial results from a quasi-simultaneous X-ray/optical observing campaign targeting V4046 Sgr, a close, synchronous-rotating classical T Tauri star (CTTS) binary in which both components are actively accreting. V4046 Sgr is a strong X-ray source, with the X-rays mainly arising from high-density (n{sub e}{approx} 10{sup 11}-10{sup 12} cm{sup -3}) plasma at temperatures of 3-4 MK. Our multi-wavelength campaign aims to simultaneously constrain the properties of this X-ray-emitting plasma, the large-scale magnetic field, and the accretion geometry. In this paper, we present key results obtained via time-resolved X-ray-grating spectra, gathered in a 360 ks XMM-Newton observation that covered 2.2 system rotations. We find that the emission lines produced by this high-density plasma display periodic flux variations with a measured period, 1.22 {+-} 0.01 d, that is precisely half that of the binary star system (2.42 d). The observed rotational modulation can be explained assuming that the high-density plasma occupies small portions of the stellar surfaces, corotating with the stars, and that the high-density plasma is not azimuthally symmetrically distributed with respect to the rotational axis of each star. These results strongly support models in which high-density, X-ray-emitting CTTS plasma is material heated in accretion shocks, located at the base of accretion flows tied to the system by magnetic field lines.

  13. Smoothed Particle Hydrodynamics: Numerical Techniques and Applications to Accretion Disks in Close Binaries.

    NASA Astrophysics Data System (ADS)

    Simpson, James Charles

    1995-01-01

    collisions the velocity distribution closely matches the exact Maxwell-Boltzmann distribution. The simulated mean free path agrees with the predicted value.

  14. A copula-based closed-form binary logit choice model for accommodating spatial correlation across observational units

    NASA Astrophysics Data System (ADS)

    Bhat, Chandra R.; Sener, Ipek N.

    2009-09-01

    This study focuses on accommodating spatial dependency in data indexed by geographic location. In particular, the emphasis is on accommodating spatial error correlation across observational units in binary discrete choice models. We propose a copula-based approach to spatial dependence modeling based on a spatial logit structure rather than a spatial probit structure. In this approach, the dependence between the logistic error terms of different observational units is directly accommodated using a multivariate logistic distribution based on the Farlie-Gumbel-Morgenstein (FGM) copula. The approach represents a simple and powerful technique that results in a closed-form analytic expression for the joint probability of choice across observational units, and is straightforward to apply using a standard and direct maximum likelihood inference procedure. There is no simulation machinery involved, leading to substantial computation gains relative to current methods to address spatial correlation. The approach is applied to teenagers’ physical activity participation levels, a subject of considerable interest in the public health, transportation, sociology, and adolescence development fields. The results indicate that failing to accommodate heteroscedasticity and spatial correlation can lead to inconsistent and inefficient parameter estimates, as well as incorrect conclusions regarding the elasticity effects of exogenous variables.

  15. On the observed mass distribution of compact stellar remnants in close binary systems and possible interpretations proposed for the time being

    NASA Astrophysics Data System (ADS)

    Sokolov, V. V.

    2016-06-01

    It turns out that accumulation of data during 40-years observational studies just emphasized a contrast between pulsars and black hole (BH) candidates in Galactic close binary stellar systems: (1) the mass spectrum of these degenerate stellar objects (or collapsars) shows an evident absence of objects with masses within the interval from 2M_(Sun) (with a first peak at about 1.4M_(Sun)) to approximately 6M_(Sun), (2) and in close binary stellar systems with a low-massive (about 0.6M_(Sun)) optical companion the most probable mass value (the peak in the mass distribution of BH candidates) turned out to be close to 6.7M_(Sun). This puzzle of discrete mass spectra of collapsars in close binary systems demands some solution and explanation in stellar evolution scenarios in connection with the core-collapse supernovae explosion mechanism and in context of a relation between supernovae and gamma-ray bursts. The collapsar strong field - an analogue of BH in General Relativity - is investigated in a totally non-metric, dynamical model of gravitational interaction theory, in which extremely compact objects of the masses M_Q approx.= 6.7M_(Sun) with a quark-gluon plasma bag of radius r^* = GM_Q/c^2 approx.= 10 km exist.

  16. How Cool Is That? An IRTF/SPEX Spectroscopic Study of the Close Binary T Tauri System V4046 Sgr

    NASA Astrophysics Data System (ADS)

    Smith, Carter-Thaxton; Rapson, V.; Sargent, B. A.; Kastner, J. H.; Rayner, J.

    2014-01-01

    We have obtained near-IR (1-5 micron) spectroscopy of the nearby, close binary T Tauri system V4046 Sgr AB with the NASA Infrared Telescope Facility (IRTF) SPEX spectrometer. Our motivation is to assess the potential discrepancies between optical and near-IR spectral classifications of this and other young, late-type stars. Such (optical vs. near-IR) spectral type discrepancies have important implications for the application of pre-main sequence (pre-MS) evolutionary tracks to infer the ages and masses of pre-MS stars; V4046 Sgr AB provides an important test case in this regard, due to the stringent constraints on its system mass (a total of ~1.8 Msun, with roughly equal-mass components) that are imposed by interferometic CO imaging of its extended circumbinary disk combined with its relatively well-determined age 12 Myr) and distance 73 pc). We performed equivalent width measurements of diagnostic absorption lines and broad scaling relation measurements to facilitate comparisons between our SPEX near-IR observations and those of IRTF spectral standards. Our preliminary results point to a composite near-IR spectral type for V4046 Sgr AB that is later than the (mid-K) type previously determined from optical spectroscopy. This discrepancy is consistent with that found for other T Tauri stars (most notably, for TW Hya), emphasizing the need for caution in relying on a specific wavelength regime to obtain pre-MS stellar spectral classifications and (hence) determinations of pre-MS age and mass. Support for this research is provided by by National Science Foundation grant AST-1108950 to RIT C.T. Smith's research at RIT was supported by a NSF Research Experience for Undergraduates program grant to RIT's Chester F. Carlson Center for Imaging Science.

  17. THE MASS-LOSS-INDUCED ECCENTRIC KOZAI MECHANISM: A NEW CHANNEL FOR THE PRODUCTION OF CLOSE COMPACT OBJECT-STELLAR BINARIES

    SciTech Connect

    Shappee, Benjamin J.; Thompson, Todd A. E-mail: thompson@astronomy.ohio-state.edu

    2013-03-20

    Over a broad range of initial inclinations and eccentricities, an appreciable fraction of hierarchical triple star systems with similar masses are essentially unaffected by the Kozai-Lidov mechanism (KM) until the primary in the central binary evolves into a compact object. Once it does, it may be much less massive than the other components in the ternary, enabling the 'eccentric Kozai mechanism (EKM)': the mutual inclination between the inner and outer binaries can flip signs driving the inner binary to very high eccentricity, leading to a close binary or collision. We demonstrate this 'mass-loss-induced eccentric Kozai' (MIEK) mechanism by considering an example system and defining an ad hoc minimal separation between the inner two members at which tidal effects become important. For fixed initial masses and semimajor axes, but uniform distributions of eccentricity and cosine of the mutual inclination, {approx}10% of systems interact tidally or collide while the primary is on the main sequence (MS) due to the KM or EKM. Those affected by the EKM are not captured by earlier quadrupole-order secular calculations. We show that fully {approx}30% of systems interact tidally or collide for the first time as the primary swells to AU scales, mostly as a result of the KM. Finally, {approx}2% of systems interact tidally or collide for the first time after the primary sheds most of its mass and becomes a white dwarf (WD), mostly as a result of the MIEK mechanism. These findings motivate a more detailed study of mass loss in triple systems and the formation of close neutron star (NS)/WD-MS and NS/WD-NS/WD binaries without an initial common envelope phase.

  18. SDSS J001641-000925: THE FIRST STABLE RED DWARF CONTACT BINARY WITH A CLOSE-IN STELLAR COMPANION

    SciTech Connect

    Qian, S.-B.; Jiang, L.-Q.; Zhu, L.-Y.; Zhao, E. G.; He, J.-J.; Liao, W.-P.; Wang, J.-J.; Liu, L.; Zhou, X.; Liu, N. P.; Fernández Lajús, E.; Soonthornthum, B.; Rattanasoon, S.; Aukkaravittayapun, S.

    2015-01-10

    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-dot ∼8 s yr{sup −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 {sub 3}sin i' ∼ 0.14 M {sub ☉}. The orbital separation between the third body and the central binary is about 2.8 AU. 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.

  19. The chemical evolution of the secondary stars in close binaries, arising from common-envelope evolution and nova outbursts

    NASA Astrophysics Data System (ADS)

    Marks, P. B.; Sarna, M. J.

    1998-12-01

    Using a Paczynski-type stellar evolution code, we have modelled the evolution of secondary stars through the common-envelope and semidetached phases of close binary evolution. Our calculations are aimed at determining the effects of the accretion of red giant envelope material during the common-envelope phase, and the accretion of novae ejecta during the semidetached phase, on the surface composition of the secondary. For the second case, we make use of the results of the calculations of Prialnik & Kovetz, Kovetz & Prialnik and Prialnik, which concern the effects of accretion on to carbon-oxygen white dwarfs with varying white dwarf mass, white dwarf central temperature and mass transfer rate (the defining characteristics of nova outburst behaviour). In this paper we present the results of our calculations of a large grid of models designed to test the effects of these two polluting processes, both individually and together. We find that both processes may significantly affect the surface composition of the secondary, and that in the case of the accretion of novae ejecta, thermohaline mixing is extremely important and cannot be neglected. Our results indicate four phases in the evolution of the surface composition of the secondary during semidetached evolution: (i) the material accreted during the common-envelope phase and that accreted from the novae ejecta are mixed by convection and thermohaline mixing and dominate the surface composition of the secondary; (ii) the material accreted during common-envelope evolution is lost through mass transfer and the surface composition of the secondary is dominated by material accreted from the novae ejecta, which is mixed with the underlying layers of the secondary by convection and thermohaline mixing; (iii) the surface convection zone of the secondary penetrates to deeper layers so that these deeper layers dominate the surface composition of the secondary and thermohaline mixing no longer operates; and (iv) for evolved

  20. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars.

  1. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars. PMID:17749544

  2. Partial port-closing strategy for obtaining high throughput or high purities in a four-zone simulated moving bed chromatography for binary separation.

    PubMed

    Mun, Sungyong

    2010-10-15

    The "partial port-closing" operation strategy for a four-zone simulated moving bed (SMB) chromatographic process for binary separation was developed to improve the SMB performance. This strategy included the partial extract-closing (PEC) and the partial raffinate-closing (PRC) operations. In case of the PEC operation, the extract port is made to be closed during the first-half stage of a switching period. During the latter-half stage, the extract port is made to be open. In case of the PRC operation, the raffinate port is made to be open during the first-half stage of a switching period. During the latter-half stage, the raffinate port is made to be closed. If the operating conditions are chosen properly in each operation using a highly efficient optimization tool, the product stream can be collected during only the period that the product is almost separated from impurity. During the other period that the product is contaminated with impurity, the collection of the product stream can be stopped by closing the product port. The uncollected product stream is then allowed to keep migrating through the adjacent zone within the SMB process. Such a partial port-closing operation including PEC and PRC was found to surpass a conventional SMB operation remarkably in throughput and product purity. PMID:20837353

  3. Models for the evolution of close binaries with He-star and white dwarf components towards Type Ia supernova explosions

    NASA Astrophysics Data System (ADS)

    Neunteufel, P.; Yoon, S.-C.; Langer, N.

    2016-05-01

    Context. Type Ia supernovae (SNe Ia) have been an important tool for astronomy for quite some time; however, the nature of their progenitors remains somewhat mysterious. Recent theoretical studies indicated the possibility of producing thermonuclear detonations of carbon-oxygen white dwarfs (CO WDs) at masses less than the Chandrasekhar mass through accretion of helium-rich matter, which would, depending on mass accretion rate, mass, and initial temperature of the WD, spectrally resemble either a normal SN Ia or a peculiar one. Aims: This study aims to further resolve the state of binary systems comprised of a sub-Chandrasekhar-mass CO WD and a helium star at the point where an accretion-induced detonation occurs and constrains the part of the initial parameter space where this kind of phenomenon is possible. Methods: Preexisting data obtained through simulations of single, constantly accreting CO WDs is used as an indicator for the behavior of new binary models in which the WD is treated as a point mass and which include the non-degenerate partner as a fully resolved stellar model. We parameterize the ignition of the accumulated helium layer, changes in the WD temperature, and changes in the CO core mass depending on the mass transfer rate. Results: The initial conditions allowing for detonation do not form a single contiguous area in the parameter space, whose shape is profoundly influenced by the behavior of the donor star. Mass loss due to Nova outbursts acts in favor of detonation. According to our criteria, about 10% of the detonations in this study can be expected to show spectra consistent with ordinary SNe Ia; the rest exhibit peculiar features.

  4. GSC 07396-00759 = V4046 Sgr C[D]: A WIDE-SEPARATION COMPANION TO THE CLOSE T TAURI BINARY SYSTEM V4046 Sgr AB

    SciTech Connect

    Kastner, J. H.; Sacco, G. G.; Montez, R.; Shi, H.; Huenemoerder, D. P.; Alecian, E.; Argiroffi, C.; Audard, M.; Bouvier, J.; Donati, J.-F.; Gregory, S. G.; Guedel, M.; Hussain, G. A. J.; Montmerle, T.

    2011-10-10

    We explore the possibility that GSC 07396-00759 (spectral type M1e) is a widely separated ({approx}2.'82, or projected separation {approx}12,350 AU) companion to the 'old' (age {approx}12 Myr) classical T Tauri binary system V4046 Sgr AB, as suggested by the proximity and similar space motions of the two systems. If the two systems are equidistant and coeval, then GSC 07396-00759, like V4046 Sgr AB, must be a spectroscopic binary with nearly equal-mass components, and V4046 Sgr must be at least {approx}8 Myr old. Analysis of a serendipitous Chandra X-ray grating spectrum and light curve as well as XMM-Newton light curves and CCD spectra of GSC 07396-00759 obtained during long exposures targeting V4046 Sgr AB reveals a relatively hard (T{sub X} {approx} 10{sup 7} K) X-ray spectrum, strong flaring, and relatively low-density plasma. These X-ray characteristics of GCS 07396-00759 are indicative of a high level of coronal activity, consistent with its apparent weak-lined T Tauri star status. Interactions between V4046 Sgr AB and GCS 07396-00759 when the two systems were more closely bound may be responsible for (1) their dissolution {approx}10{sup 6} yr ago, (2) the present tight, circular orbit of V4046 Sgr AB, and (3) the persistence of the gaseous circumbinary disk still orbiting V4046 Sgr AB.

  5. Understanding the Unusual X-Ray Emission Properties of the Massive, Close Binary WR 20a: A High Energy Window into the Stellar Wind Initiation Region

    NASA Astrophysics Data System (ADS)

    Montes, Gabriela; Ramirez-Ruiz, Enrico; De Colle, Fabio; Strickler, Rachel

    2013-11-01

    The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf-Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal which includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a critical test-case for how radiatively driven stellar winds are initiated and how they interact. Our models not only procure a robust description of current Chandra data, which cover the orbital phases between 0.3 and 0.6, but also provide detailed predictions over the entire orbit.

  6. UNDERSTANDING THE UNUSUAL X-RAY EMISSION PROPERTIES OF THE MASSIVE, CLOSE BINARY WR 20a: A HIGH ENERGY WINDOW INTO THE STELLAR WIND INITIATION REGION

    SciTech Connect

    Montes, Gabriela; Ramirez-Ruiz, Enrico; De Colle, Fabio; Strickler, Rachel

    2013-11-10

    The problem of explaining the X-ray emission properties of the massive, close binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR 20a is composed of two nearly identical Wolf-Rayet stars of 82 and 83 solar masses orbiting with a period of only 3.7 days. Although Chandra observations were taken during the secondary optical eclipse, the X-ray light curve shows no signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous and softer during the optical eclipse, opposite to what has been observed in other binary systems. To aid in our interpretation of the data, we compare with the results of hydrodynamical simulations using the adaptive mesh refinement code Mezcal which includes radiative cooling and a radiative acceleration force term. It is shown that the X-ray emission can be successfully explained in models where the wind-wind collision interface in this system occurs while the outflowing material is still being accelerated. Consequently, WR 20a serves as a critical test-case for how radiatively driven stellar winds are initiated and how they interact. Our models not only procure a robust description of current Chandra data, which cover the orbital phases between 0.3 and 0.6, but also provide detailed predictions over the entire orbit.

  7. Radial velocity variable, hot post-AGB stars from the MUCHFUSS project. Classification, atmospheric parameters, formation scenarios

    NASA Astrophysics Data System (ADS)

    Reindl, N.; Geier, S.; Kupfer, T.; Bloemen, S.; Schaffenroth, V.; Heber, U.; Barlow, B. N.; Østensen, R. H.

    2016-03-01

    In the course of the MUCHFUSS project we recently discovered four radial velocity (RV) variable, hot (Teff≈ 80 000-110 000 K) post-asymptotic giant branch (AGB) stars. Among them, we found the first known RV variable O(He) star, the only second known RV variable PG 1159 close binary candidate, as well as the first two naked (i.e., without planetary nebula (PN)) H-rich post-AGB stars of spectral type O(H) that show significant RV variations. We present a non-LTE spectral analysis of these stars along with one further O(H)-type star whose RV variations were found to be not significant. We also report the discovery of a far-infrared excess in the case of the PG 1159 star. None of the stars in our sample displays nebular emission lines, which can be explained well in terms of a very late thermal pulse evolution in the case of the PG 1159 star. The "missing" PNe around the O(H)-type stars seems strange, since we find that several central stars of PNe have much longer post-AGB times. Besides the non-ejection of a PN, the occurrence of a late thermal pulse, or the re-accretion of the PN in the previous post-AGB evolution offer possible explanations for those stars not harbouring a PN (anymore). In the case of the O(He) star J0757, we speculate that it might have been previously part of a compact He transferring binary system. In this scenario, the mass transfer must have stopped after a certain time, leaving behind a low-mass close companion that may be responsible for the extreme RV shift of 107.0 ± 22.0 km s-1 that was measured within only 31 min.

  8. Supersoft sources in XMM-Newton Small Magellanic Cloud fields. A symbiotic and a close binary or cooling neutron star

    NASA Astrophysics Data System (ADS)

    Kahabka, P.; Haberl, F.

    2006-06-01

    We report the detection and study of two faint ROSAT supersoft X-ray sources in the SMC field with XMM-Newton, RX J0059.1-7505 and RX J0059.4-7118. Due to the larger effective area of XMM-Newton we can constrain the X-ray spectra of both sources. RX J0059.1-7505 is optically identified with the symbiotic LIN 358 in the SMC. A 20 eV blackbody component dominates the observed spectrum. The soft blackbody component is consistent with steady nuclear burning in a shell although the spectrum is more complex than a simple blackbody continuum. RX J0059.4-7118 is not optically identified and we derive with the Optical Monitor (OM) a V magnitude ⪆19.3 assuming an M0 spectral type. The X-ray spectrum is fitted with a blackbody component with a temperature of 90 eV and an additional spectrally hard component which can be reproduced with a powerlaw. The luminosity of RX J0059.4-7118 would be 4 × 1034 erg s-1 at the distance of the SMC. This is too large for a Cataclysmic Variable (CV). The spectral appearance is not in agreement with a supersoft source in the SMC. Thus we suggest that RX J0059.4-7118 is a Galactic source. As the optical magnitude derived from the OM data may be too faint for a normal Galactic CV we examined the possibility that RX J0059.4-7118 is a polar CV in the Galaxy, an isolated cooling neutron star (INS) at distance (1{-}2) kpc, a pulsar with a brown dwarf companion, or a Galactic quiescent low-mass X-ray binary (qLMXB). We favor the hypothesis of a Galactic CV because of variability in the EPIC-pn data with a timescale of 1 h. A third supersoft ROSAT source, RX J0050.5-7455, is not detected with XMM-Newton.

  9. Ultraviolet observations of close-binary and pulsating nuclei of planetary nebulae; Winds and shells around low-mass supergiants; The close-binary nucleus of the planetary nebula HFG-1; A search for binary nuclei of planetary nebulae; UV monitoring of irregularly variable planetary nuclei; and The pulsating nucleus of the planetary nebula Lo 4

    NASA Technical Reports Server (NTRS)

    Bond, Howard E.

    1992-01-01

    A brief summary of the research highlights is presented. The topics covered include the following: binary nuclei of planetary nebulae; other variable planetary nuclei; low-mass supergiants; and other IUE-related research.

  10. Radio Emission and Orbital Motion from the Close-encounter Star–Brown Dwarf Binary WISE J072003.20–084651.2

    NASA Astrophysics Data System (ADS)

    Burgasser, Adam J.; Melis, Carl; Todd, Jacob; Gelino, Christopher R.; Hallinan, Gregg; Bardalez Gagliuffi, Daniella

    2015-12-01

    We report the detection of radio emission and orbital motion from the nearby star–brown dwarf binary WISE J072003.20–084651.2AB. Radio observations across the 4.5–6.5 GHz band with the Very Large Array identify at the position of the system quiescent emission with a flux density of 15 ± 3 μJy, and a highly polarized radio source that underwent a 2–3 minute burst with peak flux density 300 ± 90 μJy. The latter emission is likely a low-level magnetic flare similar to optical flares previously observed for this source. No outbursts were detected in separate narrow-band Hα monitoring observations. We report new high-resolution imaging and spectroscopic observations that confirm the presence of a co-moving T5.5 secondary and provide the first indications of three-dimensional orbital motion. We used these data to revise our estimates for the orbital period (4.1{}-1.3+2.7 year) and tightly constrain the orbital inclination to be nearly edge-on (93.°6+1.°6‑1.°4), although robust measures of the component and system masses will require further monitoring. The inferred orbital motion does not change the high likelihood that this radio-emitting very low-mass binary made a close pass to the Sun in the past 100 kyr. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  11. The number of O-type runaways, the number of O and Wolf-Rayet stars with a compact companion and the formation rate of double pulsars predicted by massive close binary evolution.

    NASA Astrophysics Data System (ADS)

    De Donder, E.; Vanbeveren, D.; van Bever, J.

    1997-02-01

    Using a detailed model of massive close binary evolution and accounting properly for the effects of asymmetric supernova explosions (SN) where we use recent observations of pulsar runaway velocities, we determine the theoretically expected number of post-SN O-type stars with and without a compact companion (CC), the number of O-type runaways, the number of WR+CC systems and the formation rate of binary pulsars in our Galaxy. We conclude that o at least 50% of the O-type runaways are formed through the binary scenario, o less than 3% of all WR stars may hide a CC, o the formation rate of binary pulsars in our Galaxy =~0.003-0.01 times the formation rate of massive stars; this corresponds roughly to a binary pulsar formation rate of the order of 10^-5^/year in agreement with the observations. Our results reveal a significant fraction of single WR stars but with a binary history. We also predict the existence of 'weird' WR stars, i.e a WR star with a CC in its centre (descendants of Thorne-˙(Z)ytkow objects).

  12. THE CHROMOSPHERIC ACTIVITY OF [HH97] FS Aur-79: A CLOSE BINARY WITH LATE-TYPE ACTIVE (dK7e+dM3e) COMPONENTS

    SciTech Connect

    Austin, S. J.; Robertson, J. W.; De Souza, T. R.; Tycner, C.; Honeycutt, R. K. E-mail: jrobertson@atu.edu E-mail: c.tycner@cmich.edu

    2011-04-15

    Using Doppler tomography we show that FS Aur-79, a near-contact close binary system with late-type active dK7e+dM3e components, has chromospheric prominences in two distinct emission regions associated with the primary star and a larger amount of chromospheric activity associated with the cooler secondary star. The line profiles, equivalent widths, and equivalent width ratios of the H{alpha} and H{beta} emission lines as a function of orbital phase further support that the majority of the chromospheric emission originates above the secondary star and near the neck region. Analysis of high-resolution spectra using the technique of broadening functions has enabled us to determine the radial velocity of the secondary star near quadratures to be approximately 224 km s{sup -1}. A Wilson-Devinney model of the system fitting the UBV light curves and radial velocities shows that there are star spots near the chromospherically active regions. Finally, the absence of Li I {lambda}6708 in the spectra lets us put a lower limit on the age of this system to at least 500 Myr.

  13. Very Low-mass Stellar and Substellar Companions to Solar-like Stars from MARVELS. VI. A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646

    NASA Astrophysics Data System (ADS)

    Ma, Bo; Ge, Jian; Wolszczan, Alex; Muterspaugh, Matthew W.; Lee, Brian; Henry, Gregory W.; Schneider, Donald P.; Martín, Eduardo L.; Niedzielski, Andrzej; Xie, Jiwei; Fleming, Scott W.; Thomas, Neil; Williamson, Michael; Zhu, Zhaohuan; Agol, Eric; Bizyaev, Dmitry; Nicolaci da Costa, Luiz; Jiang, Peng; Martinez Fiorenzano, A. F.; González Hernández, Jonay I.; Guo, Pengcheng; Grieves, Nolan; Li, Rui; Liu, Jane; Mahadevan, Suvrath; Mazeh, Tsevi; Nguyen, Duy Cuong; Paegert, Martin; Sithajan, Sirinrat; Stassun, Keivan; Thirupathi, Sivarani; van Eyken, Julian C.; Wan, Xiaoke; Wang, Ji; Wisniewski, John P.; Zhao, Bo; Zucker, Shay

    2016-11-01

    We report the detections of a giant planet (MARVELS-7b) and a brown dwarf (BD) candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. To the best of our knowledge, it is the first close binary system with more than one substellar circumprimary companion that has been discovered. The detection of this giant planet was accomplished using the first multi-object Doppler instrument (KeckET) at the Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations using the Exoplanet Tracker at the Kitt Peak National Observatory, the High Resolution Spectrograph at the Hobby Eberley telescope, the “Classic” spectrograph at the Automatic Spectroscopic Telescope at the Fairborn Observatory, and MARVELS from SDSS-III confirmed this giant planet discovery and revealed the existence of a long-period BD in this binary. HD 87646 is a close binary with a separation of ∼22 au between the two stars, estimated using the Hipparcos catalog and our newly acquired AO image from PALAO on the 200 inch Hale Telescope at Palomar. The primary star in the binary, HD 87646A, has {T}{eff} = 5770 ± 80 K, log g = 4.1 ± 0.1, and [Fe/H] = ‑0.17 ± 0.08. The derived minimum masses of the two substellar companions of HD 87646A are 12.4 ± 0.7 {M}{Jup} and 57.0 ± 3.7 {M}{Jup}. The periods are 13.481 ± 0.001 days and 674 ± 4 days and the measured eccentricities are 0.05 ± 0.02 and 0.50 ± 0.02 respectively. Our dynamical simulations show that the system is stable if the binary orbit has a large semimajor axis and a low eccentricity, which can be verified with future astrometry observations.

  14. High-Entropy Alloys with a Hexagonal Close-Packed Structure Designed by Equi-Atomic Alloy Strategy and Binary Phase Diagrams

    NASA Astrophysics Data System (ADS)

    Takeuchi, Akira; Amiya, Kenji; Wada, Takeshi; Yubuta, Kunio; Zhang, Wei

    2014-10-01

    High-entropy alloys (HEAs) with an atomic arrangement of a hexagonal close-packed (hcp) structure were found in YGdTbDyLu and GdTbDyTmLu alloys as a nearly single hcp phase. The equi-atomic alloy design for HEAs assisted by binary phase diagrams started with selecting constituent elements with the hcp structure at room temperature by permitting allotropic transformation at a high temperature. The binary phase diagrams comprising the elements thus selected were carefully examined for the characteristics of miscibility in both liquid and solid phases as well as in both solids due to allotropic transformation. The miscibility in interest was considerably narrow enough to prevent segregation from taking place during casting around the equi-atomic composition. The alloy design eventually gave candidates of quinary equi-atomic alloys comprising heavy lanthanides principally. The XRD analysis revealed that YGdTbDyLu and GdTbDyTmLu alloys thus designed are formed into the hcp structure in a nearly single phase. It was found that these YGdTbDyLu and GdTbDyTmLu HEAs with an hcp structure have delta parameter ( δ) values of 1.4 and 1.6, respectively, and mixing enthalpy (Δ H mix) = 0 kJ/mol for both alloys. These alloys were consistently plotted in zone S for disordered HEAs in a δ-Δ H mix diagram reported by Zhang et al. (Adv Eng Mater 10:534, 2008). The value of valence electron concentration of the alloys was evaluated to be 3 as the first report for HEAs with an hcp structure. The finding of HEAs with the hcp structure is significant in that HEAs have been extended to covering all three simple metallic crystalline structures ultimately followed by the body- and face-centered cubic (bcc and fcc) phases and to all four simple solid solutions that contain the glassy phase from high-entropy bulk metallic glasses.

  15. Binary Planets

    NASA Astrophysics Data System (ADS)

    Ryan, Keegan; Nakajima, Miki; Stevenson, David J.

    2014-11-01

    Can a bound pair of similar mass terrestrial planets exist? We are interested here in bodies with a mass ratio of ~ 3:1 or less (so Pluto/Charon or Earth/Moon do not qualify) and we do not regard the absence of any such discoveries in the Kepler data set to be significant since the tidal decay and merger of a close binary is prohibitively fast well inside of 1AU. SPH simulations of equal mass “Earths” were carried out to seek an answer to this question, assuming encounters that were only slightly more energetic than parabolic (zero energy). We were interested in whether the collision or near collision of two similar mass bodies would lead to a binary in which the two bodies remain largely intact, effectively a tidal capture hypothesis though with the tidal distortion being very large. Necessarily, the angular momentum of such an encounter will lead to bodies separated by only a few planetary radii if capture occurs. Consistent with previous work, mostly by Canup, we find that most impacts are disruptive, leading to a dominant mass body surrounded by a disk from which a secondary forms whose mass is small compared to the primary, hence not a binary planet by our adopted definition. However, larger impact parameter “kissing” collisions were found to produce binaries because the dissipation upon first encounter was sufficient to provide a bound orbit that was then rung down by tides to an end state where the planets are only a few planetary radii apart. The long computational times for these simulation make it difficult to fully map the phase space of encounters for which this outcome is likely but the indications are that the probability is not vanishingly small and since planetary encounters are a plausible part of planet formation, we expect binary planets to exist and be a non-negligible fraction of the larger orbital radius exoplanets awaiting discovery.

  16. XMM-Newton Monitoring of the Close Pre-main-sequence Binary AK Sco. Evidence of Tide-driven Filling of the Inner Gap in the Circumbinary Disk

    NASA Astrophysics Data System (ADS)

    Gómez de Castro, Ana I.; López-Santiago, Javier; Talavera, Antonio; Sytov, A. Yu.; Bisikalo, D.

    2013-03-01

    AK Sco stands out among pre-main-sequence binaries because of its prominent ultraviolet excess, the high eccentricity of its orbit, and the strong tides driven by it. AK Sco consists of two F5-type stars that get as close as 11 R * at periastron passage. The presence of a dense (ne ~ 1011 cm-3) extended envelope has been unveiled recently. In this article, we report the results from an XMM-Newton-based monitoring of the system. We show that at periastron, X-ray and UV fluxes are enhanced by a factor of ~3 with respect to the apastron values. The X-ray radiation is produced in an optically thin plasma with T ~ 6.4 × 106 K and it is found that the N H column density rises from 0.35 × 1021 cm-2 at periastron to 1.11 × 1021 cm-2 at apastron, in good agreement with previous polarimetric observations. The UV emission detected in the Optical Monitor band seems to be caused by the reprocessing of the high-energy magnetospheric radiation on the circumstellar material. Further evidence of the strong magnetospheric disturbances is provided by the detection of line broadening of 278.7 km s-1 in the N V line with Hubble Space Telescope/Space Telescope Imaging Spectrograph. Numerical simulations of the mass flow from the circumbinary disk to the components have been carried out. They provide a consistent scenario with which to interpret AK Sco observations. We show that the eccentric orbit acts like a gravitational piston. At apastron, matter is dragged efficiently from the inner disk border, filling the inner gap and producing accretion streams that end as ring-like structures around each component of the system. At periastron, the ring-like structures come into contact, leading to angular momentum loss, and thus producing an accretion outburst.

  17. XMM-NEWTON MONITORING OF THE CLOSE PRE-MAIN-SEQUENCE BINARY AK SCO. EVIDENCE OF TIDE-DRIVEN FILLING OF THE INNER GAP IN THE CIRCUMBINARY DISK

    SciTech Connect

    Gomez de Castro, Ana Ines; Lopez-Santiago, Javier; Talavera, Antonio; Sytov, A. Yu.; Bisikalo, D.

    2013-03-20

    AK Sco stands out among pre-main-sequence binaries because of its prominent ultraviolet excess, the high eccentricity of its orbit, and the strong tides driven by it. AK Sco consists of two F5-type stars that get as close as 11 R{sub *} at periastron passage. The presence of a dense (n{sub e} {approx} 10{sup 11} cm{sup -3}) extended envelope has been unveiled recently. In this article, we report the results from an XMM-Newton-based monitoring of the system. We show that at periastron, X-ray and UV fluxes are enhanced by a factor of {approx}3 with respect to the apastron values. The X-ray radiation is produced in an optically thin plasma with T {approx} 6.4 Multiplication-Sign 10{sup 6} K and it is found that the N{sub H} column density rises from 0.35 Multiplication-Sign 10{sup 21} cm{sup -2} at periastron to 1.11 Multiplication-Sign 10{sup 21} cm{sup -2} at apastron, in good agreement with previous polarimetric observations. The UV emission detected in the Optical Monitor band seems to be caused by the reprocessing of the high-energy magnetospheric radiation on the circumstellar material. Further evidence of the strong magnetospheric disturbances is provided by the detection of line broadening of 278.7 km s{sup -1} in the N V line with Hubble Space Telescope/Space Telescope Imaging Spectrograph. Numerical simulations of the mass flow from the circumbinary disk to the components have been carried out. They provide a consistent scenario with which to interpret AK Sco observations. We show that the eccentric orbit acts like a gravitational piston. At apastron, matter is dragged efficiently from the inner disk border, filling the inner gap and producing accretion streams that end as ring-like structures around each component of the system. At periastron, the ring-like structures come into contact, leading to angular momentum loss, and thus producing an accretion outburst.

  18. Topologically close-packed phases in binary transition-metal compounds: matching high-throughput ab initio calculations to an empirical structure map

    NASA Astrophysics Data System (ADS)

    Hammerschmidt, T.; Bialon, A. F.; Pettifor, D. G.; Drautz, R.

    2013-11-01

    In steels and single-crystal superalloys the control of the formation of topologically close-packed (TCP) phases is critical for the performance of the material. The structural stability of TCP phases in multi-component transition-metal alloys may be rationalized in terms of the average valence-electron count \\bar {N} and the composition-dependent relative volume-difference \\overline {\\Delta V/V} . We elucidate the interplay of these factors by comparing density-functional theory calculations to an empirical structure map based on experimental data. In particular, we calculate the heat of formation for the TCP phases A15, C14, C15, C36, χ, μ and σ for all possible binary occupations of the Wyckoff positions. We discuss the isovalent systems V/Nb-Ta to highlight the role of atomic-size difference and observe the expected stabilization of C14/C15/C36/μ by \\overline {\\Delta V/V} at ΔN = 0 in V-Ta. In the systems V/Nb-Re, we focus on the well-known trend of A15 → σ → χ stability with increasing \\bar {N} and show that the influence of \\overline {\\Delta V/V} is too weak to stabilize C14/C15/C36/μ in Nb-Re. As an example for a significant influence of both \\bar {N} and \\overline {\\Delta V/V} , we also consider the systems Cr/Mo-Co. Here the sequence A15 → σ → χ is observed in both systems but in Mo-Co the large size-mismatch stabilizes C14/C15/C36/μ. We also include V/Nb-Co that cover the entire valence range of TCP stability and also show the stabilization of C14/C15/C36/μ. Moreover, the combination of a large volume-difference with a large mismatch in valence-electron count reduces the stability of the A15/σ/χ phases in Nb-Co as compared to V-Co. By comparison to non-magnetic calculations we also find that magnetism is of minor importance for the structural stability of TCP phases in Cr/Mo-Co and in V/Nb-Co.

  19. New photometric investigation of the Herbig Ae/Be star HD 52721, a close binary system: Evidence for the existence of large-scale azimuthal inhomogeneities

    NASA Astrophysics Data System (ADS)

    Pavlovskiy, S. E.; Pogodin, M. A.; Kupriyanov, V. V.; Gorshanov, D. L.

    2015-06-01

    We present new results of our photometry for the Herbig Be star HD 52721 obtained from January 16 to March 25, 2013. A new data reduction technique is used. Using this technique, we have also reanalyzed the previous results of our photometry for this object pertaining to the period from March 7 to March 28, 2010. The Be star HD 52721 is known as an eclipsing variable with the period P = 1d. 610. Two photometric minima observed during one period are a peculiarity of its photometric variability. They are separated in phase of the period P by 0.5 and differ from one another in depth by 0 m . 04. We have also detected additional minima observed at the phases of maximum brightness. We hypothesize that they can be associated with the existence of local azimuthal inhomogeneities rotating synchronously with the orbital motion of the binary component stars in the circumstellar envelope. When processing our CCD frames, we have applied an efficient CCD-frame rejection method that has allowed the accuracy of observations to be increased considerably. The CCD frames have been further processed using the Apex II software package, which is a universal software platform for astronomical image processing. We justify the need for additional photometric observations of HD 52721 in various color bands to confirm the hypothesis about the existence of azimuthal inhomogeneities in the program binary system and to analyze their physical properties.

  20. KEPLER ECLIPSING BINARIES WITH STELLAR COMPANIONS

    SciTech Connect

    Gies, D. R.; Matson, R. A.; Guo, Z.; Lester, K. V.; Orosz, J. A.; Peters, G. J. E-mail: rmatson@chara.gsu.edu E-mail: lester@chara.gsu.edu E-mail: gjpeters@mucen.usc.edu

    2015-12-15

    Many short-period binary stars have distant orbiting companions that have played a role in driving the binary components into close separation. Indirect detection of a tertiary star is possible by measuring apparent changes in eclipse times of eclipsing binaries as the binary orbits the common center of mass. Here we present an analysis of the eclipse timings of 41 eclipsing binaries observed throughout the NASA Kepler mission of long duration and precise photometry. This subset of binaries is characterized by relatively deep and frequent eclipses of both stellar components. We present preliminary orbital elements for seven probable triple stars among this sample, and we discuss apparent period changes in seven additional eclipsing binaries that may be related to motion about a tertiary in a long period orbit. The results will be used in ongoing investigations of the spectra and light curves of these binaries for further evidence of the presence of third stars.

  1. ON THE NATURE OF THE HERBIG B[e] STAR BINARY SYSTEM V921 SCORPII: DISCOVERY OF A CLOSE COMPANION AND RELATION TO THE LARGE-SCALE BIPOLAR NEBULA

    SciTech Connect

    Kraus, Stefan; Calvet, Nuria; Hartmann, Lee; Monnier, John D.; Hofmann, Karl-Heinz; Kreplin, Alexander; Weigelt, Gerd

    2012-02-10

    Belonging to the group of B[e] stars, V921 Scorpii is associated with a strong infrared excess and permitted and forbidden line emission, indicating the presence of low- and high-density circumstellar gas and dust. Many aspects of V921 Sco and other B[e] stars still remain mysterious, including their evolutionary state and the physical conditions resulting in the class-defining characteristics. In this Letter, we employ Very Large Telescope Interferometer/AMBER spectro-interferometry in order to reconstruct high-resolution ({lambda}/2B = 0.''0013) model-independent interferometric images for three wavelength bands around 1.65, 2.0, and 2.3 {mu}m. In our images, we discover a close (25.0 {+-} 0.8 mas, corresponding to {approx}29 {+-} 0.9 AU at 1.15 kpc) companion around V921 Sco. Between two epochs in 2008 and 2009, we measure orbital motion of {approx}7 Degree-Sign , implying an orbital period of {approx}35 years (for a circular orbit). Around the primary star, we detect a disk-like structure with indications for a radial temperature gradient. The polar axis of this AU-scale disk is aligned with the arcminute-scale bipolar nebula in which V921 Sco is embedded. Using Magellan/IMACS imaging, we detect multi-layered arc-shaped substructure in the nebula, suggesting episodic outflow activity from the system with a period of {approx}25 years, roughly matching the estimated orbital period of the companion. Our study supports the hypothesis that the B[e] phenomenon is related to dynamical interaction in a close binary system.

  2. Division V: Commission 42: Close Binaries

    NASA Astrophysics Data System (ADS)

    Ribas, Ignasi; Richards, Mercedes T.; Rucinski, Slavek; Bradstreet, David H.; Harmanec, Petr; Kaluzny, Janusz; Mikolajewska, Joanna; Munari, Ulisse; Niarchos, Panagiotis; Olah, Katalin; Pribulla, Theodor; Scarfe, Colin D.; Torres, Guillermo

    2015-08-01

    Commission 42 (C42) co-organized, together with Commission 27 (C27) and Division V (Div V) as a whole, a full day of science and business sessions that were held on 24 August 2012. The program included time slots for discussion of business matters related to Div V, C27 and C42, and two sessions of 2 hours each devoted to science talks of interest to both C42 and C27. In addition, we had a joint session between Div IV and Div V motivated by the proposal to reformulate the division structure of the IAU and the possible merger of the two divisions into a new Div G. The current report gives an account of the matters discussed during the business session of C42.

  3. UHE particle production in close binary systems

    NASA Technical Reports Server (NTRS)

    Hillas, A. M.

    1985-01-01

    Cygnus X-3 appears to generate so much power in the form of charged particles of up to approx 10 to the 17th power eV that the galaxy may need approx 1 such source on average to maintain its flux of ultra high energy cosmic rays. Accreting gas must supply the energy, and in a surprisingly ordered form, if it is correct to use a Vest-rand-Eichler model for radiation of gammas, modified by the introduction of an accretion wake. Certain relationships between 10 to the 12th power eV and 10 to the 15th power gamma rays are expected.

  4. A spectrum synthesis program for binary stars

    NASA Technical Reports Server (NTRS)

    Linnell, Albert P.; Hubeny, Ivan

    1994-01-01

    A new program produces synthetic spectra of binary stars at arbitrary values of orbital longitude, including longitudes of partial or complete eclipse. The stellar components may be distorted, either tidally or rotationally, or both. Either or both components may be rotating nonsynchronously. We illustrate the program performance with two cases: EE Peg, an eclipsing binary with small distortion, and SX Aur, an eclipsing binary that is close to contact.

  5. BINARY ASTEROID ENCOUNTERS WITH TERRESTRIAL PLANETS: TIMESCALES AND EFFECTS

    SciTech Connect

    Fang, Julia; Margot, Jean-Luc

    2012-01-15

    Many asteroids that make close encounters with terrestrial planets are in a binary configuration. Here, we calculate the relevant encounter timescales and investigate the effects of encounters on a binary's mutual orbit. We use a combination of analytical and numerical approaches with a wide range of initial conditions. Our test cases include generic binaries with close, moderate, and wide separations, as well as seven well-characterized near-Earth binaries. We find that close approaches (<10 Earth radii) occur for almost all binaries on 1-10 million year timescales. At such distances, our results suggest substantial modifications to a binary's semimajor axis, eccentricity, and inclination, which we quantify. Encounters within 30 Earth radii typically occur on sub-million year timescales and significantly affect the wider binaries. Important processes in the lives of near-Earth binaries, such as tidal and radiative evolution, can be altered or stopped by planetary encounters.

  6. Exoplanets bouncing between binary stars

    NASA Astrophysics Data System (ADS)

    Moeckel, Nickolas; Veras, Dimitri

    2012-05-01

    Exoplanetary systems are found not only among single stars, but also among binaries of widely varying parameters. Binaries with separations of 100-1000 au are prevalent in the solar neighbourhood; at these separations, planet formation around a binary member may largely proceed as if around a single star. During the early dynamical evolution of a planetary system, planet-planet scattering can eject planets from a star's grasp. In a binary, the motion of a planet ejected from one star has effectively entered a restricted three-body system consisting of itself and the two stars, and the equations of motion of the three-body problem will apply as long as the ejected planet remains far from the remaining planets. Depending on its energy, escape from the binary as a whole may be impossible or delayed until the three-body approximation breaks down, and further close interactions with its planetary siblings boost its energy when it passes close to its parent star. Until then, this planet may be able to transition from the space around one star to the other, and chaotically 'bounce' back and forth. In this paper, we directly simulate scattering planetary systems that are around one member of a circular binary, and quantify the frequency of bouncing in scattered planets. We find that a great majority (70-85 per cent) of ejected planets will pass at least once through the space of it's host's binary companion, and depending on the binary parameters about 35-75 per cent will begin bouncing. The time spent bouncing is roughly lognormally distributed with a peak at about 104 yr, with only a small percentage bouncing for more than 1 Myr. This process may perturb and possibly incite instability among existing planets around the companion star. In rare cases, the presence of multiple planets orbiting both stars may cause post-bouncing capture or planetary swapping.

  7. A spectroscopic and photometric study of the planetary nebulae Kn 61 and Pa 5

    SciTech Connect

    García-Díaz, Ma. T.; González-Buitrago, D.; López, J. A.; Zharikov, S.; Tovmassian, G.; Borisov, N.; Valyavin, G. E-mail: dgonzalez@astro.unam.mx E-mail: zhar@astro.unam.mx E-mail: borisov@sao.ru

    2014-09-01

    We present the first morpho-kinematical analysis of the planetary nebulae Kn 61 and Pa 5 and explore the nature of their central stars. Our analysis is based on high-resolution and medium-resolution spectroscopic observations, deep narrow-band imaging, and integral photometry. This material allows us to identify the morphological components and study their kinematics. The direct images and spectra indicate an absence of the characteristic [N II] and [S II] emission lines in both nebulae. The nebular spectrum of Kn 61 suggests a hydrogen deficient planetary nebula and the stellar spectrum of the central star reveals a hydrogen-deficient PG 1159-type star. The [O III] position velocity diagram reveals that Kn 61 is a closed, empty, spherical shell with a thin border and a filamentary surface expanding at 67.6 km s{sup –1} and the shell is currently not expanding isotropically. We derived a kinematic age of ∼1.6 × 10{sup 4} yr for an assumed distance of 4 kpc. A photometric period of ∼5.7(±0.4) days has been detected for Kn 61, indicating the presence of a possible binary system at its core. A possible link between filamentary spherical shells and PG 1159-type stars is noted. The morphology of Pa 5 is dominated by an equatorial toroid and faint polar extensions. The equatorial region of this planetary nebula is expanding at 45.2 km s{sup –1}. The stellar spectrum corresponds to a very hot star and is dominated by a steep blue rising continuum and He II, Balmer, and Ca II photospheric lines.

  8. Stability of binaries. Part II: Rubble-pile binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2016-10-01

    We consider the stability of the binary asteroids whose members are granular aggregates held together by self-gravity alone. A binary is said to be stable whenever both its members are orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability analysis of Sharma (Sharma [2015] Icarus, 258, 438-453), that is applicable to binaries with rigid members, to the case of binary systems with rubble members. We employ volume averaging (Sharma et al. [2009] Icarus, 200, 304-322), which was inspired by past work on elastic/fluid, rotating and gravitating ellipsoids. This technique has shown promise when applied to rubble-pile ellipsoids, but requires further work to settle some of its underlying assumptions. The stability test is finally applied to some suspected binary systems, viz., 216 Kleopatra, 624 Hektor and 90 Antiope. We also see that equilibrated binaries that are close to mobilizing their maximum friction can sustain only a narrow range of shapes and, generally, congruent shapes are preferred.

  9. On the origin of binaries with twin components

    NASA Astrophysics Data System (ADS)

    Tokovinin, A. A.

    2000-08-01

    The existence of a statistically significant excess of dwarf binaries with mass ratios from 0.95 to 1, as first noted by Lucy & Ricco (?), is confirmed by modern data. Excess of such binaries, called twins, is found only for periods shorter than 40 days, and in the 2-30 days period range they constitute 10-20% of the total binary population. Twins must have been formed by a special mechanism. It cannot be a mass transfer in contact pre-main-sequence binaries, fission is also unlikely. As shown by Bate (2000), accretion onto a close binary shifts mass ratio towards 1, so twins may originate from binaries that became close while still surrounded by massive envelopes. Many twins are members of higher-multiplicity systems and/or clusters, which probably explains an early formation of a close binary by stellar dynamics.

  10. Terrestrial Planet Formation in Binary Star Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, J. J.; Quintana, E. V.; Adams, F. C.; Chambers, J. E.

    2006-01-01

    Most stars reside in binary/multiple star systems; however, previous models of planet formation have studied growth of bodies orbiting an isolated single star. Disk material has been observed around one or both components of various young close binary star systems. If planets form at the right places within such disks, they can remain dynamically stable for very long times. We have simulated the late stages of growth of terrestrial planets in both circumbinary disks around 'close' binary star systems with stellar separations ($a_B$) in the range 0.05 AU $\\le a_B \\le$ 0.4 AU and binary eccentricities in the range $0 \\le e \\le 0.8$ and circumstellar disks around individual stars with binary separations of tens of AU. The initial disk of planetary embryos is the same as that used for simulating the late stages of terrestrial planet growth within our Solar System and around individual stars in the Alpha Centauri system (Quintana et al. 2002, A.J., 576, 982); giant planets analogous to Jupiter and Saturn are included if their orbits are stable. The planetary systems formed around close binaries with stellar apastron distances less than or equal to 0.2 AU with small stellar eccentricities are very similar to those formed in the Sun-Jupiter-Saturn, whereas planetary systems formed around binaries with larger maximum separations tend to be sparser, with fewer planets, especially interior to 1 AU. Likewise, when the binary periastron exceeds 10 AU, terrestrial planets can form over essentially the entire range of orbits allowed for single stars with Jupiter-like planets, although fewer terrestrial planets tend to form within high eccentricity binary systems. As the binary periastron decreases, the radial extent of the terrestrial planet systems is reduced accordingly. When the periastron is 5 AU, the formation of Earth-like planets near 1 AU is compromised.

  11. Be/X-ray binaries

    NASA Astrophysics Data System (ADS)

    Reig, Pablo

    2011-03-01

    The interest in X/ γ-ray Astronomy has grown enormously in the last decades thanks to the ability to send X-ray space missions above the Earth’s atmosphere. There are more than half a million X-ray sources detected and over a hundred missions (past and currently operational) devoted to the study of cosmic X/ γ rays. With the improved sensibilities of the currently active missions new detections occur almost on a daily basis. Among these, neutron-star X-ray binaries form an important group because they are among the brightest extra-solar objects in the sky and are characterized by dramatic variability in brightness on timescales ranging from milliseconds to months and years. Their main source of power is the gravitational energy released by matter accreted from a companion star and falling onto the neutron star in a relatively close binary system. Neutron-star X-ray binaries divide into high-mass and low-mass systems according to whether the mass of the donor star is above ˜8 or below ˜2 M⊙, respectively. Massive X-ray binaries divide further into supergiant X-ray binaries and Be/X-ray binaries depending on the evolutionary status of the optical companion. Virtually all Be/X-ray binaries show X-ray pulsations. Therefore, these systems can be used as unique natural laboratories to investigate the properties of matter under extreme conditions of gravity and magnetic field. The purpose of this work is to review the observational properties of Be/X-ray binaries. The open questions in Be/X-ray binaries include those related to the Be star companion, that is, the so-called “Be phenomenon”, such as, timescales associated to the formation and dissipation of the equatorial disc, mass-ejection mechanisms, V/ R variability, and rotation rates; those related to the neutron star, such as, mass determination, accretion physics, and spin period evolution; but also, those that result from the interaction of the two constituents, such as, disc truncation and mass

  12. Stability of multiplanet systems in binaries

    NASA Astrophysics Data System (ADS)

    Marzari, F.; Gallina, G.

    2016-10-01

    Context. When exploring the stability of multiplanet systems in binaries, two parameters are normally exploited: the critical semimajor axis ac computed by Holman & Wiegert (1999, AJ, 117, 621) within which planets are stable against the binary perturbations, and the Hill stability limit Δ determining the minimum separation beyond which two planets will avoid mutual close encounters. Both these parameters are derived in different contexts, i.e. Δ is usually adopted for computing the stability limit of two planets around a single star while ac is computed for a single planet in a binary system. Aims: Our aim is to test whether these two parameters can be safely applied in multiplanet systems in binaries or if their predictions fail for particular binary orbital configurations. Methods: We have used the frequency map analysis (FMA) to measure the diffusion of orbits in the phase space as an indicator of chaotic behaviour. Results: First we revisited the reliability of the empirical formula computing ac in the case of single planets in binaries and we find that, in some cases, it underestimates by 10-20% the real outer limit of stability and it does not account for planets trapped in resonance with the companion star well beyond ac. For two-planet systems, the value of Δ is close to that computed for planets around single stars, but the level of chaoticity close to it substantially increases for smaller semimajor axes and higher eccentricities of the binary orbit. In these configurations ac also begins to be unreliable and non-linear secular resonances with the stellar companion lead to chaotic behaviour well within ac, even for single planet systems. For two planet systems, the superposition of mean motion resonances, either mutual or with the binary companion, and non-linear secular resonances may lead to chaotic behaviour in all cases. We have developed a parametric semi-empirical formula determining the minimum value of the binary semimajor axis, for a given

  13. R144: a very massive binary likely ejected from R136 through a binary-binary encounter

    NASA Astrophysics Data System (ADS)

    Oh, Seungkyung; Kroupa, Pavel; Banerjee, Sambaran

    2014-02-01

    R144 is a recently confirmed very massive, spectroscopic binary which appears isolated from the core of the massive young star cluster R136. The dynamical ejection hypothesis as an origin for its location is claimed improbable by Sana et al. due to its binary nature and high mass. We demonstrate here by means of direct N-body calculations that a very massive binary system can be readily dynamically ejected from an R136-like cluster, through a close encounter with a very massive system. One out of four N-body cluster models produces a dynamically ejected very massive binary system with a mass comparable to R144. The system has a system mass of ≈355 M⊙ and is located at 36.8 pc from the centre of its parent cluster, moving away from the cluster with a velocity of 57 km s-1 at 2 Myr as a result of a binary-binary interaction. This implies that R144 could have been ejected from R136 through a strong encounter with another massive binary or single star. In addition, we discuss all massive binaries and single stars which are ejected dynamically from their parent cluster in the N-body models.

  14. Stability of binaries. Part 1: Rigid binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2015-09-01

    We consider the stability of binary asteroids whose members are possibly granular aggregates held together by self-gravity alone. A binary is said to be stable whenever each member is orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability test for rotating granular aggregates introduced by Sharma (Sharma, I. [2012]. J. Fluid Mech., 708, 71-99; Sharma, I. [2013]. Icarus, 223, 367-382; Sharma, I. [2014]. Icarus, 229, 278-294) to the case of binary systems comprised of rubble members. In part I, we specialize to the case of a binary with rigid members subjected to full three-dimensional perturbations. Finally, we employ the stability test to critically appraise shape models of four suspected binary systems, viz., 216 Kleopatra, 25143 Itokawa, 624 Hektor and 90 Antiope.

  15. Hydrodynamic Simulations of Contact Binaries

    NASA Astrophysics Data System (ADS)

    Kadam, Kundan; Clayton, Geoffrey C.; Frank, Juhan; Marcello, Dominic; Motl, Patrick M.; Staff, Jan E.

    2015-01-01

    The motivation for our project is the peculiar case of the 'red nova" V1309 Sco which erupted in September 2008. The progenitor was, in fact, a contact binary system. We are developing a simulation of contact binaries, so that their formation, structural, and merger properties could be studied using hydrodynamics codes. The observed transient event was the disruption of the secondary star by the primary, and their subsequent merger into one star; hence to replicate this behavior, we need a core-envelope structure for both the stars. We achieve this using a combination of Self Consistant Field (SCF) technique and composite polytropes, also known as bipolytropes. So far we have been able to generate close binaries with various mass ratios. Another consequence of using bipolytropes is that according to theoretical calculations, the radius of a star should expand when the core mass fraction exceeds a critical value, resulting in interesting consequences in a binary system. We present some initial results of these simulations.

  16. Close encounters of three black holes

    SciTech Connect

    Campanelli, Manuela; Lousto, Carlos O.; Zlochower, Yosef

    2008-05-15

    We present the first fully relativistic long-term numerical evolutions of three equal-mass black holes in a system consisting of a third black hole in a close orbit about a black-hole binary. These close-three-black-hole systems have very different merger dynamics from black-hole binaries; displaying complex trajectories, a redistribution of energy that can impart substantial kicks to one of the holes, distinctive waveforms, and suppression of the emitted gravitational radiation. In one configuration the binary is quickly disrupted and the individual holes follow complicated trajectories and merge with the third hole in rapid succession, while in another, the binary completes a half-orbit before the initial merger of one of the members with the third black hole, and the resulting two-black-hole system forms a highly elliptical, well separated binary that shows no significant inspiral for (at least) the first t{approx}1000M of evolution.

  17. Binary mask programmable hologram.

    PubMed

    Tsang, P W M; Poon, T-C; Zhou, Changhe; Cheung, K W K

    2012-11-19

    We report, for the first time, the concept and generation of a novel Fresnel hologram called the digital binary mask programmable hologram (BMPH). A BMPH is comprised of a static, high resolution binary grating that is overlaid with a lower resolution binary mask. The reconstructed image of the BMPH can be programmed to approximate a target image (including both intensity and depth information) by configuring the pattern of the binary mask with a simple genetic algorithm (SGA). As the low resolution binary mask can be realized with less stringent display technology, our method enables the development of simple and economical holographic video display.

  18. BPASS predictions for binary black hole mergers

    NASA Astrophysics Data System (ADS)

    Eldridge, J. J.; Stanway, E. R.

    2016-11-01

    Using the Binary Population and Spectral Synthesis code, BPASS, we have calculated the rates, time-scales and mass distributions for binary black hole (BH) mergers as a function of metallicity. We consider these in the context of the recently reported first Laser Interferometer Gravitational-Wave Observatory (LIGO) event detection. We find that the event has a very low probability of arising from a stellar population with initial metallicity mass fraction above Z = 0.010 (Z ≳ 0.5 Z⊙). Binary BH merger events with the reported masses are most likely in populations below 0.008 (Z ≲ 0.4 Z⊙). Events of this kind can occur at all stellar population ages from 3 Myr up to the age of the Universe, but constitute only 0.1-0.4 per cent of binary BH mergers between metallicities of Z = 0.001 and 0.008. However at metallicity Z = 10-4, 26 per cent of binary BH mergers would be expected to have the reported masses. At this metallicity, the progenitor merger times can be close to ≈10 Gyr and rotationally mixed stars evolving through quasi-homogeneous evolution, due to mass transfer in a binary, dominate the rate. The masses inferred for the BHs in the binary progenitor of GW 150914 are amongst the most massive expected at anything but the lowest metallicities in our models. We discuss the implications of our analysis for the electromagnetic follow-up of future LIGO event detections.

  19. Terrestrial Planet Formation in Binary Star Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Quintana, Elisa V.; Chambers, John; Duncan, Martin J.; Adams, Fred

    2003-01-01

    Most stars reside in multiple star systems; however, virtually all models of planetary growth have assumed an isolated single star. Numerical simulations of the collapse of molecular cloud cores to form binary stars suggest that disks will form within such systems. Observations indirectly suggest disk material around one or both components within young binary star systems. If planets form at the right places within such circumstellar disks, they can remain in stable orbits within the binary star systems for eons. We are simulating the late stages of growth of terrestrial planets within binary star systems, using a new, ultrafast, symplectic integrator that we have developed for this purpose. We show that the late stages of terrestrial planet formation can indeed take place in a wide variety of binary systems and we have begun to delineate the range of parameter space for which this statement is true. Results of our initial simulations of planetary growth around each star in the alpha Centauri system and other 'wide' binary systems, as well as around both stars in very close binary systems, will be presented.

  20. Encounters between binaries and neutron stars

    NASA Technical Reports Server (NTRS)

    Davies, M. B.; Benz, W.; Hills, J. G.

    1993-01-01

    We simulated encounters between a neutron star and primordial and tidal-capture binaries. In the case of encounters involving a tidal-capture binary, comprising a white dwarf and a main-sequence star, we find that most exchange encounters will produce a single merged object with the white dwarf and neutron star engulfed in a common envelope of gas donated by the main-sequence primary of the original binary. A small fraction of exchanges induce a merger of the white dwarf and main-sequence star, with this object being unbound to the neutron star, and the two objects having a large relative speed at infinity. For encounters involving a primordial binary, fewer encounters require the inclusion of hydrodynamical effects. Those involving collisions or close encounters tend to produce a binary comprised of the two merged stars (now forming one star) and the third star. The binaries produced typically have large enough separations to prevent the formation of a single merged object until subsequent stellar evolution of one of the components causes it to fill its Roche lobe. Clean exchanges produce binaries with large eccentricities; they are typically sufficiently wide to avoid circularization.

  1. Search for Binary Trojans

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Grundy, W. M.; Ryan, E. L.; Benecchi, S. D.

    2015-11-01

    We have reexamined 41 Trojan asteroids observed with the Hubble Space Telescope (HST) to search for unresolved binaries. We have identified one candidate binary with a separation of 53 milliarcsec, about the width of the diffraction limited point-spread function (PSF). Sub-resolution-element detection of binaries is possible with HST because of the high signal-to-noise ratio of the observations and the stability of the PSF. Identification and confirmation of binary Trojans is important because a Trojan Tour is one of five possible New Frontiers missions. A binary could constitute a potentially high value target because of the opportunity to study two objects and to test models of the primordial nature of binaries. The potential to derive mass-based physical information from the binary orbit could yield more clues to the origin of Trojans.

  2. The formation of eccentric compact binary inspirals and the role of gravitational wave emission in binary-single stellar encounters

    SciTech Connect

    Samsing, Johan; MacLeod, Morgan; Ramirez-Ruiz, Enrico

    2014-03-20

    The inspiral and merger of eccentric binaries leads to gravitational waveforms distinct from those generated by circularly merging binaries. Dynamical environments can assemble binaries with high eccentricity and peak frequencies within the LIGO band. In this paper, we study binary-single stellar scatterings occurring in dense stellar systems as a source of eccentrically inspiraling binaries. Many interactions between compact binaries and single objects are characterized by chaotic resonances in which the binary-single system undergoes many exchanges before reaching a final state. During these chaotic resonances, a pair of objects has a non-negligible probability of experiencing a very close passage. Significant orbital energy and angular momentum are carried away from the system by gravitational wave (GW) radiation in these close passages, and in some cases this implies an inspiral time shorter than the orbital period of the bound third body. We derive the cross section for such dynamical inspiral outcomes through analytical arguments and through numerical scattering experiments including GW losses. We show that the cross section for dynamical inspirals grows with increasing target binary semi-major axis a and that for equal-mass binaries it scales as a {sup 2/7}. Thus, we expect wide target binaries to predominantly contribute to the production of these relativistic outcomes. We estimate that eccentric inspirals account for approximately 1% of dynamically assembled non-eccentric merging binaries. While these events are rare, we show that binary-single scatterings are a more effective formation channel than single-single captures for the production of eccentrically inspiraling binaries, even given modest binary fractions.

  3. PHOEBE: PHysics Of Eclipsing BinariEs

    NASA Astrophysics Data System (ADS)

    Prsa, Andrej; Matijevic, Gal; Latkovic, Olivera; Vilardell, Francesc; Wils, Patrick

    2011-06-01

    PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing binary stars, built on top of the widely used WD program (Wilson & Devinney 1971). This introductory paper overviews most important scientific extensions (incorporating observational spectra of eclipsing binaries into the solution-seeking process, extracting individual temperatures from observed color indices, main-sequence constraining and proper treatment of the reddening), numerical innovations (suggested improvements to WD's Differential Corrections method, the new Nelder & Mead's downhill Simplex method) and technical aspects (back-end scripter structure, graphical user interface). While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to enhance WD by encompassing even more physics and solution reliability.

  4. New algorithms for binary wavefront optimization

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolong; Kner, Peter

    2015-03-01

    Binary amplitude modulation promises to allow rapid focusing through strongly scattering media with a large number of segments due to the faster update rates of digital micromirror devices (DMDs) compared to spatial light modulators (SLMs). While binary amplitude modulation has a lower theoretical enhancement than phase modulation, the faster update rate should more than compensate for the difference - a factor of π2 /2. Here we present two new algorithms, a genetic algorithm and a transmission matrix algorithm, for optimizing the focus with binary amplitude modulation that achieve enhancements close to the theoretical maximum. Genetic algorithms have been shown to work well in noisy environments and we show that the genetic algorithm performs better than a stepwise algorithm. Transmission matrix algorithms allow complete characterization and control of the medium but require phase control either at the input or output. Here we introduce a transmission matrix algorithm that works with only binary amplitude control and intensity measurements. We apply these algorithms to binary amplitude modulation using a Texas Instruments Digital Micromirror Device. Here we report an enhancement of 152 with 1536 segments (9.90%×N) using a genetic algorithm with binary amplitude modulation and an enhancement of 136 with 1536 segments (8.9%×N) using an intensity-only transmission matrix algorithm.

  5. Long-Term Stability of Planets in Binary Systems

    NASA Technical Reports Server (NTRS)

    Holman, Matthew J.; Wiegert, Paul A.

    1999-01-01

    A simple question of celestial mechanics is investigated: in what regions of phase space near a binary system can planets persist for long times? The planets are taken to be test particles moving in the field of an eccentric binary system. A range of values of the binary eccentricity and mass ratio is studied, and both the case of planets orbiting close to one of the stars, and that of planets outside the binary orbiting the systems center of mass, are examined. From the results, empirical expressions are developed for both (1) the largest orbit around each of the stars and (2) the smallest orbit around the binary system as a whole, in which test particles survive the length of the integration (10A4 binary periods). The empirical expressions developed, which are roughly linear in both the mass ratio mu and the binary eccentricity e, are determined for the range 0.0=e=0.7-0.8 and 0.1=mu=0.9 in both regions and can be used to guide searches for planets in binary systems. After considering the case of a single low-mass planet in binary systems, the stability of a mutually interacting system of planets orbiting one star of a binary system is examined, though in less detail.

  6. TWIN BINARIES: STUDIES OF STABILITY, MASS TRANSFER, AND COALESCENCE

    SciTech Connect

    Lombardi, J. C.; Holtzman, W.; Gearity, K.; Dooley, K. L.; Kalogera, V.; Rasio, F. A.

    2011-08-20

    Motivated by suggestions that binaries with almost equal-mass components ('twins') play an important role in the formation of double neutron stars and may be rather abundant among binaries, we study the stability of synchronized close and contact binaries with identical components in circular orbits. In particular, we investigate the dependency of the innermost stable circular orbit on the core mass, and we study the coalescence of the binary that occurs at smaller separations. For twin binaries composed of convective main-sequence stars, subgiants, or giants with low-mass cores (M{sub c} {approx}< 0.15M, where M is the mass of a component), a secular instability is reached during the contact phase, accompanied by a dynamical mass transfer instability at the same or at a slightly smaller orbital separation. Binaries that come inside this instability limit transfer mass gradually from one component to the other and then coalesce quickly as mass is lost through the outer Lagrangian points. For twin giant binaries with moderate to massive cores (M{sub c} {approx}> 0.15M), we find that stable contact configurations exist at all separations down to the Roche limit, when mass shedding through the outer Lagrangian points triggers a coalescence of the envelopes and leaves the cores orbiting in a central tight binary. In addition to the formation of binary neutron stars, we also discuss the implications of our results for the production of planetary nebulae with double degenerate central binaries.

  7. Massive binaries in the vicinity of Sgr A*

    SciTech Connect

    Pfuhl, O.; Gillessen, S.; Genzel, R.; Eisenhauer, F.; Fritz, T. K.; Ott, T.; Alexander, T.; Martins, F.

    2014-02-20

    A long-term spectroscopic and photometric survey of the most luminous and massive stars in the vicinity of the supermassive black hole Sgr A* revealed two new binaries: a long-period Ofpe/WN9 binary, IRS 16NE, with a modest eccentricity of 0.3 and a period of 224 days, and an eclipsing Wolf-Rayet binary with a period of 2.3 days. Together with the already identified binary IRS 16SW, there are now three confirmed OB/WR binaries in the inner 0.2 pc of the Galactic center. Using radial velocity change upper limits, we were able to constrain the spectroscopic binary fraction in the Galactic center to F{sub SB}=0.30{sub −0.21}{sup +0.34} at a confidence level of 95%, a massive binary fraction close to that observed in dense clusters. The fraction of eclipsing binaries with photometric amplitudes Δm > 0.4 is F{sub EB}{sup GC}=3%±2%, which is consistent with local OB star clusters (F {sub EB} = 1%). Overall, the Galactic center binary fraction seems to be similar to the binary fraction in comparable young clusters.

  8. Massive Stars in Interactive Binaries

    NASA Astrophysics Data System (ADS)

    St.-Louis, Nicole; Moffat, Anthony F. J.

    Massive stars start their lives above a mass of ~8 time solar, finally exploding after a few million years as core-collapse or pair-production supernovae. Above ~15 solar masses, they also spend most of their lives driving especially strong, hot winds due to their extreme luminosities. All of these aspects dominate the ecology of the Universe, from element enrichment to stirring up and ionizing the interstellar medium. But when they occur in close pairs or groups separated by less than a parsec, the interaction of massive stars can lead to various exotic phenomena which would not be seen if there were no binaries. These depend on the actual separation, and going from wie to close including colliding winds (with non-thermal radio emission and Wolf-Rayet dust spirals), cluster dynamics, X-ray binaries, Roche-lobe overflow (with inverse mass-ratios and rapid spin up), collisions, merging, rejuventation and massive blue stragglers, black-hole formation, runaways and gamma-ray bursts. Also, one wonders whether the fact that a massive star is in a binary affects its parameters compared to its isolated equivalent. These proceedings deal with all of these phenomena, plus binary statistics and determination of general physical properties of massive stars, that would not be possible with their single cousins. The 77 articles published in these proceedings, all based on oral talks, vary from broad revies to the lates developments in the field. About a third of the time was spent in open discussion of all participants, both for ~5 minutes after each talk and 8 half-hour long general dialogues, all audio-recorded, transcribed and only moderately edited to yield a real flavour of the meeting. The candid information in these discussions is sometimes more revealing than the article(s) that preceded them and also provide entertaining reading. The book is suitable for researchers and graduate students interested in stellar astrophysics and in various physical processes involved when

  9. [Closing diastemas].

    PubMed

    Vieira, L C; Pereira, J C; Coradazzi, J L; Francischone, C E

    1990-01-01

    The authors describe a clinical case of closing upper central incisives diastema, reconstructiva of a conoid upper lateral and the rechaping of an upper canine to a lateral incisive. The material used was composite resin.

  10. Binaries and triples among asteroid pairs

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Scheirich, Peter; Kušnirák, Peter; Hornoch, Kamil; Galád, Adrián

    2015-08-01

    Despite major achievements obtained during the past two decades, our knowledge of the population and properties of small binary and multiple asteroid systems is still far from advanced. There is a numerous indirect evidence for that most small asteroid systems were formed by rotational fission of cohesionless parent asteroids that were spun up to the critical frequency presumably by YORP, but details of the process are lacking. Furthermore, as we proceed with observations of more and more binary and paired asteroids, we reveal new facts that substantially refine and sometimes change our understanding of the asteroid systems. One significant new finding we have recently obtained is that primaries of many asteroid pairs are actually binary or triple systems. The first such case found is (3749) Balam (Vokrouhlický, ApJL 706, L37, 2009). We have found 9 more binary systems among asteroid pairs within our ongoing NEOSource photometric project since October 2012. They are (6369) 1983 UC, (8306) Shoko, (9783) Tensho-kan, (10123) Fideoja, (21436) Chaoyichi, (43008) 1999 UD31, (44620) 1999 RS43, (46829) 1998 OS14 and (80218) 1999 VO123. We will review their characteristics. These paired binaries as we call them are mostly similar to binaries in the general ("background") population (of unpaired asteroids), but there are a few trends. The paired binaries tend to have larger secondaries with D_2/D_1 = 0.3 to 0.5 and they also tend to be wider systems with 8 of the 10 having orbital periods between 30 and 81 hours, than average among binaries in the general population. There may be also a larger fraction of triples; (3749) Balam is a confirmed triple, having a larger close and a smaller distant satellite, and (8306) Shoko and (10123) Fideoja are suspect triples as they show additional rotational lightcurve components with periods of 61 and 38.8 h that differ from the orbital period of 36.2 and 56.5 h, respectively. The unbound secondaries tend to be of the same size or

  11. Binaries in globular clusters

    NASA Technical Reports Server (NTRS)

    Hut, Piet; Mcmillan, Steve; Goodman, Jeremy; Mateo, Mario; Phinney, E. S.; Pryor, Carlton; Richer, Harvey B.; Verbunt, Frank; Weinberg, Martin

    1992-01-01

    Recent observations have shown that globular clusters contain a substantial number of binaries most of which are believed to be primordial. We discuss different successful optical search techniques, based on radial-velocity variables, photometric variables, and the positions of stars in the color-magnitude diagram. In addition, we review searches in other wavelengths, which have turned up low-mass X-ray binaries and more recently a variety of radio pulsars. On the theoretical side, we give an overview of the different physical mechanisms through which individual binaries evolve. We discuss the various simulation techniques which recently have been employed to study the effects of a primordial binary population, and the fascinating interplay between stellar evolution and stellar dynamics which drives globular-cluster evolution.

  12. Sometimes binary is better

    NASA Astrophysics Data System (ADS)

    Sprows, David

    2015-04-01

    This note uses material involving perfect numbers and Zeno's paradoxes to show that although most students prefer to use base 10 when working with mathematical concepts there are times when the binary system is best.

  13. Double Degenerate Binary Systems

    SciTech Connect

    Yakut, K.

    2011-09-21

    In this study, angular momentum loss via gravitational radiation in double degenerate binary (DDB)systems (NS + NS, NS + WD, WD + WD, and AM CVn) is studied. Energy loss by gravitational waves has been estimated for each type of systems.

  14. X-ray binaries

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

  15. Binary-Symmetry Detection

    NASA Technical Reports Server (NTRS)

    Lopez, Hiram

    1987-01-01

    Transmission errors for zeros and ones tabulated separately. Binary-symmetry detector employs psuedo-random data pattern used as test message coming through channel. Message then modulo-2 added to locally generated and synchronized version of test data pattern in same manner found in manufactured test sets of today. Binary symmetrical channel shows nearly 50-percent ones to 50-percent zeroes correspondence. Degree of asymmetry represents imbalances due to either modulation, transmission, or demodulation processes of system when perturbed by noise.

  16. Scattering from binary optics

    NASA Technical Reports Server (NTRS)

    Ricks, Douglas W.

    1993-01-01

    There are a number of sources of scattering in binary optics: etch depth errors, line edge errors, quantization errors, roughness, and the binary approximation to the ideal surface. These sources of scattering can be systematic (deterministic) or random. In this paper, scattering formulas for both systematic and random errors are derived using Fourier optics. These formulas can be used to explain the results of scattering measurements and computer simulations.

  17. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  18. Orbits of 6 Binaries

    NASA Astrophysics Data System (ADS)

    Olevic, D.; Cvetkovic, Z.

    In this paper the orbits of binaries WDS 10093+2020 = A 2145, WDS 21074-0814 = BU 368 AB and WDS 22288-0001 = STF 2909 AB are recalculated because of significant deviations of more recent observations from the ephemerides. For binaries WDS 22384-0754 = A 2695, WDS 23474-7118 = FIN 375 Aa and WDS 23578+2508 = McA 76 the orbital elements are calculated for the first time.

  19. Testing the Binary Trigger Hypothesis in FUors

    NASA Astrophysics Data System (ADS)

    Green, Joel D.; Kraus, Adam L.; Rizzuto, Aaron C.; Ireland, Michael J.; Dupuy, Trent J.; Mann, Andrew W.; Kuruwita, Rajika

    2016-10-01

    We present observations of three FU Orionis objects (hereafter, FUors) with nonredundant aperture-mask interferometry at 1.59 μm and 2.12 μm that probe for binary companions on the scale of the protoplanetary disk that feeds their accretion outbursts. We do not identify any companions to V1515 Cyg or HBC 722, but we do resolve a close binary companion to V1057 Cyg that is at the diffraction limit (ρ =58.3+/- 1.4 mas or 30 ± 5 au) and currently much fainter than the outbursting star ({{Δ }}K\\prime =3.34+/- 0.10 mag). Given the flux excess of the outbursting star, we estimate that the mass of the companion (M∼ 0.25{M}ȯ ) is similar to or slightly below that of the FUor itself, and therefore it resembles a typical T Tauri binary system. Our observations only achieve contrast limits of {{Δ }}K\\prime ∼ 4 mag, and hence we are only sensitive to companions that were near or above the pre-outburst luminosity of the FUors. It remains plausible that FUor outbursts could be tied to the presence of a close binary companion. However, we argue from the system geometry and mass reservoir considerations that these outbursts are not directly tied to the orbital period (i.e., occurring at periastron passage), but instead must only occur infrequently.

  20. The structure and evolution of interacting binary galaxies

    NASA Astrophysics Data System (ADS)

    Borne, K. D.

    1983-08-01

    A numerical code was constructed for the study of the evolution of interacting binary galaxies. This "multiple three-body" algorithm (MTBA) essentially involves N concurrent three-body integrations. MTBA incorporates a violent relaxation phase that allows the particles to redistribute themselves in the gravitational field of the perturber prior to the full binary orbital evolution calculation. This redistribution is important for systems with an initially strong tidal potential; their predicted merger times are 50-100% larger than previously estimated. Merger times are tabulated both for circular and for elliptical orbits. Typical close binary galaxies will merge in about twice their initial binary oribtal periods. A specific interacting binary simulation is described in detail in the first paper. Many of the results reported here are consistent with those obtained from the larger, more expensive N-body simulations. MTBA is altered so that each "galaxy" is represented by a configuration of test particles.

  1. BINARY CANDIDATES IN THE JOVIAN TROJAN AND HILDA POPULATIONS FROM NEOWISE LIGHT CURVES

    SciTech Connect

    Sonnett, S.; Mainzer, A.; Masiero, J.; Bauer, J.; Grav, T.

    2015-02-01

    Determining the binary fraction for a population of asteroids, particularly as a function of separation between the two components, helps describe the dynamical environment at the time the binaries formed, which in turn offers constraints on the dynamical evolution of the solar system. We searched the NEOWISE archival data set for close and contact binary Trojans and Hildas via their diagnostically large light curve amplitudes. We present 48 out of 554 Hilda and 34 out of 953 Trojan binary candidates in need of follow-up to confirm their large light curve amplitudes and subsequently constrain the binary orbit and component sizes. From these candidates, we calculate a preliminary estimate of the binary fraction without confirmation or debiasing of 14%-23% for Trojans larger than ∼12 km and 30%-51% for Hildas larger than ∼4 km. Once the binary candidates have been confirmed, it should be possible to infer the underlying, debiased binary fraction through estimation of survey biases.

  2. Solar System binaries

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    The discovery of binaries in each of the major populations of minor bodies in the solar system is propelling a rapid growth of heretofore unattainable physical information. The availability of mass and density constraints for minor bodies opens the door to studies of internal structure, comparisons with meteorite samples, and correlations between bulk-physical and surface-spectral properties. The number of known binaries is now more than 70 and is growing rapidly. A smaller number have had the extensive followup observations needed to derive mass and albedo information, but this list is growing as well. It will soon be the case that we will know more about the physical parameters of objects in the Kuiper Belt than has been known about asteroids in the Main Belt for the last 200 years. Another important aspect of binaries is understanding the mechanisms that lead to their formation and survival. The relative sizes and separations of binaries in the different minor body populations point to more than one mechanism for forming bound pairs. Collisions appear to play a major role in the Main Belt. Rotational and/or tidal fission may be important in the Near Earth population. For the Kuiper Belt, capture in multi-body interactions may be the preferred formation mechanism. However, all of these conclusions remain tentative and limited by observational and theoretical incompleteness. Observational techniques for identifying binaries are equally varied. High angular resolution observations from space and from the ground are critical for detection of the relatively distant binaries in the Main Belt and the Kuiper Belt. Radar has been the most productive method for detection of Near Earth binaries. Lightcurve analysis is an independent technique that is capable of exploring phase space inaccessible to direct observations. Finally, spacecraft flybys have played a crucial paradigm-changing role with discoveries that unlocked this now-burgeoning field.

  3. Shape Shifting Satellites in Binary Near-Earth Asteroids: Do Meteoroid Impacts Play a Role in BYORP Orbital Evolution?

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    2012-01-01

    Less than catastrophic meteoroid impacts over 10(exp 5) years may change the shape of small rubble-pile satellites in binary NEAs, lengthening the average BYORP (binary Yarkovsky-Radzievskii-Paddack) rate of orbital evolution. An estimate of shape-shifting meteoroid fluxes give numbers close enough to causing random walks in the semimajor axis of binary systems to warrant further investigation

  4. Thermal Radio Emission from Radiative Shocks in Colliding Wind Binaries

    NASA Astrophysics Data System (ADS)

    Montes, G.; González, R. F.; Cantó, J.; Pérez-Torres, M. A.; Alberdi, A.

    2011-10-01

    We present a semi-analytic model for computing the thermal radio continuum emission from radiative shocks within colliding wind binaries. Assuming a thin shell approximation, we calculate the contribution of the wind collision region (WCR) to the total thermal emission for close binaries. We investigate the effect of the binary separation on the total spectrum. In addition, we point out the relevance of taking into account this contribution for the correct interpretation of the observations, and the accuracy of parameters derived from them.

  5. EXTRASOLAR BINARY PLANETS. II. DETECTABILITY BY TRANSIT OBSERVATIONS

    SciTech Connect

    Lewis, K. M.; Ida, S.; Ochiai, H.; Nagasawa, M.

    2015-05-20

    We discuss the detectability of gravitationally bound pairs of gas-giant planets (which we call “binary planets”) in extrasolar planetary systems that are formed through orbital instability followed by planet–planet dynamical tides during their close encounters, based on the results of N-body simulations by Ochiai et al. (Paper I). Paper I showed that the formation probability of a binary is as much as ∼10% for three giant planet systems that undergo orbital instability, and after post-capture long-term tidal evolution, the typical binary separation is three to five times the sum of the physical radii of the planets. The binary planets are stable during the main-sequence lifetime of solar-type stars, if the stellarcentric semimajor axis of the binary is larger than 0.3 AU. We show that detecting modulations of transit light curves is the most promising observational method to detect binary planets. Since the likely binary separations are comparable to the stellar diameter, the shape of the transit light curve is different from transit to transit, depending on the phase of the binary’s orbit. The transit durations and depth for binary planet transits are generally longer and deeper than those for the single planet case. We point out that binary planets could exist among the known inflated gas-giant planets or objects classified as false positive detections at orbital radii ≳0.3 AU, propose a binary planet explanation for the CoRoT candidate SRc01 E2 1066, and show that binary planets are likely to be present in, and could be detected using, Kepler-quality data.

  6. Cosmological Impact of Population III Binaries

    NASA Astrophysics Data System (ADS)

    Chen, Ke-Jung; Bromm, Volker; Heger, Alexander; Jeon, Myoungwon; Woosley, Stan

    2015-03-01

    We present the results of the stellar feedback from Population III (Pop III) binaries by employing improved, more realistic Pop III evolutionary stellar models. To facilitate a meaningful comparison, we consider a fixed mass of 60 {{M}⊙ } incorporated in Pop III stars, either contained in a single star, or split up in binary stars of 30 {{M}⊙ } each or an asymmetric case of one 45 and one 15 {{M}⊙ } star. Whereas the sizes of the resulting H ii regions are comparable across all cases, the He iii regions around binary stars are significantly smaller than that of the single star. Consequently, the He+ 1640 \\overset{\\circ}A recombination line is expected to become much weaker. Supernova (SN) feedback exhibits great variety due to the uncertainty in possible explosion pathways. If at least one of the component stars dies as a hypernova about 10 times more energetic than conventional core-collapse SNe, the gas inside the host minihalo is effectively blown out, chemically enriching the intergalactic medium (IGM) to an average metallicity of {{10}-4}-{{10}-3} {{Z}⊙ }, out to ˜ 2 kpc. The single star, however, is more likely to collapse into a black hole, accompanied by at most very weak explosions. The effectiveness of early chemical enrichment would thus be significantly reduced, in contrast to the lower mass binary stars, where at least one component is likely to contribute to heavy element production and dispersal. Important new feedback physics is also introduced if close binaries can form high-mass X-ray binaries, leading to the pre-heating and -ionization of the IGM beyond the extent of the stellar H ii regions.

  7. Kepler's Cool Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Swift, Jonathan; Muirhead, P. S.; Johnson, J. A.; Gonzales, A.; Shporer, A.; Plavchan, P.; Lockwood, A.; Morton, T.

    2014-01-01

    Some of the most exciting exoplanet results to date have come from the smallest and coolest sample of stars in the Kepler field—the M dwarfs. These cool stars represent the largest stellar population in the Galaxy which in turn harbors one of the largest known exoplanet populations. However, an accurate understanding of their physical properties currently eludes us. Detached, M dwarf eclipsing binary systems provide an accurate and precise, model-independent means of measuring the fundamental properties of low-mass stars shedding light on the rich physics embodied by this spectral class and refining our knowledge of their exoplanets. We have undertaken an observational campaign to obtain masses, radii, and effective temperatures of the Kepler eclipsing binaries having an M dwarf primary with periods between 1 and 60 days. These data will allow detailed comparisons between stellar properties, binary period, rotation, metallicity and activity levels.

  8. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, Gerald P.; Zhao, Jianmin; Feng, Zhen

    1996-01-01

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered.

  9. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, G.P.; Zhao, J.; Feng, Z.

    1996-12-03

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered. 3 figs.

  10. Two new extremely hot pulsating white dwarfs

    NASA Technical Reports Server (NTRS)

    Bond, H. E.; Grauer, A. D.; Green, R. F.; Liebert, J. W.

    1984-01-01

    High speed photometry of the extremely hot, nearly degenerate stars PG 1707 + 427 and PG 2131 + 066 reveals that they are low-amplitude pulsating variables. Power spectral analysis shows both to be multiperiodic, with dominant periods of 7.5 and 6.4-6.9 minutes, respectively. Together with the known pulsators PG 1159 - 035 and the central star of the planetary nebula Kohoutek 1-16, these objects define a new pulsational instability strip at the hot edge of the H-R diagram. The variations of these objects closely resemble those of the much cooler pulsating ZZ Ceti DA white dwarfs; both groups are probably nonradial g-mode pulsators. Evolutionary contraction of the PG 1159 - 035 variables may lead to period changes that would be detectable in as little as 1 year. The optical and IUE spectra of the PG 1159 - 035 variables are characterized by absorption lines of C IV and other CNO ions, indicating radiative levitation of species heavier than helium. He II is also present in the spectra, but the hydrogen Balmer lines are absent. Effective temperatures near 100,000 K are required, and the He II 4686 A profiles indicate log g greater than 6. These helium-rich pulsators form the hottest known subgroup of the DO white dwarfs.

  11. Period Variations in the Close Binary BM UMa

    NASA Astrophysics Data System (ADS)

    Virnina, Natalia A.; Panko, Elena; Sergienko, O. G.; Murnikov, Boris A.; Gubin, E. G.; Klabukova, A. V.; Movchan, A. I.

    2010-12-01

    We present the results of analysing of the light curve and O-C variations in the eclipsing system BM UMa, based on V-band observations which cover the period from JD 2454933 to 2454961 using two robotic remotely-controlled telescopes of Tzec Maun Observatory (USA) along with observations made with the RK-600 telescope of Odessa Astronomical Observatory. The full light curve displays a total primary eclipse with a duration 0.06 of the period, or 24 minutes, and a partial secondary eclipse, with both maxima of equal magnitude. For our obesrvations, we determined the statistically optimal values of the initial epoch of T0 = 2454944.2814 ± 0.0001 and orbital period of P = 0.d271226± 0.000002. The depths of primary and secondary minima are nearly equal, 0.m838 ± 0.006 and 0.m748 ± 0.006, respectively. The physical parameters of the system were calculated using the Wilson-Devinney code, appended with the Monte Carlo search algorithm. The result establishes BM UMa as a contact system (fillout factor 10.7%) with parameters: mass ratio 0.538 ± 0.001, inclination 86.°815 ± 0.005, and temperatures of components 4700 ± 20 K and 4510 ± 10 K. The more massive component is larger and cooler. The 72 archival and 11 newly-obtained times of light minimum cover the interval 1961-2010 and allowed us to exclude possible systematic period variations in BM UMa and to determine an initial epoch of HJD 2447927.382 and orbital period of P = 0.d2712209± 0.0000006.

  12. Ultra-stripped Type Ic Supernovae from Close Binary Evolution

    NASA Astrophysics Data System (ADS)

    Tauris, T. M.; Langer, N.; Moriya, T. J.; Podsiadlowski, Ph.; Yoon, S.-C.; Blinnikov, S. I.

    2013-12-01

    Recent discoveries of weak and fast optical transients raise the question of their origin. We investigate the minimum ejecta mass associated with core-collapse supernovae (SNe) of Type Ic. We show that mass transfer from a helium star to a compact companion can produce an ultra-stripped core which undergoes iron core collapse and leads to an extremely fast and faint SN Ic. In this Letter, a detailed example is presented in which the pre-SN stellar mass is barely above the Chandrasekhar limit, resulting in the ejection of only ~0.05-0.20 M ⊙ of material and the formation of a low-mass neutron star (NS). We compute synthetic light curves of this case and demonstrate that SN 2005ek could be explained by our model. We estimate that the fraction of such ultra-stripped to all SNe could be as high as 10-3-10-2. Finally, we argue that the second explosion in some double NS systems (for example, the double pulsar PSR J0737-3039B) was likely associated with an ultra-stripped SN Ic.

  13. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1996-01-01

    We present preliminary results of our implementation of a novel electrophoresis separation technique: Binary Oscillatory Cross flow Electrophoresis (BOCE). The technique utilizes the interaction of two driving forces, an oscillatory electric field and an oscillatory shear flow, to create an active binary filter for the separation of charged species. Analytical and numerical studies have indicated that this technique is capable of separating proteins with electrophoretic mobilities differing by less than 10%. With an experimental device containing a separation chamber 20 cm long, 5 cm wide, and 1 mm thick, an order of magnitude increase in throughput over commercially available electrophoresis devices is theoretically possible.

  14. Identification list of binaries

    NASA Astrophysics Data System (ADS)

    Malkov,, O.; Karchevsky,, A.; Kaygorodov, P.; Kovaleva, D.

    The Identification List of Binaries (ILB) is a star catalogue constructed to facilitate cross-referencing between different catalogues of binary stars. As of 2015, it comprises designations for approximately 120,000 double/multiple systems. ILB contains star coordinates and cross-references to the Bayer/Flemsteed, DM (BD/CD/CPD), HD, HIP, ADS, WDS, CCDM, TDSC, GCVS, SBC9, IGR (and some other X-ray catalogues), PSR designations, as well as identifications in the recently developed BSDB system. ILB eventually became a part of the BDB stellar database.

  15. Binary coding for hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Chang, Chein-I.; Chang, Chein-Chi; Lin, Chinsu

    2004-10-01

    Binary coding is one of simplest ways to characterize spectral features. One commonly used method is a binary coding-based image software system, called Spectral Analysis Manager (SPAM) for remotely sensed imagery developed by Mazer et al. For a given spectral signature, the SPAM calculates its spectral mean and inter-band spectral difference and uses them as thresholds to generate a binary code word for this particular spectral signature. Such coding scheme is generally effective and also very simple to implement. This paper revisits the SPAM and further develops three new SPAM-based binary coding methods, called equal probability partition (EPP) binary coding, halfway partition (HP) binary coding and median partition (MP) binary coding. These three binary coding methods along with the SPAM well be evaluated for spectral discrimination and identification. In doing so, a new criterion, called a posteriori discrimination probability (APDP) is also introduced for performance measure.

  16. N-Bit Binary Resistor

    NASA Technical Reports Server (NTRS)

    Tcheng, Ping

    1989-01-01

    Binary resistors in series tailored to precise value of resistance. Desired value of resistance obtained by cutting appropriate traces across resistors. Multibit, binary-based, adjustable resistor with high resolution used in many applications where precise resistance required.

  17. Acceleration by pulsar winds in binary systems

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.; Gaisser, T. K.

    1990-01-01

    In the absence of accretion torques, a pulsar in a binary system will spin down due to electromagnetic dipole radiation and the spin-down power will drive a wind of relativistic electron-positron pairs. Winds from pulsars with short periods will prevent any subsequent accretion but may be confined by the companion star atmosphere, wind, or magnetosphere to form a standing shock. The authors investigate the possibility of particle acceleration at such a pulsar wind shock and the production of very high energy (VHE) and ultra high energy (UHE) gamma rays from interactions of accelerated protons in the companion star's wind or atmosphere. They find that in close binaries containing active pulsars, protons will be shock accelerated to a maximum energy dependent on the pulsar spin-down luminosity. If a significant fraction of the spin-down power goes into particle acceleration, these systems should be sources of VHE and possibly UHE gamma rays. The authors discuss the application of the pulsar wind model to binary sources such as Cygnus X-3, as well as the possibility of observing VHE gamma-rays from known binary radio pulsar systems.

  18. Photometric constraints on binary asteroid dynamics

    NASA Astrophysics Data System (ADS)

    Scheirich, Peter

    2015-08-01

    To date, about 50 binary NEAs, 20 Mars-crossing and 80 small MB asteroids are known. We observe also a population of about 200 unbound asteroid systems (asteroid pairs). I will review the photometric observational data we have for the best observed cases and compare them with theories of binary and paired asteroids evolution.The observed characteristics of asteroid systems suggest their formation by rotational fission of parent rubble-pile asteroids after being spun up by the YORP effect. The angular momentum content of binary asteroids is close to critical. The orientations of satellite orbits of observed binary systems are non-random; the orbital poles concentrate near the obliquities of 0 and 180 degrees, i.e., near the YORP asymptotic states.Recently, a significant excess of retrograde satellite orbits was detected, which is not yet explained characteristic.An evolution of binary system depend heavily on the BYORP effect. If BYORP is contractive, the primary and secondary could end in a tidal-BYORP equilibrium. Observations of mutual events between binary components in at least four apparitions are needed for BYORP to be revealed by detecting a quadratic drift in mean anomaly of the satellite. I will show the observational evidence of single-synchronous binary asteroid with tidally locked satellite (175706 1996 FG3), i.e, with the quadratic drift equal to zero, and binary asteroid with contracting orbit (88710 2001 SL9), with positive value of the quadratic drift (the solution for the quadratic drift is ambiguous so far, with possible values of 5 and 8 deg/yr2).The spin configuration of the satellite play a crucial role in the evolution of the system under the influence of the BYORP effect. I will show that the rotational lightcurves of the satellites show that most of them have small libration amplitudes (up to 20 deg.), with a few interesting exceptions.Acknowledgements: This work has been supported by the Grant Agency of the Czech Republic, Grant P209

  19. Binary stars - Formation by fragmentation

    NASA Technical Reports Server (NTRS)

    Boss, Alan P.

    1988-01-01

    Theories of binary star formation by capture, separate nuclei, fission and fragmentation are compared, assessing the success of theoretical attempts to explain the observed properties of main-sequence binary stars. The theory of formation by fragmentation is examined, discussing the prospects for checking the theory against observations of binary premain-sequence stars. It is concluded that formation by fragmentation is successful at explaining many of the key properties of main-sequence binary stars.

  20. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  1. THE ROLE OF KOZAI CYCLES IN NEAR-EARTH BINARY ASTEROIDS

    SciTech Connect

    Fang, Julia; Margot, Jean-Luc

    2012-03-15

    We investigate the Kozai mechanism in the context of near-Earth binaries and the Sun. The Kozai effect can lead to changes in eccentricity and inclination of the binary orbit, but it can be weakened or completely suppressed by other sources of pericenter precession, such as the oblateness of the primary body. Through numerical integrations including primary oblateness and three bodies (the two binary components and the Sun), we show that Kozai cycles cannot occur for the closely separated near-Earth binaries in our sample. We demonstrate that this is due to pericenter precession around the oblate primary, even for very small oblateness values. Since the majority of observed near-Earth binaries are not well separated, we predict that Kozai cycles do not play an important role in the orbital evolution of most near-Earth binaries. For a hypothetical wide binary modeled after 1998 ST27, the separation is large at 16 primary radii and so the orbital effects of primary oblateness are lessened. For this wide binary, we illustrate the possible excursions in eccentricity and inclination due to Kozai cycles as well as depict stable orientations for the binary's orbital plane. Unstable orientations lead to collisions between binary components, and we suggest that the Kozai effect acting in wide binaries may be a route to the formation of near-Earth contact binaries.

  2. SECULAR EVOLUTION OF COMPACT BINARIES NEAR MASSIVE BLACK HOLES: GRAVITATIONAL WAVE SOURCES AND OTHER EXOTICA

    SciTech Connect

    Antonini, Fabio; Perets, Hagai B.

    2012-09-20

    The environment near supermassive black holes (SMBHs) in galactic nuclei contains a large number of stars and compact objects. A fraction of these are likely to be members of binaries. Here we discuss the binary population of stellar black holes and neutron stars near SMBHs and focus on the secular evolution of such binaries, due to the perturbation by the SMBH. Binaries with highly inclined orbits with respect to their orbit around the SMBH are strongly affected by secular Kozai processes, which periodically change their eccentricities and inclinations (Kozai cycles). During periapsis approach, at the highest eccentricities during the Kozai cycles, gravitational wave (GW) emission becomes highly efficient. Some binaries in this environment can inspiral and coalesce at timescales much shorter than a Hubble time and much shorter than similar binaries that do not reside near an SMBH. The close environment of SMBHs could therefore serve as a catalyst for the inspiral and coalescence of binaries and strongly affect their orbital properties. Such compact binaries would be detectable as GW sources by the next generation of GW detectors (e.g., advanced-LIGO). Our analysis shows that {approx}0.5% of such nuclear merging binaries will enter the LIGO observational window while on orbits that are still very eccentric (e {approx}> 0.5). The efficient GW analysis for such systems would therefore require the use of eccentric templates. We also find that binaries very close to the SMBH could evolve through a complex dynamical (non-secular) evolution, leading to emission of several GW pulses during only a few years (though these are likely to be rare). Finally, we note that the formation of close stellar binaries, X-ray binaries, and their merger products could be induced by similar secular processes, combined with tidal friction rather than GW emission as in the case of compact object binaries.

  3. Analytical solutions for elastic binary nanotubes of arbitrary chirality

    NASA Astrophysics Data System (ADS)

    Jiang, Lai; Guo, Wanlin

    2016-09-01

    Analytical solutions for the elastic properties of a variety of binary nanotubes with arbitrary chirality are obtained through the study of systematic molecular mechanics. This molecular mechanics model is first extended to chiral binary nanotubes by introducing an additional out-of-plane inversion term into the so-called stick-spiral model, which results from the polar bonds and the buckling of binary graphitic crystals. The closed-form expressions for the longitudinal and circumferential Young's modulus and Poisson's ratio of chiral binary nanotubes are derived as functions of the tube diameter. The obtained inversion force constants are negative for all types of binary nanotubes, and the predicted tube stiffness is lower than that by the former stick-spiral model without consideration of the inversion term, reflecting the softening effect of the buckling on the elastic properties of binary nanotubes. The obtained properties are shown to be comparable to available density functional theory calculated results and to be chirality and size sensitive. The developed model and explicit solutions provide a systematic understanding of the mechanical performance of binary nanotubes consisting of III-V and II-VI group elements.

  4. Photometric Study of Near Contact Binaries

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Qian, S.

    2009-08-01

    Near Contact Binary (NCB) is a kind of close binary in which both components fill or nearly fill their critical Roche Lobes. They are not in contact like W UMa systems, and show EB-type light variations. These characters make the NCB an interesting object. They are important observational targets which may be lying in key evolutionary states. According to the geometric definition of this subclass, NCBs actually comprise semi-detached with primary filling (SD1) or secondary filling (SD2), marginal-contact (C), and marginal-detached (D) systems. We have observed a group of NCBs (e.g. BL and, GW Tau, AS Ser, UU Lyn, RU UMi, GSC3658-0076 etc. ) and constructed an evolutionary sequence of case A mass transfer in observation. Finally, the available orbital period variations and absolute parameters of NCBs are collected and the preliminary statistical results are presented.

  5. BROWN DWARF BINARIES FROM DISINTEGRATING TRIPLE SYSTEMS

    SciTech Connect

    Reipurth, Bo; Mikkola, Seppo E-mail: Seppo.Mikkola@utu.fi

    2015-04-15

    Binaries in which both components are brown dwarfs (BDs) are being discovered at an increasing rate, and their properties may hold clues to their origin. We have carried out 200,000 N-body simulations of three identical stellar embryos with masses drawn from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions within the cloud core, while accreting using Bondi–Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. In order to illustrate 200,000 end-states of such dynamical evolution with accretion, we introduce the “triple diagnostic diagram,” which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations, and statistical properties are derived. The separation distribution function is in good correspondence with observations, showing a steep rise at close separations, peaking around 13 AU and declining more gently, reaching zero at separations greater than 200 AU. Unresolved BD triple systems may appear as wider BD binaries. Mass ratios are strongly peaked toward unity, as observed, but this is partially due to the initial assumptions. Eccentricities gradually increase toward higher values, due to the lack of viscous interactions in the simulations, which would both shrink the orbits and decrease their eccentricities. Most newborn triple systems are unstable and while there are 9209 ejected BD binaries at 1 Myr, corresponding to about 4% of the 200,000 simulations, this number has grown to

  6. Brown Dwarf Binaries from Disintegrating Triple Systems

    NASA Astrophysics Data System (ADS)

    Reipurth, Bo; Mikkola, Seppo

    2015-04-01

    Binaries in which both components are brown dwarfs (BDs) are being discovered at an increasing rate, and their properties may hold clues to their origin. We have carried out 200,000 N-body simulations of three identical stellar embryos with masses drawn from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions within the cloud core, while accreting using Bondi-Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. In order to illustrate 200,000 end-states of such dynamical evolution with accretion, we introduce the “triple diagnostic diagram,” which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations, and statistical properties are derived. The separation distribution function is in good correspondence with observations, showing a steep rise at close separations, peaking around 13 AU and declining more gently, reaching zero at separations greater than 200 AU. Unresolved BD triple systems may appear as wider BD binaries. Mass ratios are strongly peaked toward unity, as observed, but this is partially due to the initial assumptions. Eccentricities gradually increase toward higher values, due to the lack of viscous interactions in the simulations, which would both shrink the orbits and decrease their eccentricities. Most newborn triple systems are unstable and while there are 9209 ejected BD binaries at 1 Myr, corresponding to about 4% of the 200,000 simulations, this number has grown to

  7. THE DISPERSAL OF PROTOPLANETARY DISKS AROUND BINARY STARS

    SciTech Connect

    Alexander, Richard

    2012-10-01

    I present models of disk evolution around young binary stars. I show that the primary factor in determining circumbinary disk lifetimes is the rate of disk photoevaporation. I also find that photoevaporative clearing leaves a signature on the distribution of circumbinary disk lifetimes, with a sharp increase in disk lifetimes for binary separations a {approx}< 0.3-1 AU. Observations of young binary stars can therefore be used to test models of disk evolution, and I show that current data set a strong upper limit to the rate of on-going photoevaporation (<10{sup -9} M{sub Sun} yr{sup -1}). Finally I discuss the implications of these results for planet formation and suggest that circumbinary planets around close (a {approx}< 1 AU) binaries should be relatively common.

  8. STAR HOPPERS: PLANET INSTABILITY AND CAPTURE IN EVOLVING BINARY SYSTEMS

    SciTech Connect

    Kratter, Kaitlin M.; Perets, Hagai B.

    2012-07-01

    Many planets are observed in stellar binary systems, and their frequency may be comparable to that of planetary systems around single stars. Binary stellar evolution in such systems influences the dynamical evolution of the resident planets. Here, we study the evolution of a single planet orbiting one star in an evolving binary system. We find that stellar evolution can trigger dynamical instabilities that drive planets into chaotic orbits. This instability leads to planet-star collisions, exchange of the planet between the binary stars ('star hoppers'), and ejection of the planet from the system. The means by which planets can be recaptured is similar to the pull-down capture mechanism for irregular solar system satellites. Because planets often suffer close encounters with the primary on the asymptotic giant branch, captures during a collision with the stellar envelope are also possible for more massive planets. Such capture could populate the habitable zone around white dwarfs.

  9. Massive Black Hole Binary Evolution

    NASA Astrophysics Data System (ADS)

    Merritt, David; Milosavljević, Milos

    2005-11-01

    Coalescence of binary supermassive black holes (SBHs) would constitute the strongest sources of gravitational waves to be observed by LISA. While the formation of binary SBHs during galaxy mergers is almost inevitable, coalescence requires that the separation between binary components first drop by a few orders of magnitude, due presumably to interaction of the binary with stars and gas in a galactic nucleus. This article reviews the observational evidence for binary SBHs and discusses how they would evolve. No completely convincing case of a bound, binary SBH has yet been found, although a handful of systems (e.g. interacting galaxies; remnants of galaxy mergers) are now believed to contain two SBHs at projected separations of <~ 1kpc. N-body studies of binary evolution in gas-free galaxies have reached large enough particle numbers to reproduce the slow, "diffusive" refilling of the binary's loss cone that is believed to characterize binary evolution in real galactic nuclei. While some of the results of these simulations - e.g. the binary hardening rate and eccentricity evolution - are strongly N-dependent, others - e.g. the "damage" inflicted by the binary on the nucleus - are not. Luminous early-type galaxies often exhibit depleted cores with masses of ~ 1-2 times the mass of their nuclear SBHs, consistent with the predictions of the binary model. Studies of the interaction of massive binaries with gas are still in their infancy, although much progress is expected in the near future. Binary coalescence has a large influence on the spins of SBHs, even for mass ratios as extreme as 10:1, and evidence of spin-flips may have been observed.

  10. Binary Love relations

    NASA Astrophysics Data System (ADS)

    Yagi, Kent; Yunes, Nicolás

    2016-07-01

    When in a tight binary, the mutual tidal deformations of neutron stars get imprinted onto observables, encoding information about their internal structure at supranuclear densities and gravity in the extreme-gravity regime. Gravitational wave (GW) observations of their late binary inspiral may serve as a tool to extract the individual tidal deformabilities, but this is made difficult by degeneracies between them in the GW model. We here resolve this problem by discovering approximately equation-of-state (EoS)-insensitive relations between dimensionless combinations of the individual tidal deformabilities. We show that these relations break degeneracies in the GW model, allowing for the accurate extraction of both deformabilities. Such measurements can be used to better differentiate between EoS models, and improve tests of general relativity and cosmology.

  11. Young and Waltzing Binary Stars

    NASA Astrophysics Data System (ADS)

    2001-10-01

    they can also be used to check ("calibrate") other, indirect methods to derive stellar parameters. It is on this background that the first discovery of an eclipsing binary system with two young, solar-like stars is of great interest. The Orion Binary Young stars are not so easy to find. One way is to look for their high-energy emission from a hot corona, created by their enhanced magnetic activity. The object RXJ 0529.4+0041 was first discovered in this way by the X-ray satellite ROSAT. Subsequent optical spectroscopy showed this object to be a young, low-mass spectroscopic binary system. And when a team of astronomers [1] used a 91-cm telescope at the Serra La Nave observing station on the slope of the Etna volcano (Sicily) to monitor the light curve, they also discovered that this system undergoes eclipses. All data confirm that RXJ 0529.4+0041 is located in the Orion Nebula at a distance of about 1500 light-years. This is one of the nearest star-forming regions and almost all stars in this area are quite young. Spectroscopic observations soon confirmed that the binary system was no exception. In particular, fairly strong absorption lines of the fragile element Lithium [4] were detected in both of the binary stars. As Lithium is known to be rapidly destroyed in stars, the finding of a relatively high content of this element implies that the stars must indeed be young. They were probably formed no more than 10 million years ago, i.e., in astronomical terms, they are "infant" stars . High-resolution spectroscopic observations, mostly with the CORALIE spectrometer on the Swiss 1.2-m Leonard Euler telescope at the ESO La Silla Observatory , were used to determine the radial velocities of the stars. From these, a first determination of the orbital and stellar parameters was possible. The orbital period turned out to be short. The two stars swing around each other in just 3 days. This also means they must be very close to each other (but still entirely detached from each

  12. Parametric binary dissection

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.; Crockett, Thomas W.; Nicol, David M.

    1993-01-01

    Binary dissection is widely used to partition non-uniform domains over parallel computers. This algorithm does not consider the perimeter, surface area, or aspect ratio of the regions being generated and can yield decompositions that have poor communication to computation ratio. Parametric Binary Dissection (PBD) is a new algorithm in which each cut is chosen to minimize load + lambda x(shape). In a 2 (or 3) dimensional problem, load is the amount of computation to be performed in a subregion and shape could refer to the perimeter (respectively surface) of that subregion. Shape is a measure of communication overhead and the parameter permits us to trade off load imbalance against communication overhead. When A is zero, the algorithm reduces to plain binary dissection. This algorithm can be used to partition graphs embedded in 2 or 3-d. Load is the number of nodes in a subregion, shape the number of edges that leave that subregion, and lambda the ratio of time to communicate over an edge to the time to compute at a node. An algorithm is presented that finds the depth d parametric dissection of an embedded graph with n vertices and e edges in O(max(n log n, de)) time, which is an improvement over the O(dn log n) time of plain binary dissection. Parallel versions of this algorithm are also presented; the best of these requires O((n/p) log(sup 3)p) time on a p processor hypercube, assuming graphs of bounded degree. How PBD is applied to 3-d unstructured meshes and yields partitions that are better than those obtained by plain dissection is described. Its application to the color image quantization problem is also discussed, in which samples in a high-resolution color space are mapped onto a lower resolution space in a way that minimizes the color error.

  13. Binary Optics Toolkit

    1996-04-02

    This software is a set of tools for the design and analysis of binary optics. It consists of a series of stand-alone programs written in C and some scripts written in an application-specific language interpreted by a CAD program called DW2000. This software can be used to optimize the design and placement of a complex lens array from input to output and produce contours, mask designs, and data exported for diffractive optic analysis.

  14. Separated Fringe Packet Binaries

    NASA Astrophysics Data System (ADS)

    Bagnuolo, W. G.; Taylor, S. F.; McAlister, H. A.; ten Brummelaar, T.; Sturmann, L.; Sturmann, J.; Turner, N. H.; Berger, D.; Ridgway, S. T.; CenterHigh Angular Resolution Astronomy (CHARA)

    2004-12-01

    Individually resolved packets are produced by scans from the CHARA Interferometer Array for binary stars with separations from 10 to 100 milli-arcsec (mas) in the K' band. We have used this data for astrometry of the binary with the goal of improving the visual orbits for these systems. About 12 data sets of 400 scans each can be collected for a star within an hour. The intrinsic accuracy with simple linear/quadratic fits to the time-separation curve yields accuracies of 0.15 mas. But, for systems with separations less than 80 mas, the measured separation is modulated periodically by the secondary star's packet riding over the sidelobes of the primary which provides a phase reference. This "sidelobe verniering" can improve the precision to better than 50 micro-arcsec. These techniques, represents 1-2 orders of magnitude improvement in astrometic accuracy over speckle interferometry techniques. Visual orbits can then be refined via a maximum liklihood technique, which leads to revisions in the stellar masses. We present the results for several binaries that have been observed at the CHARA Array, starting in 2001.

  15. Evolutionary models of binaries

    NASA Astrophysics Data System (ADS)

    van Rensbergen, Walter; Mennekens, Nicki; de Greve, Jean-Pierre; Jansen, Kim; de Loore, Bert

    2011-07-01

    We have put on CDS a catalog containing 561 evolutionary models of binaries: J/A+A/487/1129 (Van Rensbergen+, 2008). The catalog covers a grid of binaries with a B-type primary at birth, different values for the initial mass ratio and a wide range of initial orbital periods. The evolution was calculated with the Brussels code in which we introduced the spinning up and the creation of a hot spot on the gainer or its accretion disk, caused by impacting mass coming from the donor. When the kinetic energy of fast rotation added to the radiative energy of the hot spot exceeds the binding energy, a fraction of the transferred matter leaves the system: the evolution is liberal during a short lasting era of rapid mass transfer. The spin-up of the gainer was modulated using both strong and weak tides. The catalog shows the results for both types. For comparison, we included the evolutionary tracks calculated with the conservative assumption. Binaries with an initial primary below 6 Msolar show hardly any mass loss from the system and thus evolve conservatively. Above this limit differences between liberal and conservative evolution grow with increasing initial mass of the primary star.

  16. A precontact binary and a shallow contact binary are in the same field

    NASA Astrophysics Data System (ADS)

    Liu, Liang; Qian, Shengbang; He, Jiajia; Liao, Wenping; Liu, Nianping

    2016-06-01

    The period changes of two close binaries, V1107 Cas and AX Cas, which are in the same field, were investigated. Their periods both show a long-term decrease. After further analysis, we found that the periods have their respective cyclic oscillations (T3 = 6.74 ± 0.24 yr for V1107 Cas and T3 = 13.8 ± 0.3 yr for AX Cas), which are possibly caused by a third body due to the light-time effect. We also obtained the complete VRcIc light curves for V1107 Cas and analyzed them with the 2010 version of the Wilson-Devinney code. The photometric results reveal that V1107 Cas is a W-type shallow contact (15.2%±1.8%) binary, with a mass-ratio of 1.797 ± 0.006. The period variation and photometric solution suggest that V1107 Cas is a newly formed contact binary system. Moreover, we estimated the fundamental parameters for V1107 Cas. They are: M1 = 0.39 ± 0.01 M⊙, M2 = 0.70 ± 0.03 M⊙, R1 = 0.52 ± 0.10 R⊙, R2 = 0.68 ± 0.12 R⊙, L1 = 0.178 ± 0.108 L⊙, and L2 = 0.196 ± 0.116 L⊙. Then, based on the coplane assumption, we deduced the masses of possible third bodies to be M3 = 0.091 ± 0.019 M⊙ for V1107 Cas and M3 = 0.325 ± 0.029 M⊙ for AX Cas. Finally, we inferred the evolutional stage of AX Cas, and believe that it is a precontact binary. Thus, the precontact binary AX Cas and the shallow contact binary V1107 Cas have adjoining evolutional stages.

  17. Binary-Signal Recovery

    NASA Technical Reports Server (NTRS)

    Griebeler, Elmer L.

    2011-01-01

    Binary communication through long cables, opto-isolators, isolating transformers, or repeaters can become distorted in characteristic ways. The usual solution is to slow the communication rate, change to a different method, or improve the communication media. It would help if the characteristic distortions could be accommodated at the receiving end to ease the communication problem. The distortions come from loss of the high-frequency content, which adds slopes to the transitions from ones to zeroes and zeroes to ones. This weakens the definition of the ones and zeroes in the time domain. The other major distortion is the reduction of low frequency, which causes the voltage that defines the ones or zeroes to drift out of recognizable range. This development describes a method for recovering a binary data stream from a signal that has been subjected to a loss of both higher-frequency content and low-frequency content that is essential to define the difference between ones and zeroes. The method makes use of the frequency structure of the waveform created by the data stream, and then enhances the characteristics related to the data to reconstruct the binary switching pattern. A major issue is simplicity. The approach taken here is to take the first derivative of the signal and then feed it to a hysteresis switch. This is equivalent in practice to using a non-resonant band pass filter feeding a Schmitt trigger. Obviously, the derivative signal needs to be offset to halfway between the thresholds of the hysteresis switch, and amplified so that the derivatives reliably exceed the thresholds. A transition from a zero to a one is the most substantial, fastest plus movement of voltage, and therefore will create the largest plus first derivative pulse. Since the quiet state of the derivative is sitting between the hysteresis thresholds, the plus pulse exceeds the plus threshold, switching the hysteresis switch plus, which re-establishes the data zero to one transition

  18. Merging Galaxies Create a Binary Quasar

    NASA Astrophysics Data System (ADS)

    2010-02-01

    Observatory in California indicated that the object was likely a binary quasar in the midst of a galaxy merger. Carnegie's Mulchaey then used the 6.5 meter Baade-Magellan telescope at the Las Campanas observatory in Chile to obtain deeper images and more detailed spectroscopy of the merging galaxies. "Just because you see two galaxies that are close to each other in the sky doesn't mean they are merging," says Mulchaey. "But from the Magellan images we can actually see tidal tails, one from each galaxy, which suggests that the galaxies are in fact interacting and are in the process of merging." Thomas Cox, now a fellow at the Carnegie Observatories, corroborated this conclusion using computer simulations of the merging galaxies. When Cox's model galaxies merged, they showed features remarkably similar to what Mulchaey observed in the Magellan images. "The model verifies the merger origin for this binary quasar system," he says. "It also hints that this kind of galaxy interaction is a key component of the growth of black holes and production of quasars throughout our universe." * The authors of the paper published in the Astrophysical Journal are Paul J. Green of the Harvard-Smithsonian Center for Astrophysics, Adam D. Myers of the University of Illinois at Urbana-Champaign, Wayne A. Barkhouse of the University of North Dakota, John S. Mulchaey of the Observatories of the Carnegie Institution for Science, Vardha N. Bennert of the Department of Physics, University of California, Santa Barbara, Thomas J. Cox of the Observatories of the Carnegie Institution for Science, Thomas L. Aldcroft of the Harvard-Smithsonian Center for Astrophysics, and Joan M. Wrobel of National Radio Astronomy Observatory, Socorro, NM. More information, including images and other multimedia, can be found at: http://chandra.harvard.edu and http://chandra.nasa.gov

  19. Analysis of the Interferometric Binary Finsen 332

    NASA Astrophysics Data System (ADS)

    Mason, Brian D.; Hartkopf, W. I.; McAlister, H. A.

    2010-01-01

    Two of the most challenging objects for optical interferometry in the middle of the last century were the close components (FIN 332) of the wide visual binary STF2375 (= WDS 18455+0530 = HIP 92027 = ADS 11640). Each component of the wide pair was found to have subcomponents of approximately the same magnitude, position angle and separation and, hence, were designated by the tongue in cheek monikers "Tweedledum and Tweedledee" by the great visual interferometrist William S. Finsen in 1953. They were later included in a list of "Double Stars that Vex the Observer" by W.H. van den Bos. While speckle interferometry has reaped a rich harvest investigating the close inteferometric binaries of Finsen, the "Tweedles" have continued to both fascinate and exasperate due to both the great similarity of the close pairs as well as the inherent 180 degree ambiguity associated with interferometry. Detailed analysis of all published observations of the system have revealed several errors which are here corrected, allowing for determination of these orbital elements which resolve the quadrant ambiguity. A unique software filter was developed which allowed subarrays from archival ICCD speckle data from 1982 to be re-reduced. Those data, combined with new and unpublished observations obtained in 2001-9 from NOAO 4m telescopes, the Mt. Wilson 100in telescope and the NOFS 61in telescope as well as high quality unresolved measures all allow for the correct orbits to be determined. Co-planarity of the multiple system is also investigated.

  20. Binary optics: Trends and limitations

    NASA Technical Reports Server (NTRS)

    Farn, Michael W.; Veldkamp, Wilfrid B.

    1993-01-01

    We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

  1. Binary optics: Trends and limitations

    NASA Astrophysics Data System (ADS)

    Farn, Michael W.; Veldkamp, Wilfrid B.

    1993-08-01

    We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

  2. Spectroscopic observations of V443 Herculis - A symbiotic binary with a low mass white dwarf

    NASA Technical Reports Server (NTRS)

    Dobrzycka, Danuta; Kenyon, Scott J.; Mikolajewska, Joanna

    1993-01-01

    We present an analysis of new and existing photometric and spectroscopic observations of the symbiotic binary V443 Herculis. This binary system consists of a normal M5 giant and a hot compact star. These two objects have comparable luminosities: about 1500 solar for the M5 giant and about 1000 solar for the compact star. We identify three nebular regions in this binary: a small, highly ionized volume surrounding the hot component, a modestly ionized shell close to the red giant photosphere, and a less dense region of intermediate ionization encompassing both binary components. The system parameters for V443 Her suggest the hot component currently declines from a symbiotic nova eruption.

  3. Binary Stars in Globular Clusters

    NASA Astrophysics Data System (ADS)

    Mateo, M.; Murdin, P.

    2000-11-01

    Globular clusters have long been known to be among the richest stellar groupings within our Galaxy, but for many years they were believed to be largely devoid of the most minimal stellar group: binary stars (see BINARY STARS: OVERVIEW). For many years, the only evidence that any binaries existed in these clusters came from the presence of BLUE STRAGGLERS—stars that appear to be significantly you...

  4. Observations of mass accretion in binary stars

    NASA Technical Reports Server (NTRS)

    Polidan, R. S.; Peters, G. J.

    1982-01-01

    Results from high resolution observations of eight close binary stars (TX UMa, U CrB, CX Dra, TT Hya, AU Mon, KX And, HR 2142, and phi Per) are presented. Variable absorption lines, indicative of mass flow, are observed in all systems expect phi Per. Emission lines are seen in KX And and phi Per. Variable high ionization features (NV, SiIV, and CIV) are seen in TX UMa, UCrB, CX Dra, and AU Mon. The observations are modeled using the calculations of Lubow and Shu.

  5. Binary Cepheids From High-Angular Resolution

    NASA Astrophysics Data System (ADS)

    Gallenne, A.; Mérand, A.; Kervella, P.

    2015-12-01

    Optical interferometry is the only technique giving access to milli-arcsecond (mas) spatial resolution. This is a powerful and unique tool to detect the close orbiting companions of Cepheids, and offers an unique opportunity to make progress in resolving the Cepheid mass discrepancy. Our goal in studying binary Cepheids is to measure the astrometric position of the high-contrast companion, and then combine them with spectroscopic measurements to derive the orbital elements, distances, and dynamical masses. In the course of this program, we developed a new tool, CANDID, to search for high-contrast companions and set detection limits from interferometric observations

  6. Accretion Disks in Massive Binary Systems

    NASA Astrophysics Data System (ADS)

    Djurašević, G. R.; Vince, I.; Atanacković, O.

    2010-12-01

    The results of our investigations of some massive close binaries (CB) (RY Sct, V448 Cyg, UU Cas and V455 Cyg), based on the photometric and spectroscopic observations indicate the existance of the accretion disk around the more massive component, located deep inside the Roche lobe. The light curve shapes of some of this systems are similar to the ones of the overcontact systems like W UMa, but the nature of these massive CBs is completely different. Here we present the models of these systems and their basic elements.

  7. Composition formulas of binary eutectics

    PubMed Central

    Ma, Y. P.; Dong, D. D.; Dong, C.; Luo, L. J.; Wang, Q.; Qiang, J. B.; Wang, Y. M.

    2015-01-01

    The present paper addresses the long-standing composition puzzle of eutectic points by introducing a new structural tool for the description of short-range-order structural unit, the cluster-plus-glue-atom model. In this model, any structure is dissociated into a 1st-neighbor cluster and a few glue atoms between the clusters, expressed by a cluster formula [cluster]gluex. This model is applied here to establish the structural model for eutectic liquids, assuming that a eutectic liquid consist of two subunits issued from the relevant eutectic phases, each being expressed by the cluster formula for ideal metallic glasses, i.e., [cluster](glue atom)1 or 3. A structural unit is then composed of two clusters from the relevant eutectic phases plus 2, 4, or 6 glue atoms. Such a dual cluster formulism is well validated in all boron-containing (except those located by the extreme phase diagram ends) and in some commonly-encountered binary eutectics, within accuracies below 1 at.%. The dual cluster formulas vary extensively and are rarely identical even for eutectics of close compositions. They are generally formed with two distinctly different cluster types, with special cluster matching rules such as cuboctahedron plus capped trigonal prism and rhombidodecahedron plus octahedral antiprism. PMID:26658618

  8. Low autocorrelation binary sequences

    NASA Astrophysics Data System (ADS)

    Packebusch, Tom; Mertens, Stephan

    2016-04-01

    Binary sequences with minimal autocorrelations have applications in communication engineering, mathematics and computer science. In statistical physics they appear as groundstates of the Bernasconi model. Finding these sequences is a notoriously hard problem, that so far can be solved only by exhaustive search. We review recent algorithms and present a new algorithm that finds optimal sequences of length N in time O(N {1.73}N). We computed all optimal sequences for N≤slant 66 and all optimal skewsymmetric sequences for N≤slant 119.

  9. BINARY STORAGE ELEMENT

    DOEpatents

    Chu, J.C.

    1958-06-10

    A binary storage device is described comprising a toggle provided with associsted improved driver circuits adapted to produce reliable action of the toggle during clearing of the toggle to one of its two states. or transferring information into and out of the toggle. The invention resides in the development of a self-regulating driver circuit to minimize the fluctuation of the driving voltages for the toggle. The disclosed driver circuit produces two pulses in response to an input pulse: a first or ''clear'' pulse beginning nt substantially the same time but endlrg slightly sooner than the second or ''transfer'' output pulse.

  10. The ζ Aurigae Binaries

    NASA Astrophysics Data System (ADS)

    Griffin, R. Elizabeth; Ake, Thomas B.

    This opening chapter provides a brief historical overview of the ζ Aur stars, with a focus on what K.O. Wright, his predecessors and colleagues at the Dominion Astrophysical Observatory, and his contemporaries further afield, achieved during the era of pre-electronic data. It places the topic within the framework of modern observing, data management and computing, outlines the principal features of the chromospheric-eclipse phenomena which single out the ζ Aur binaries for special study, and describes the considerable potential which this remarkable yet very select group of stars offers for increasing our understanding of stellar physics.

  11. Binary porous convection

    NASA Astrophysics Data System (ADS)

    Carey, Michael Richard

    Binary porous convection falls into the larger category of pattern formation---a symmetry breaking instability which creates a spatially periodic structure within a homogeneous system. The experiments and model presented in this dissertation indicate that an essential piece of physics is missing from the standard Darcian picture used to describe pattern formation in a porous medium convection system. Present theory predicts a bifurcation to an oscillatory state at onset for a binary mixture in a porous media over a wide range of experimental parameters (Brand and Steinberg, Physics Letters 93A 333 (1983)). This theory is inadequate in explaining the predominant large amplitude, backward, stationary overturning convection state observed in our experiments after transients have decayed. Convection experiments were visualized with magnetic resonance imaging and performed with a foam medium in slot and cylindrical geometries as well as a rectangular, packed bead system with water-ethanol mixtures. We explore the possibility that the difference between theory and experiment is due to enhanced solutal mixing not included in previous theories. The enhanced mixing of the fluid produces an effective diffusion coefficient that largely suppresses gradients in the concentration field, resulting in single-fluid like behavior. We model the experimental system with a Lorenz truncation of the binary Darcy equations with enhanced mixing. This model predicts results qualitatively similar to experiments: a forward bifurcation to small amplitude oscillations with a secondary backward bifurcation to large amplitude stationary convection. We have also developed an experimental nuclear magnetic resonance technique that measures the effective diffusion coefficient, D = D(v), as a function of velocity, v, for the individual species of the binary mixture simultaneously. However, the mixing effect measured in plug flow experiments is roughly two to three orders of magnitude too small to have

  12. Apparent horizons in binary black hole spacetimes

    NASA Astrophysics Data System (ADS)

    Shoemaker, Deirdre Marie

    Over the last decade, advances in computing technology and numerical techniques have lead to the possible theoretical prediction of astrophysically relevant waveforms in numerical simulations. With the building of gravitational wave detectors such as the Laser Interferometric Gravitational-Wave Observatory, we stand at the epoch that will usher in the first experimental study of strong field general relativity. One candidate source for ground based detection of gravitational waveforms, the orbit and merger of two black holes, is of great interest to the relativity community. The binary black hole problem is the two-body problem in general relativity. It is a stringent dynamical test of the theory. The problem involves the evolution of the Einstein equation, a complex system of non-linear, dynamic, elliptic-hyperbolic equations intractable in closed form. Numerical relativists are now developing the technology to evolve the Einstein equation using numerical simulations. The generation of these numerical I codes is a ``theoretical laboratory'' designed to study strong field phenomena in general relativity. This dissertation reports the successful development and application of the first multiple apparent horizon tracker applied to the generic binary black hole problem. I have developed a method that combines a level set of surfaces with a curvature flow method. This method, which I call the level flow method, locates the surfaces of any apparent horizons in the spacetime. The surface location then is used to remove the singularities from the computational domain in the evolution code. I establish the following set of criteria desired in an apparent horizon tracker: (1)The robustness of the tracker due to its lack of dependence on small changes to the initial guess; (2)The generality of the tracker in its applicability to generic spacetimes including multiple back hole spacetimes; and (3)The efficiency of the tracker algorithm in CPU time. I demonstrate the apparent

  13. Some (Apparently) Very Wide Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Warner, Brian D.; Harris, Alan W.; Stephens, Robert D.

    2016-10-01

    We present lightcurves for some of the approximately one dozen asteroids that appear to be very widely-separated binaries. Jacobsen et al. (2014, ApJ 780) attribute their formation to a somewhat complex series of events involving BYORP.The lightcurves consist of two components: Period 1 (P1) is very long, P1 = 50-600 h, with amplitudes of A1 = 0.23-1.0 mag. The second period and amplitudes are similar to the primaries of close binary systems, i.e., P2 = 2.2-3.6 h, A2 ~ 0.10 mag. Two candidates have secondary periods in the range of 5-7 hours. The most exceptional example is (19204) Joshuatree, which has values of P1 = 480 h, A1 = 0.25 mag and P2 = 21.25 h, A2 = 0.08 mag. Based on Jacobson et al. (2014, ApJ 780) and Pravec et al. (2016, Icarus 267), we suggest that P1 represents the primary (larger) body of the system and P2 represents the spin rate of the satellite.Supporting this supposition is that the large amplitude (A1) must be from the larger body, otherwise the dilution of amplitude would require the smaller body to be unreasonably elongate. The limiting size ratio for binaries is around 0.6 (see Pravec et al. 2010, Nature 466, Fig. 1), or a magnitude difference of about 1.0. For a secondary 1.0 mag fainter than the primary to produce a combined lightcurve amplitude of ~0.4 mag would require that the secondary undiluted amplitude to be several magnitudes (near-infinite elongation) and also a near equatorial aspect. This is not likely.Given the lack of mutual events, these can be considered to be only possible binaries. Since the orbital period is probably very long, it seems extremely unlikely that mutual events will ever be seen.The changing landscape of binary asteroid discoveries and theories calls for something beyond descriptive terms such as "suspicious", "possible", "likely", and "confirmed" in order to allow more accurate statistical studies. To this end, we are introducing a new "B" rating in the asteroid lightcurve database (Warner et al., 2009

  14. Misaligned protoplanetary disks in a young binary star system.

    PubMed

    Jensen, Eric L N; Akeson, Rachel

    2014-07-31

    Many extrasolar planets follow orbits that differ from the nearly coplanar and circular orbits found in our Solar System; their orbits may be eccentric or inclined with respect to the host star's equator, and the population of giant planets orbiting close to their host stars suggests appreciable orbital migration. There is at present no consensus on what produces such orbits. Theoretical explanations often invoke interactions with a binary companion star in an orbit that is inclined relative to the planet's orbital plane. Such mechanisms require significant mutual inclinations between the planetary and binary star orbital planes. The protoplanetary disks in a few young binaries are misaligned, but often the measurements of these misalignments are sensitive only to a small portion of the inner disk, and the three-dimensional misalignment of the bulk of the planet-forming disk mass has hitherto not been determined. Here we report that the protoplanetary disks in the young binary system HK Tauri are misaligned by 60 to 68 degrees, such that one or both of the disks are significantly inclined to the binary orbital plane. Our results demonstrate that the necessary conditions exist for misalignment-driven mechanisms to modify planetary orbits, and that these conditions are present at the time of planet formation, apparently because of the binary formation process. PMID:25079553

  15. Misaligned protoplanetary disks in a young binary star system.

    PubMed

    Jensen, Eric L N; Akeson, Rachel

    2014-07-31

    Many extrasolar planets follow orbits that differ from the nearly coplanar and circular orbits found in our Solar System; their orbits may be eccentric or inclined with respect to the host star's equator, and the population of giant planets orbiting close to their host stars suggests appreciable orbital migration. There is at present no consensus on what produces such orbits. Theoretical explanations often invoke interactions with a binary companion star in an orbit that is inclined relative to the planet's orbital plane. Such mechanisms require significant mutual inclinations between the planetary and binary star orbital planes. The protoplanetary disks in a few young binaries are misaligned, but often the measurements of these misalignments are sensitive only to a small portion of the inner disk, and the three-dimensional misalignment of the bulk of the planet-forming disk mass has hitherto not been determined. Here we report that the protoplanetary disks in the young binary system HK Tauri are misaligned by 60 to 68 degrees, such that one or both of the disks are significantly inclined to the binary orbital plane. Our results demonstrate that the necessary conditions exist for misalignment-driven mechanisms to modify planetary orbits, and that these conditions are present at the time of planet formation, apparently because of the binary formation process.

  16. The binary Kuiper-belt object 1998 WW31.

    PubMed

    Veillet, Christian; Parker, Joel Wm; Griffin, Ian; Marsden, Brian; Doressoundiram, Alain; Buie, Marc; Tholen, David J; Connelley, Michael; Holman, Matthew J

    2002-04-18

    The recent discovery of a binary asteroid during a spacecraft fly-by generated keen interest, because the orbital parameters of binaries can provide measures of the masses, and mutual eclipses could allow us to determine individual sizes and bulk densities. Several binary near-Earth, main-belt and Trojan asteroids have subsequently been discovered. The Kuiper belt-the region of space extending from Neptune (at 30 astronomical units) to well over 100 AU and believed to be the source of new short-period comets-has become a fascinating new window onto the formation of our Solar System since the first member object, not counting Pluto, was discovered in 1992 (ref. 13). Here we report that the Kuiper-belt object 1998 WW31 is binary with a highly eccentric orbit (eccentricity e approximately 0.8) and a long period (about 570 days), very different from the Pluto/Charon system, which was hitherto the only previously known binary in the Kuiper belt. Assuming a density in the range of 1 to 2 g cm-3, the albedo of the binary components is between 0.05 and 0.08, close to the value of 0.04 generally assumed for Kuiper-belt objects. PMID:11961547

  17. Influence of binary fraction on the fragmentation of young massive clusters—a Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Tanuka; Sinha, Abisa; Chattopadhyay, Asis Kumar

    2016-04-01

    A stochastic model has been developed to study the hierarchical fragmentation process of young massive clusters in external galaxies considering close binary components along with individual ones. Stellar masses for individual ones have been generated from truncated Pareto distribution and stellar masses for close binary components have been generated from a truncated Bi-variate Gumbel Exponential distribution. The above distribution is identified by fitting the observed bi-variate distribution of masses of eclipsing binary stars computed from the light curves catalogued in the package Binary Maker 3.0. The resulting mass spectra computed at different projected distances, show signature of mass segregation. Degree of mass segregation becomes reduced due to the inclusion of binary fraction. This might be due to the reduction of massive stars and inclusion of less massive stars rather than inclusion of single massive stars and the effect of line of sight length projected to an observer.

  18. Modeling Binary Neutron Stars

    NASA Astrophysics Data System (ADS)

    Park, Conner; Read, Jocelyn; Flynn, Eric; Lockett-Ruiz, Veronica

    2016-03-01

    Gravitational waves, predicted by Einstein's Theory of Relativity, are a new frontier in astronomical observation we can use to observe phenomena in the universe. Laser Interferometer Gravitational wave Observatory (LIGO) is currently searching for gravitational wave signals, and requires accurate predictions in order to best extract astronomical signals from all other sources of fluctuations. The focus of my research is in increasing the accuracy of Post-Newtonian models of binary neutron star coalescence to match the computationally expensive Numerical models. Numerical simulations can take months to compute a couple of milliseconds of signal whereas the Post-Newtonian can generate similar signals in seconds. However the Post-Newtonian model is an approximation, e.g. the Taylor T4 Post-Newtonian model assumes that the two bodies in the binary neutron star system are point charges. To increase the effectiveness of the approximation, I added in tidal effects, resonance frequencies, and a windowing function. Using these observed effects from simulations significantly increases the Post-Newtonian model's similarity to the Numerical signal.

  19. Planetary Formation and Dynamics in Binary Systems

    NASA Astrophysics Data System (ADS)

    Xie, J. W.

    2013-01-01

    explanation for the turnover point in the size distribution of the present-day asteroid belt. For the specific case of close binaries such as Alpha Centauri, the snowball growth mode provides a safe way for the bodies to grow through the problematic range with a size of 1˜50 km. In chapter 6, we investigate the intermediate stages of the planet formation in highly inclined cases. We find that the gas drag plays a crucial role in the evolution of the planetesimals' semi-major axis, and the results can be generally divided into two categories, i.e., the Kozai-on regime and the Kozai-off regime. For both regimes, a robust outcome over a wide range of parameters is that, the planetesimals migrate/jump inwards and pile up, leading to a severely truncated and dense planetesimal disk around the primary. In this compact and dense disk, the collision rates are high but the relative velocities are low, providing conditions which are favorable for the planetesimal growth, and potentially allow for the subsequent formation of planets. Finally, we summarize this thesis in chapter 7. Many open questions still remain in current research field of planet formation in binary systems, and the current Kepler project provides an unprecedented opportunity for such researches. A comprehensive understanding of planets in binaries requires placing them in a bigger context to include the formation and evolution of stars and/or clusters.

  20. Multilevel Models for Binary Data

    ERIC Educational Resources Information Center

    Powers, Daniel A.

    2012-01-01

    The methods and models for categorical data analysis cover considerable ground, ranging from regression-type models for binary and binomial data, count data, to ordered and unordered polytomous variables, as well as regression models that mix qualitative and continuous data. This article focuses on methods for binary or binomial data, which are…

  1. Signature Visualization of Software Binaries

    SciTech Connect

    Panas, T

    2008-07-01

    In this paper we present work on the visualization of software binaries. In particular, we utilize ROSE, an open source compiler infrastructure, to pre-process software binaries, and we apply a landscape metaphor to visualize the signature of each binary (malware). We define the signature of a binary as a metric-based layout of the functions contained in the binary. In our initial experiment, we visualize the signatures of a series of computer worms that all originate from the same line. These visualizations are useful for a number of reasons. First, the images reveal how the archetype has evolved over a series of versions of one worm. Second, one can see the distinct changes between version. This allows the viewer to form conclusions about the development cycle of a particular worm.

  2. Binary Mixtures of Particles with Different Diffusivities Demix.

    PubMed

    Weber, Simon N; Weber, Christoph A; Frey, Erwin

    2016-02-01

    The influence of size differences, shape, mass, and persistent motion on phase separation in binary mixtures has been intensively studied. Here we focus on the exclusive role of diffusivity differences in binary mixtures of equal-sized particles. We find an effective attraction between the less diffusive particles, which are essentially caged in the surrounding species with the higher diffusion constant. This effect leads to phase separation for systems above a critical size: A single close-packed cluster made up of the less diffusive species emerges. Experiments for testing our predictions are outlined.

  3. Binary Mixtures of Particles with Different Diffusivities Demix.

    PubMed

    Weber, Simon N; Weber, Christoph A; Frey, Erwin

    2016-02-01

    The influence of size differences, shape, mass, and persistent motion on phase separation in binary mixtures has been intensively studied. Here we focus on the exclusive role of diffusivity differences in binary mixtures of equal-sized particles. We find an effective attraction between the less diffusive particles, which are essentially caged in the surrounding species with the higher diffusion constant. This effect leads to phase separation for systems above a critical size: A single close-packed cluster made up of the less diffusive species emerges. Experiments for testing our predictions are outlined. PMID:26894737

  4. BINARY ASTROMETRIC MICROLENSING WITH GAIA

    SciTech Connect

    Sajadian, Sedighe

    2015-04-15

    We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the Gaia observing strategy by considering (i) stellar-mass black holes, (ii) neutron stars, (iii) white dwarfs, and (iv) main-sequence stars as microlenses. The Gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is ∼10%–20%. By calculating the optical depth due to the mentioned stellar populations, the numbers of the binary astrometric microlensing events being observed with Gaia with detectable binary signatures, for the binary fraction of about 0.1, are estimated to be 6, 11, 77, and 1316, respectively. Consequently, Gaia can potentially specify the binary fractions of these massive stellar populations. However, the binary fraction of black holes measured with this method has a large uncertainty owing to a low number of the estimated events. Knowing the binary fractions in massive stellar populations helps with studying the gravitational waves. Moreover, we investigate the number of massive microlenses for which Gaia specifies masses through astrometric microlensing of single lenses toward the Galactic bulge. The resulting efficiencies of measuring the mass of mentioned populations are 9.8%, 2.9%, 1.2%, and 0.8%, respectively. The numbers of their astrometric microlensing events being observed in the Gaia era in which the lens mass can be inferred with the relative error less than 0.5 toward the Galactic bulge are estimated as 45, 34, 76, and 786, respectively. Hence, Gaia potentially gives us some information about the mass distribution of these massive stellar populations.

  5. EXPLORING A 'FLOW' OF HIGHLY ECCENTRIC BINARIES WITH KEPLER

    SciTech Connect

    Dong Subo; Katz, Boaz; Socrates, Aristotle

    2013-01-20

    With 16-month of Kepler data, 15 long-period (40-265 days) eclipsing binaries on highly eccentric orbits (minimum e between 0.5 and 0.85) are identified from their closely separated primary and secondary eclipses ({Delta}t{sub I,II} = 3-10 days). These systems confirm the existence of a previously hinted binary population situated near a constant angular momentum track at P(1 - e {sup 2}){sup 3/2} {approx} 15 days, close to the tidal circularization period P{sub circ}. They may be presently migrating due to tidal dissipation and form a steady-state 'flow' ({approx}1% of stars) feeding the close-binary population (few % of stars). If so, future Kepler data releases will reveal a growing number (dozens) of systems at longer periods, following dN/dlgP {proportional_to} P {sup 1/3} with increasing eccentricities reaching e {yields} 0.98 for P {yields} 1000 days. Radial-velocity follow-up of long-period eclipsing binaries with no secondary eclipses could offer a significantly larger sample. Orders of magnitude more (hundreds) may reveal their presence from periodic 'eccentricity pulses', such as tidal ellipsoidal variations near pericenter passages. Several new few-day-long eccentricity-pulse candidates with long periods (P = 25-80 days) are reported.

  6. Temporomandibular Joint, Closed

    MedlinePlus

    ... Oral Health > The Temporomandibular Joint, Closed The Temporomandibular Joint, Closed Main Content Title: The Temporomandibular Joint, Closed Description: The temporomandibular joint connects the lower ...

  7. Evolution of Small Binary Asteroids with the Binary YORP Effect

    NASA Astrophysics Data System (ADS)

    Frouard, Julien

    2013-05-01

    Abstract (2,250 Maximum Characters): Small, Near-Earth binaries are believed to be created following the fission of an asteroid spun up by the YORP effect. It is then believed that the YORP effect acting on the secondary (Binary YORP) increases or decreases the binary mutual distance on 10^5 yr timescales. How long this mechanism can apply is not yet fully understood. We investigate the binary orbital and rotational dynamics by using non-averaged, direct numerical simulations, taking into account the relative motion of two ellipsoids (primary and secondary) and the solar perturbation. We add the YORP force and torque on the orbital and rotational motion of the secondary. As a check of our code we obtain a ~ 7.2 cm/yr drift in semi-major axis for 1999 KW4 beta, consistent with the values obtained with former analytical studies. The synchronous rotation of the secondary is required for the Binary YORP to be effective. We investigate the synchronous lock of the secondary in function of different parameters ; mutual distance, shape of the secondary, and heliocentric orbit. For example we show that the secondary of 1999 KW4 can be synchronous only up to 7 Rp (primary radius), where the resonance becomes completely chaotic even for very small eccentricities. We use Gaussian Random Spheres to obtain various secondary shapes, and check the evolution of the binaries with the Binary YORP effect.

  8. VLSI binary updown counter

    NASA Technical Reports Server (NTRS)

    Truong, Trieu-Kie (Inventor); Hsu, In-Shek (Inventor); Reed, Irving S. (Inventor)

    1989-01-01

    A pipeline binary updown counter is comprised of simple stages that may be readily replicated. Each stage is defined by the Boolean logic equation: A(sub n)(t) = A(sub n)(t - 1) exclusive OR (U AND P(sub n)) inclusive OR (D AND Q(sub n)), where A(sub n)(t) denotes the value of the nth bit at time t. The input to the counter has three values represented by two binary signals U and D such that if both are zero, the input is zero, if U = 0 and D = 1, the input is -1 and if U = 1 and D = 0, the input is +1. P(sub n) represents a product of A(sub k)'s for 1 is less than or equal to k is less than or equal to -1, while Q(sub n) represents the product of bar A's for 1 is less than or equal to K is less than or equal to n - 1, where bar A(sub k) is the complement of A(sub k) and P(sub n) and Q(sub n) are expressed as the following two equations: P(sub n) = A(sub n - 1) A(sub n - 2)...A(sub 1) and Q(sub n) = bar A(sub n - 1) bar A(sub n - 2)...bar A(sub 1), which can be written in recursive form as P(sub n) = P(sub n - 1) AND bar A(sub n - 1) and Q(sub n) = Q(sub n - 1) AND bar A(sub n - 1) with the initial values P(sub 1) = 1 and Q(sub 1) = 1.

  9. White dwarf binaries and the gravitational wave foreground

    NASA Astrophysics Data System (ADS)

    Benacquista, Matthew

    2016-02-01

    Galactic white dwarf binaries will be an abundant source of gravitational waves in the mHz frequency band of space-based detectors such as eLISA. A few thousand to a few tens of thousands of these systems will be individually resolvable by eLISA, depending on the final detector configuration. The remaining tens of millions of close white dwarf binaries will create an unresolvable anisotropic foreground of gravitational waves that will be comparable to the instrument noise of eLISA at frequencies below about a mHz. Both the resolvable binaries and the foreground can be used to better understand this population. Careful choice of the initial orientation of eLISA can mitigate this foreground in searches for other sources.

  10. Open cluster evolutions in binary system: How they dissolved

    NASA Astrophysics Data System (ADS)

    Priyatikanto, R.; Arifyanto, M. I.; Wulandari, H. R. T.

    2014-03-01

    Binarity among stellar clusters in galaxy is such a reality which has been realized for a long time, but still hides several questions and problems to be solved. Some of binary star clusters are formed by close encounter, but the others are formed together from similar womb. Some of them undergo separation process, while the others are in the middle of merger toward common future. The products of merger binary star cluster have typical characteristics which differ from solo clusters, especially in their spatial distribution and their stellar members kinematics. On the other hand, these merger products still have to face dissolving processes triggered by both internal and external factors. In this study, we performed N-body simulations of merger binary clusters with different initial conditions. After merging, these clusters dissolve with greater mass-loss rate because of their angular momentum. These rotating clusters also experience more deceleration caused by external tidal field.

  11. Content identification: binary content fingerprinting versus binary content encoding

    NASA Astrophysics Data System (ADS)

    Ferdowsi, Sohrab; Voloshynovskiy, Svyatoslav; Kostadinov, Dimche

    2014-02-01

    In this work, we address the problem of content identification. We consider content identification as a special case of multiclass classification. The conventional approach towards identification is based on content fingerprinting where a short binary content description known as a fingerprint is extracted from the content. We propose an alternative solution based on elements of machine learning theory and digital communications. Similar to binary content fingerprinting, binary content representation is generated based on a set of trained binary classifiers. We consider several training/encoding strategies and demonstrate that the proposed system can achieve the upper theoretical performance limits of content identification. The experimental results were carried out both on a synthetic dataset with different parameters and the FAMOS dataset of microstructures from consumer packages.

  12. Very wide binary stars as the primary source of stellar collisions in the galaxy

    SciTech Connect

    Kaib, Nathan A.; Raymond, Sean N.

    2014-02-20

    We present numerical simulations modeling the orbital evolution of very wide binaries, pairs of stars separated by over ∼10{sup 3} AU. Due to perturbations from other passing stars and the Milky Way's tide, the orbits of very wide binary stars occasionally become extremely eccentric, which forces close encounters between the companion stars. We show that this process causes a stellar collision between very wide binary companion stars once every 1000-7500 yr on average in the Milky Way. One of the main uncertainties in this collision rate is the amount of energy dissipated by dynamic tides during close (but not collisional) periastron passages. This dissipation presents a dynamical barrier to stellar collisions and can instead transform very wide binaries into close or contact binaries. However, for any plausible tidal dissipation model, very wide binary stars are an unrealized, and potentially the dominant, source of stellar collisions in our Galaxy. Such collisions should occur throughout the thin disk of the Milky Way. Stellar collisions within very wide binaries should yield a small population of single, Li-depleted, rapidly rotating massive stars.

  13. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1997-01-01

    Electrophoresis has long been recognized as an effective analytic technique for the separation of proteins and other charged species, however attempts at scaling up to accommodate commercial volumes have met with limited success. In this report we describe a novel electrophoretic separation technique - Binary Oscillatory Crossflow Electrophoresis (BOCE). Numerical simulations indicate that the technique has the potential for preparative scale throughputs with high resolution, while simultaneously avoiding many problems common to conventional electrophoresis. The technique utilizes the interaction of an oscillatory electric field and a transverse oscillatory shear flow to create an active binary filter for the separation of charged protein species. An oscillatory electric field is applied across the narrow gap of a rectangular channel inducing a periodic motion of charged protein species. The amplitude of this motion depends on the dimensionless electrophoretic mobility, alpha = E(sub o)mu/(omega)d, where E(sub o) is the amplitude of the electric field oscillations, mu is the dimensional mobility, omega is the angular frequency of oscillation and d is the channel gap width. An oscillatory shear flow is induced along the length of the channel resulting in the separation of species with different mobilities. We present a model that predicts the oscillatory behavior of charged species and allows estimation of both the magnitude of the induced convective velocity and the effective diffusivity as a function of a in infinitely long channels. Numerical results indicate that in addition to the mobility dependence, the steady state behavior of solute species may be strongly affected by oscillating fluid into and out of the active electric field region at the ends of the cell. The effect is most pronounced using time dependent shear flows of the same frequency (cos((omega)t)) flow mode) as the electric field oscillations. Under such conditions, experiments indicate that

  14. A Link Between Massive Binary Stars and Non-thermal Radio Emission

    NASA Astrophysics Data System (ADS)

    Wallace, Debra

    1999-07-01

    Non-thermal radio emission in Wolf-Rayet {WR} stars is explained in terms of synchrotron emission from shocks in the wind. For single star models, the shocks arise from instabilities in the wind itself, whereas in binary models, the shocks form at the wind-wind interaction zone. In Niemela et al. 1998 {from WFPC2 data}, we support the binary theory, for two WR stars, linking the non-thermal emission with the colliding wind region. Before we can conclusively link non- thermal emission to binarity, we must demonstrate that all non-thermal emitters are binary, and that all thermal emitters are either single stars or binary systems with separations that are either too wide or too close to result in a wind-wind interaction that produces shocks. We cannot yet conclusively state this because WFPC2 does not resolve binaries with separations less than about 0.100''. We propose to use the FGS to observe 9 non-thermal and 9 thermal WR stars to search for binary companions. The FGS ca n resolve angular separations as s mall as .007''. If the non-thermal stars are resolved as binaries and the thermal emitters are determined to be single, the single star theory of non-thermal emission can be disavowed. Co-latterally, we will have demonstrated a new method of detecting massive binaries, and, for all WR stars, we will establish a more accurate binary incidence rate.

  15. The disruption of multiplanet systems through resonance with a binary orbit.

    PubMed

    Touma, Jihad R; Sridhar, S

    2015-08-27

    Most exoplanetary systems in binary stars are of S-type, and consist of one or more planets orbiting a primary star with a wide binary stellar companion. Planetary eccentricities and mutual inclinations can be large, perhaps forced gravitationally by the binary companion. Earlier work on single planet systems appealed to the Kozai-Lidov instability wherein a sufficiently inclined binary orbit excites large-amplitude oscillations in the planet's eccentricity and inclination. The instability, however, can be quenched by many agents that induce fast orbital precession, including mutual gravitational forces in a multiplanet system. Here we report that orbital precession, which inhibits Kozai-Lidov cycling in a multiplanet system, can become fast enough to resonate with the orbital motion of a distant binary companion. Resonant binary forcing results in dramatic outcomes ranging from the excitation of large planetary eccentricities and mutual inclinations to total disruption. Processes such as planetary migration can bring an initially non-resonant system into resonance. As it does not require special physical or initial conditions, binary resonant driving is generic and may have altered the architecture of many multiplanet systems. It can also weaken the multiplanet occurrence rate in wide binaries, and affect planet formation in close binaries. PMID:26310763

  16. The disruption of multiplanet systems through resonance with a binary orbit.

    PubMed

    Touma, Jihad R; Sridhar, S

    2015-08-27

    Most exoplanetary systems in binary stars are of S-type, and consist of one or more planets orbiting a primary star with a wide binary stellar companion. Planetary eccentricities and mutual inclinations can be large, perhaps forced gravitationally by the binary companion. Earlier work on single planet systems appealed to the Kozai-Lidov instability wherein a sufficiently inclined binary orbit excites large-amplitude oscillations in the planet's eccentricity and inclination. The instability, however, can be quenched by many agents that induce fast orbital precession, including mutual gravitational forces in a multiplanet system. Here we report that orbital precession, which inhibits Kozai-Lidov cycling in a multiplanet system, can become fast enough to resonate with the orbital motion of a distant binary companion. Resonant binary forcing results in dramatic outcomes ranging from the excitation of large planetary eccentricities and mutual inclinations to total disruption. Processes such as planetary migration can bring an initially non-resonant system into resonance. As it does not require special physical or initial conditions, binary resonant driving is generic and may have altered the architecture of many multiplanet systems. It can also weaken the multiplanet occurrence rate in wide binaries, and affect planet formation in close binaries.

  17. Markov Chain Monte-Carlo Orbit Computation for Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Oszkiewicz, D.; Hestroffer, D.; Pedro, David C.

    2013-11-01

    We present a novel method of orbit computation for resolved binary asteroids. The method combines the Thiele, Innes, van den Bos method with a Markov chain Monte Carlo technique (MCMC). The classical Thiele-van den Bos method has been commonly used in multiple applications before, including orbits of binary stars and asteroids; conversely this novel method can be used for the analysis of binary stars, and of other gravitationally bound binaries. The method requires a minimum of three observations (observing times and relative positions - Cartesian or polar) made at the same tangent plane - or close enough for enabling a first approximation. Further, the use of the MCMC technique for statistical inversion yields the whole bundle of possible orbits, including the one that is most probable. In this new method, we make use of the Metropolis-Hastings algorithm to sample the parameters of the Thiele-van den Bos method, that is the orbital period (or equivalently the double areal constant) together with three randomly selected observations from the same tangent plane. The observations are sampled within their observational errors (with an assumed distribution) and the orbital period is the only parameter that has to be tuned during the sampling procedure. We run multiple chains to ensure that the parameter phase space is well sampled and that the solutions have converged. After the sampling is completed we perform convergence diagnostics. The main advantage of the novel approach is that the orbital period does not need to be known in advance and the entire region of possible orbital solutions is sampled resulting in a maximum likelihood solution and the confidence regions. We have tested the new method on several known binary asteroids and conclude a good agreement with the results obtained with other methods. The new method has been implemented into the Gaia DPAC data reduction pipeline and can be used to confirm the binary nature of a suspected system, and for deriving

  18. ROTATIONAL VELOCITIES OF INDIVIDUAL COMPONENTS IN VERY LOW MASS BINARIES

    SciTech Connect

    Konopacky, Q. M.; Macintosh, B. A.; Ghez, A. M.; Fabrycky, D. C.; White, R. J.; Barman, T. S.; Rice, E. L.; Hallinan, G.; Duchene, G. E-mail: konopacky@di.utoronto.ca E-mail: fabrycky@ucolick.org E-mail: barman@lowell.edu E-mail: gh@astro.caltech.edu

    2012-05-01

    We present rotational velocities for individual components of 11 very low mass (VLM) binaries with spectral types between M7 and L7.5. These results are based on observations taken with the near-infrared spectrograph, NIRSPEC, and the Keck II laser guide star adaptive optics system. We find that the observed sources tend to be rapid rotators (v sin i > 10 km s{sup -1}), consistent with previous seeing-limited measurements of VLM objects. The two sources with the largest v sin i, LP 349-25B and HD 130948C, are rotating at {approx}30% of their break-up speed, and are among the most rapidly rotating VLM objects known. Furthermore, five binary systems, all with orbital semimajor axes {approx}<3.5 AU, have component v sin i values that differ by greater than 3{sigma}. To bring the binary components with discrepant rotational velocities into agreement would require the rotational axes to be inclined with respect to each other, and that at least one component is inclined with respect to the orbital plane. Alternatively, each component could be rotating at a different rate, even though they have similar spectral types. Both differing rotational velocities and inclinations have implications for binary star formation and evolution. We also investigate possible dynamical evolution in the triple system HD 130948A-BC. The close binary brown dwarfs B and C have significantly different v sin i values. We demonstrate that components B and C could have been torqued into misalignment by the primary star, A, via orbital precession. Such a scenario can also be applied to another triple system in our sample, GJ 569A-Bab. Interactions such as these may play an important role in the dynamical evolution of VLM binaries. Finally, we note that two of the binaries with large differences in component v sin i, LP 349-25AB and 2MASS 0746+20AB, are also known radio sources.

  19. X-RAY EMISSION FROM THE BINARY CENTRAL STARS OF THE PLANETARY NEBULAE HFG 1, DS 1, AND LOTR 5

    SciTech Connect

    Montez, Rodolfo; Kastner, Joel H.; De Marco, Orsola; Chu, You-Hua

    2010-10-01

    Close binary systems undergoing mass transfer or common envelope interactions can account for the morphological properties of some planetary nebulae. The search for close binary companions in planetary nebulae is hindered by the difficulty of detecting cool, late-type, main-sequence companions in binary systems with hot pre-white-dwarf primaries. However, models of binary planetary nebula progenitor systems predict that mass accretion or tidal interactions can induce rapid rotation in the companion, leading to X-ray-emitting coronae. To test such models, we have searched for, and detected, X-ray emission from three binary central stars within planetary nebulae: the post-common envelope close binaries in HFG 1 and DS 1 consisting of O-type subdwarfs with late-type, main-sequence companions and the binary system in LoTr 5 consisting of O-type subdwarf and rapidly rotating, late-type giant companion. The X-ray emission in each case is best characterized by spectral models consisting of two optically thin thermal plasma components with characteristic temperatures of {approx}10 MK and 15-40 MK and total X-ray luminosities {approx}10{sup 30} erg s{sup -1}. We consider the possible origin of the X-ray emission from these binary systems and conclude that the most likely origin is, in each case, a corona around the late-type companion, as predicted by models of interacting binaries.

  20. The properties of close multiple stars

    NASA Technical Reports Server (NTRS)

    Fekel, F. C., Jr.

    1981-01-01

    A reexamination of the properties of close multiple systems is conducted, taking into account recent numerical, analytical, and observational results. The orbital elements of 43 spectroscopic multiple systems are presented in a table. Tables with photometry data of the systems and data describing their properties are also provided. Attention is given to period ratios, mass ratios, orbital coplanarity, stability, lithium abundances and age estimates, and prospects of future observations. Numerical studies indicate that fragmentation produces binary components with mass ratios usually close to 1.0, while fission usually produces mass ratios in the range 0.1-0.5. Using analytical stability criteria, all 27 close multiple systems considered are stable if they are corotating. If they are counter-rotating, four systems are possibly unstable. However, other factors suggest that even these four are probably stable. The solar-type close multiple systems ranged in age from 100 million years to 2,000 million years.

  1. Measuring the redshift factor in binary black hole simulations

    NASA Astrophysics Data System (ADS)

    Zimmerman, Aaron; Lewis, Adam; Pfeiffer, Harald

    2016-03-01

    The redshift factor z is an invariant quantity of fundamental interest in Post-Newtonian and self-force descriptions of circular binaries. It allows for interconnections between each theory, and plays a central role in the Laws of Binary Black Hole Mechanics, which link local quantities to asymptotic measures of energy and angular momentum in these systems. Through these laws, the redshift factor is conjectured to have a close relation to the surface gravity of the event horizons of black holes in circular orbits. We have implemented a novel method for extracting the redshift factor on apparent horizons in numerical simulations of quasicircular binary inspirals. Our results confirm the conjectured relationship between z and the surface gravity of the holes. This redshift factor allows us to test PN and self-force predictions for z in spacetimes where the binary is only approximately circular, and allows for an array of new comparisons between analytic approximations and numerical simulations. I will present our new method, our initial results in using z to verify the Laws of Binary Black Holes Mechanics, and discuss future directions for this work.

  2. Relating binary-star planetary systems to central configurations

    NASA Astrophysics Data System (ADS)

    Veras, Dimitri

    2016-11-01

    Binary-star exoplanetary systems are now known to be common, for both wide and close binaries. However, their orbital evolution is generally unsolvable. Special cases of the N-body problem which are in fact completely solvable include dynamical architectures known as central configurations. Here, I utilize recent advances in our knowledge of central configurations to assess the plausibility of linking them to coplanar exoplanetary binary systems. By simply restricting constituent masses to be within stellar or substellar ranges characteristic of planetary systems, I find that (i) this constraint reduces by over 90 per cent the phase space in which central configurations may occur, (ii) both equal-mass and unequal-mass binary stars admit central configurations, (iii) these configurations effectively represent different geometrical extensions of the Sun-Jupiter-Trojan-like architecture, (iv) deviations from these geometries are no greater than 10°, and (v) the deviation increases as the substellar masses increase. This study may help restrict future stability analyses to architectures which resemble exoplanetary systems, and might hint at where observers may discover dust, asteroids and/or planets in binary-star systems.

  3. Triple-star Candidates among the Kepler Binaries

    NASA Astrophysics Data System (ADS)

    Rappaport, S.; Deck, K.; Levine, A.; Borkovits, T.; Carter, J.; El Mellah, I.; Sanchis-Ojeda, R.; Kalomeni, B.

    2013-05-01

    We present the results of a search through the photometric database of Kepler eclipsing binaries looking for evidence of hierarchical triple-star systems. The presence of a third star orbiting the binary can be inferred from eclipse timing variations. We apply a simple algorithm in an automated determination of the eclipse times for all 2157 binaries. The "calculated" eclipse times, based on a constant period model, are subtracted from those observed. The resulting O - C (observed minus calculated times) curves are then visually inspected for periodicities in order to find triple-star candidates. After eliminating false positives due to the beat frequency between the ~1/2 hr Kepler cadence and the binary period, 39 candidate triple systems were identified. The periodic O - C curves for these candidates were then fit for contributions from both the classical Roemer delay and so-called physical delay, in an attempt to extract a number of the system parameters of the triple. We discuss the limitations of the information that can be inferred from these O - C curves without further supplemental input, e.g., ground-based spectroscopy. Based on the limited range of orbital periods for the triple-star systems to which this search is sensitive, we can extrapolate to estimate that at least 20% of all close binaries have tertiary companions.

  4. TRIPLE-STAR CANDIDATES AMONG THE KEPLER BINARIES

    SciTech Connect

    Rappaport, S.; Deck, K.; Sanchis-Ojeda, R.; Levine, A.; Borkovits, T.; Carter, J.; El Mellah, I.; Kalomeni, B. E-mail: kdeck@mit.edu E-mail: aml@space.mit.edu E-mail: jacarter@cfa.harvard.edu

    2013-05-01

    We present the results of a search through the photometric database of Kepler eclipsing binaries looking for evidence of hierarchical triple-star systems. The presence of a third star orbiting the binary can be inferred from eclipse timing variations. We apply a simple algorithm in an automated determination of the eclipse times for all 2157 binaries. The ''calculated'' eclipse times, based on a constant period model, are subtracted from those observed. The resulting O - C (observed minus calculated times) curves are then visually inspected for periodicities in order to find triple-star candidates. After eliminating false positives due to the beat frequency between the {approx}1/2 hr Kepler cadence and the binary period, 39 candidate triple systems were identified. The periodic O - C curves for these candidates were then fit for contributions from both the classical Roemer delay and so-called physical delay, in an attempt to extract a number of the system parameters of the triple. We discuss the limitations of the information that can be inferred from these O - C curves without further supplemental input, e.g., ground-based spectroscopy. Based on the limited range of orbital periods for the triple-star systems to which this search is sensitive, we can extrapolate to estimate that at least 20% of all close binaries have tertiary companions.

  5. An adaptable binary entropy coder

    NASA Technical Reports Server (NTRS)

    Kiely, A.; Klimesh, M.

    2001-01-01

    We present a novel entropy coding technique which is based on recursive interleaving of variable-to-variable length binary source codes. We discuss code design and performance estimation methods, as well as practical encoding and decoding algorithms.

  6. Cryptography with DNA binary strands.

    PubMed

    Leier, A; Richter, C; Banzhaf, W; Rauhe, H

    2000-06-01

    Biotechnological methods can be used for cryptography. Here two different cryptographic approaches based on DNA binary strands are shown. The first approach shows how DNA binary strands can be used for steganography, a technique of encryption by information hiding, to provide rapid encryption and decryption. It is shown that DNA steganography based on DNA binary strands is secure under the assumption that an interceptor has the same technological capabilities as sender and receiver of encrypted messages. The second approach shown here is based on steganography and a method of graphical subtraction of binary gel-images. It can be used to constitute a molecular checksum and can be combined with the first approach to support encryption. DNA cryptography might become of practical relevance in the context of labelling organic and inorganic materials with DNA 'barcodes'.

  7. CHAOTIC ZONES AROUND GRAVITATING BINARIES

    SciTech Connect

    Shevchenko, Ivan I.

    2015-01-20

    The extent of the continuous zone of chaotic orbits of a small-mass tertiary around a system of two gravitationally bound primaries of comparable masses (a binary star, a binary black hole, a binary asteroid, etc.) is estimated analytically, as a function of the tertiary's orbital eccentricity. The separatrix map theory is used to demonstrate that the central continuous chaos zone emerges (above a threshold in the primaries' mass ratio) due to overlapping of the orbital resonances corresponding to the integer ratios p:1 between the tertiary and the central binary periods. In this zone, the unlimited chaotic orbital diffusion of the tertiary takes place, up to its ejection from the system. The primaries' mass ratio, above which such a chaotic zone is universally present at all initial eccentricities of the tertiary, is estimated. The diversity of the observed orbital configurations of biplanetary and circumbinary exosystems is shown to be in accord with the existence of the primaries' mass parameter threshold.

  8. Separation in 5 Msun Binaries

    NASA Astrophysics Data System (ADS)

    Evans, Nancy R.; Bond, H. E.; Schaefer, G.; Mason, B. D.; Karovska, M.; Tingle, E.

    2013-01-01

    Cepheids (5 Msun stars) provide an excellent sample for determining the binary properties of fairly massive stars. International Ultraviolet Explorer (IUE) observations of Cepheids brighter than 8th magnitude resulted in a list of ALL companions more massive than 2.0 Msun uniformly sensitive to all separations. Hubble Space Telescope Wide Field Camera 3 (WFC3) has resolved three of these binaries (Eta Aql, S Nor, and V659 Cen). Combining these separations with orbital data in the literature, we derive an unbiased distribution of binary separations for a sample of 18 Cepheids, and also a distribution of mass ratios. The distribution of orbital periods shows that the 5 Msun binaries prefer shorter periods than 1 Msun stars, reflecting differences in star formation processes.

  9. Simulating relativistic binaries with Whisky

    NASA Astrophysics Data System (ADS)

    Baiotti, L.

    We report about our first tests and results in simulating the last phase of the coalescence and the merger of binary relativistic stars. The simulations were performed using our code Whisky and mesh refinement through the Carpet driver.

  10. A wide binary trigger for white dwarf pollution

    NASA Astrophysics Data System (ADS)

    Bonsor, Amy; Veras, Dimitri

    2015-11-01

    Metal pollution in white dwarf atmospheres is commonly assumed to be a signature of remnant planetary systems. Most explanations for this pollution predict a sharp decrease in the number of polluted systems with white dwarf cooling age. Observations do not confirm this trend, and metal pollution in old (1-5 Gyr) white dwarfs is difficult to explain. We propose an alternative, time-independent mechanism to produce the white dwarf pollution. The orbit of a wide binary companion can be perturbed by Galactic tides, approaching close to the primary star for the first time after billions of years of evolution on the white dwarf branch. We show that such a close approach perturbs a planetary system orbiting the white dwarf, scattering planetesimals on to star-grazing orbits, in a manner that could pollute the white dwarf's atmosphere. Our estimates find that this mechanism is likely to contribute to metal pollution, alongside other mechanisms, in up to a few per cent of an observed sample of white dwarfs with wide binary companions, independent of white dwarf age. This age independence is the key difference between this wide binary mechanism and others mechanisms suggested in the literature to explain white dwarf pollution. Current observational samples are not large enough to assess whether this mechanism makes a significant contribution to the population of polluted white dwarfs, for which better constraints on the wide binary population are required, such as those that will be obtained in the near future with Gaia.

  11. HIGH FILL-OUT, EXTREME MASS RATIO OVERCONTACT BINARY SYSTEMS. X. THE NEWLY DISCOVERED BINARY XY LEONIS MINORIS

    SciTech Connect

    Qian, S.-B.; Liu, L.; Zhu, L.-Y.; He, J.-J.; Bernasconi, L. E-mail: yygcn@163.com

    2011-05-15

    The newly discovered short-period close binary star, XY LMi, has been monitored photometrically since 2006. Its light curves are typical EW-type light curves and show complete eclipses with durations of about 80 minutes. Photometric solutions were determined through an analysis of the complete B, V, R, and I light curves using the 2003 version of the Wilson-Devinney code. XY LMi is a high fill-out, extreme mass ratio overcontact binary system with a mass ratio of q = 0.148 and a fill-out factor of f = 74.1%, suggesting that it is in the late evolutionary stage of late-type tidal-locked binary stars. As observed in other overcontact binary stars, evidence for the presence of two dark spots on both components is given. Based on our 19 epochs of eclipse times, we found that the orbital period of the overcontact binary is decreasing continuously at a rate of dP/dt = -1.67 x 10{sup -7} days yr{sup -1}, which may be caused by mass transfer from the primary to the secondary and/or angular momentum loss via magnetic stellar wind. The decrease of the orbital period may result in the increase of the fill-out, and finally, it will evolve into a single rapid-rotation star when the fluid surface reaches the outer critical Roche lobe.

  12. Observations of the eclipsing binary b Persei

    NASA Astrophysics Data System (ADS)

    Templeton, Matthew R.

    2015-01-01

    Dr. Robert Zavala (USNO-Flagstaff) et al. request V time-series observations of the bright variable star b Persei 7-21 January 2015 UT, in hopes of catching a predicted eclipse on January 15. This is a follow-up to the February 2013 campaign announced in Alert Notice 476, and will be used as a photometric comparison for upcoming interferometric observations with the Navy Precision Optical Interferometer (NPOI) in Arizona. b Per (V=4.598, B-V=0.054) is ideal for photoelectric photometers or DSLR cameras. Telescopic CCD observers may observe by stopping down larger apertures. Comparison and check stars assigned by PI: Comp: SAO 24412, V=4.285, B-V = -0.013; Check: SAO 24512, V=5.19, B-V = -0.05. From the PI: "[W]e wanted to try and involve AAVSO observers in a follow up to our successful detection of the b Persei eclipse of Feb 2013, AAVSO Alert Notice 476 and Special Notice 333. Our goal now is to get good time resolution photometry as the third star passes in front of the close ellipsoidal binary. The potential for multiple eclipses exists. The close binary has a 1.5 day orbital period, and the eclipsing C component requires about 4 days to pass across the close binary pair. The primary eclipse depth is 0.15 magnitude. Photometry to 0.02 or 0.03 mags would be fine to detect this eclipse. Eclipse prediction date (JD 2457033.79 = 2015 01 11 UT, ~+/- 1 day) is based on one orbital period from the 2013 eclipse." More information is available at PI's b Persei eclipse web page: http://inside.warren-wilson.edu/~dcollins/bPersei/. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and information on the targets.

  13. Unsupervised learning of binary vectors

    NASA Astrophysics Data System (ADS)

    Copelli Lopes da Silva, Mauro

    In this thesis, unsupervised learning of binary vectors from data is studied using methods from Statistical Mechanics of disordered systems. In the model, data vectors are distributed according to a single symmetry-breaking direction. The aim of unsupervised learning is to provide a good approximation to this direction. The difference with respect to previous studies is the knowledge that this preferential direction has binary components. It is shown that sampling from the posterior distribution (Gibbs learning) leads, for general smooth distributions, to an exponentially fast approach to perfect learning in the asymptotic limit of large number of examples. If the distribution is non-smooth, then first order phase transitions to perfect learning are expected. In the limit of poor performance, a second order phase transition ("retarded learning") is predicted to occur if the data distribution is not biased. Using concepts from Bayesian inference, the center of mass of the Gibbs ensemble is shown to have maximal average (Bayes-optimal) performance. This upper bound for continuous vectors is extended to a discrete space, resulting in the clipped center of mass of the Gibbs ensemble having maximal average performance among the binary vectors. To calculate the performance of this best binary vector, the geometric properties of the center of mass of binary vectors are studied. The surprising result is found that the center of mass of infinite binary vectors which obey some simple constraints, is again a binary vector. When disorder is taken into account in the calculation, however, a vector with continuous components is obtained. The performance of the best binary vector is calculated and shown to always lie above that of Gibbs learning and below the Bayes-optimal performance. Making use of a variational approach under the replica symmetric ansatz, an optimal potential is constructed in the limits of zero temperature and mutual overlap 1. Minimization of this potential

  14. Characterization of Trans-Neptunian Binaries

    NASA Astrophysics Data System (ADS)

    Dmitrievna Kovalenko, Irina; Doressoundiram, Alain

    2016-10-01

    During the "TNOs are Cool: A Survey of the Trans-Neptunian Region" two important physical properties, such as size and albedo, have been obtained from Herschel and Spitzer thermal emission measurements. In this present work we describe an analysis of 28 binary and 2 triple objects related to the "TNOs are cool" project. Firstly, this analysis contains a comparison of multiples with other TNOs by their albedo and diameter characteristics. Secondly, an analysis on correlations between physical and orbital parameters is performed.The knowledge of size allows to estimate the bulk density, which is a crucial parameter containing information on the internal structure of TNOs. Hence, the density estimation problem requires known mass, whose measurement is only possible if the object has a satellite with a known orbit. Unfortunately, from our dataset of binaries only few of them have a full orbit solution and, consequently, a derived bulk density. The lack of observations of such distant objects leads to difficulties in close satellite's orbit determination. A statistical approach, based on a Monte-Carlo Markov chain global optimisation algorithm, is proposed for this problem.

  15. Planets in Evolved Binary Systems

    NASA Astrophysics Data System (ADS)

    Perets, Hagai B.

    2011-03-01

    Exo-planets are typically thought to form in protoplanetary disks left over from protostellar disk of their newly formed host star. However, additional planetary formation and evolution routes may exist in old evolved binary systems. Here we discuss the implications of binary stellar evolution on planetary systems in such environments. In these binary systems stellar evolution could lead to the formation of symbiotic stars, where mass is lost from one star and could be transferred to its binary companion, and may form an accretion disk around it. This raises the possibility that such a disk could provide the necessary environment for the formation of a new, second generation of planets in both circumstellar or circumbinary configurations. Pre-existing first generation planets surviving the post-MS evolution of such systems would be dynamically effected by the mass loss in the systems and may also interact with the newly formed disk. Such planets and/or planetesimals may also serve as seeds for the formation of the second generation planets, and/or interact with them, possibly forming atypical planetary systems. Second generation planetary systems should be typically found in white dwarf binary systems, and may show various observational signatures. Most notably, second generation planets could form in environment which are inaccessible, or less favorable, for first generation planets. The orbital phase space available for the second generation planets could be forbidden (in terms of the system stability) to first generation planets in the pre-evolved progenitor binaries. In addition planets could form in metal poor environments such as globular clusters and/or in double compact object binaries. Observations of exo-planets in such forbidden or unfavorable regions could possibly serve to uniquely identify their second generation character. Finally, we point out a few observed candidate second generation planetary systems, including Gl 86, HD 27442 and all of the

  16. Synchronization of magnetic stars in binary systems

    NASA Technical Reports Server (NTRS)

    Lamb, F. K.; Aly, J.-J.; Cook, M. C.; Lamb, D. Q.

    1983-01-01

    Asynchronous rotation of magnetic stars in close binary systems drives substantial field-aligned electrical currents between the magnetic star and its companion. The resulting magnetohydrodynamic torque is able to account for the heretofore unexplained synchronous rotation of the strongly magnetic degenerate dwarf component in systems like AM Her, VV Pup, AN UMa, and EF Eri as well as the magnetic A type component in systems like HD 98088 and 41 Tauri. The electric fields produced by even a small asynchronism are large and may accelerate some electrons to high energies, producing radio emission. The total energy dissipation rate in systems with degenerate dwarf spin periods as short as 1 minute may reach 10 to the 33rd ergs/s. Total luminosities of this order may be a characteristic feature of such systems.

  17. Conjugating binary systems for spacecraft thermal control

    NASA Technical Reports Server (NTRS)

    Grodzka, Philomena G.; Dean, William G.; Sisk, Lori A.; Karu, Zain S.

    1989-01-01

    The materials search was directed to liquid pairs which can form hydrogen bonds of just the right strength, i.e., strong enough to give a high heat of mixing, but weak enough to enable phase change to occur. The cursory studies performed in the area of additive effects indicate that Conjugating Binary (CB) performance can probably be fine-tuned by this means. The Fluid Loop Test Systems (FLTS) tests of candidate CBs indicate that the systems Triethylamine (TEA)/water and propionaldehyde/water show close to the ideal, reversible behavior, at least initially. The Quick Screening Tests QSTs and FLTS tests, however, both suffer from rather severe static due either to inadequate stirring or temperature control. Thus it is not possible to adequately evaluate less than ideal CB performers. Less than ideal performers, it should be noted, may have features that make them better practical CBs than ideal performers. Improvement of the evaluation instrumentation is thus indicated.

  18. Lyapunov timescales and black hole binaries

    NASA Astrophysics Data System (ADS)

    Cornish, Neil J.; Levin, Janna

    2003-05-01

    Black hole binaries support unstable orbits at very close separations. In the simplest case of geodesics around a Schwarzschild black hole the orbits, though unstable, are regular. Under perturbation the unstable orbits can become the locus of chaos. All unstable orbits, whether regular or chaotic, can be quantified by their Lyapunov exponents. The exponents are observationally relevant since the phase of gravitational waves can decohere in a Lyapunov time. If the timescale for dissipation due to gravitational waves is shorter than the Lyapunov time, chaos will be damped and essentially unobservable. We find that the two timescales can be comparable. We emphasize that the Lyapunov exponents must only be used cautiously for several reasons: they are relative and depend on the coordinate system used, they vary from orbit to orbit, and finally they can be deceptively diluted by transient behaviour for orbits which pass in and out of unstable regions.

  19. Nucleation of bubbles in binary fluids

    NASA Astrophysics Data System (ADS)

    Talanquer, V.; Oxtoby, David W.

    1995-02-01

    We have applied density functional methods to predict the nucleation rates of bubbles in superheated, stretched, or supersaturated binary fluid mixtures. Our model uses Lennard-Jones mixtures, with mixing rules chosen to allow either ideal or nonideal solution behavior. Deviations from the predictions of classical nucleation theory are in general quite large, with the locus of observable bubble nucleation (the kinetic stability limit) following the spinodal (the thermodynamic stability limit) reasonably closely. Comparisons are made with a variety of experiments, and puzzling earlier results are explained, such as the increase in solubility of some gases with temperature at the kinetic stability limit. Further experiments are needed to explore the variety of behavior predicted by the present calculations.

  20. Spinning compact binary dynamics and chameleon orbits

    NASA Astrophysics Data System (ADS)

    Gergely, László Árpád; Keresztes, Zoltán

    2015-01-01

    We analyze the conservative evolution of spinning compact binaries to second post-Newtonian (2PN) order accuracy, with leading-order spin-orbit, spin-spin and mass quadrupole-monopole contributions included. As a main result we derive a closed system of first-order differential equations in a compact form, for a set of dimensionless variables encompassing both orbital elements and spin angles. These evolutions are constrained by conservation laws holding at 2PN order. As required by the generic theory of constrained dynamical systems we perform a consistency check and prove that the constraints are preserved by the evolution. We apply the formalism to show the existence of chameleon orbits, whose local, orbital parameters evolve from elliptic (in the Newtonian sense) near pericenter, towards hyperbolic at large distances. This behavior is consistent with the picture that general relativity predicts stronger gravity at short distances than Newtonian theory does.

  1. Binary drop coalescence in liquids

    NASA Astrophysics Data System (ADS)

    Kim, Jungyong

    Experiments on binary drop collisions within an index-matched liquid were conducted for Weber numbers (We) of 1-50 and collision angles of 15-80° below the horizontal. Drop pairs of water/glycerin mixture were injected into silicone oil and, due to gravitational effects, traveled on downward trajectories before colliding. A dual-field high-speed PIV measurement system was employed to quantify drop trajectories and overall collision conditions while simultaneously examining detailed velocity fields near the collision interface. In the We range examined, for equal size drops, both rebounding and coalescing behavior occurred. The drops coalesced for We > 10 and rebounded for We < 10, and this boundary was found to be insensitive to collision angle. Coalescence was found to result from a combination of vortical flow within drops and strong drop deformation characteristic of higher We. Flow through the centers of opposing ring vortices, strengthened by drop deformation, enhanced drainage of the thin film in the impact region, leading to film rupture and coalescence. The collision angle affected the eventual location of film rupture, with the rupture location moving higher in the thin film region as the collision angle increased. The film rupture location correlated closely with the location of maximum downward velocity in the thin film. The time between collision and rupture increases with We until We = 30. For We > 30, the time decreases as We increases. Unequal size drop collisions with drop size ratios (Ds/D L) of 0.7 and 0.5 were also examined. Coalescence occurs above We* = 11 similar to equal size drops. As drop size ratio decreases, the intervening film deforms more. If the velocity ratio uL/u s < 1, the deformed interface becomes flat before coalescence. The rupture location varies due to the asymmetry of the drops. As collision offset increases (B > 0), the film rupture time is shortened and mixing of the fluid from both drops is enhanced after coalescence

  2. Advancement and New Functionality of the Binary Star DataBase (BDB)

    NASA Astrophysics Data System (ADS)

    Malkov, O. Yu.; Kovaleva, D. A.; Kaygorodov, P. V.

    2016-06-01

    A new version of Binary star DataBase BDB (bdb.inasan.ru) has been released. It is much more flexible and quick than the previous version and offers full search capabilities on all parameters. New information is progressively added, in particular data from principal catalogues of close (spectroscopic, eclipsing, X-ray) binaries. A new interface has been completed, providing a more user-friendly navigation while retaining the multiple search and browsing capabilities.

  3. Electronic Textbook for Amateur Astronomers and Students "Binary Stars and Their Evolution"

    NASA Astrophysics Data System (ADS)

    Chinarova, L. L.

    Electronic textbook for members and supervisors of the Youth Academy of Sciences; schoolars and teachers; students of the first courses. Total volume of the printed version is 86pp. The textbook is devoted to 100-th Anniversary of Prof. V.P.Tsessevich (1907-1983). It contains the chapters: "Birth and Life of Stars"; "Main Types of Binary Stars and Their Characteristics"; "Complex Interactions in Close Binary Stars"; "Evolution of Binary Stars"; "Symbiotic Stars"; "Cataclysmic Variables"; "Literature". This textbook (in Russian) is freely accessible at the Internet site http://chinarova.pochta.ru.

  4. Life and light: exotic photosynthesis in binary and multiple-star systems.

    PubMed

    O'Malley-James, J T; Raven, J A; Cockell, C S; Greaves, J S

    2012-02-01

    The potential for Earth-like planets within binary/multiple-star systems to host photosynthetic life was evaluated by modeling the levels of photosynthetically active radiation (PAR) such planets receive. Combinations of M and G stars in (i) close-binary systems; (ii) wide-binary systems, and (iii) three-star systems were investigated, and a range of stable radiation environments were found to be possible. These environmental conditions allow for the possibility of familiar, but also more exotic, forms of photosynthetic life, such as IR photosynthesizers and organisms that are specialized for specific spectral niches.

  5. The Michigan Binary Star Program

    NASA Astrophysics Data System (ADS)

    Lindner, Rudi P.

    2007-07-01

    At the end of the nineteenth century, William J. Hussey and Robert G. Aitken, both at Lick Observatory, began a systematic search for unrecorded binary stars with the aid of the 12" and 36" refracting telescopes at Lick Observatory. Aitken's work (and book on binary stars) are well known, Hussey's contributions less so. In 1905 Hussey, a Michigan engineering graduate, returned to direct the Ann Arbor astronomy program, and immediately he began to design new instrumentation for the study of binary stars and to train potential observers. For a time, he spent six months a year at the La Plata Observatory, where he discovered a number of new pairs and decided upon a major southern hemisphere campaign. He spent a decade obtaining the lenses for a large refractor, through the vicissitudes of war and depression. Finally, he obtained a site in South Africa, a 26" refractor, and a small corps of observers, but he died in London en route to fulfill his dream. His right hand man, Richard Rossiter, established the observatory and spent the next thirty years discovering and measuring binary stars: his personal total is a record for the field. This talk is an account of the methods, results, and utility of the extraordinary binary star factory in the veldt.

  6. Searching for Spectroscopic Binaries within Transition Disk Objects

    NASA Astrophysics Data System (ADS)

    Kohn, Saul A.; Shkolnik, Evgenya L.; Weinberger, Alycia J.; Carlberg, Joleen K.; Llama, Joe

    2016-03-01

    Transition disks (TDs) are intermediate stage circumstellar disks characterized by an inner gap within the disk structure. To test whether these gaps may have been formed by closely orbiting, previously undetected stellar companions, we collected high-resolution optical spectra of 31 TD objects to search for spectroscopic binaries (SBs). Twenty-four of these objects are in Ophiuchus and seven are within the Coronet, Corona Australis, and Chameleon I star-forming regions. We measured radial velocities for multiple epochs, obtaining a median precision of 400 ms-1. We identified double-lined SB SSTc2d J163154.7-250324 in Ophiuchus, which we determined to be composed of a K7(±0.5) and a K9(±0.5) star, with orbital limits of a < 0.6 au and P < 150 days. This results in an SB fraction of {0.04}-0.03+0.12 in Ophiuchus, which is consistent with other spectroscopic surveys of non-TD objects in the region. This similarity suggests that TDs are not preferentially sculpted by the presence of close binaries and that planet formation around close binaries may take place over similar timescales to that around single stars. This paper is based on data gathered with the 6.5 m Clay Telescope located at Las Campanas Observatory, Chile.

  7. Eclipsing post-common envelope binaries from the Catalina surveys

    NASA Astrophysics Data System (ADS)

    Parsons, S. G.; Gänsicke, B. T.; Marsh, T. R.; Drake, A. J.; Dhillon, V. S.; Littlefair, S. P.; Pyrzas, S.; Rebassa-Mansergas, A.; Schreiber, M. R.

    2013-02-01

    We analyse the Catalina Real-time Transient Survey light curves of 835 spectroscopically confirmed white dwarf plus main-sequence binaries from the Sloan Digital Sky Survey (SDSS) with g < 19, in search of new eclipsing systems. We identify 29 eclipsing systems, 12 of which were previously unknown. This brings the total number of eclipsing white dwarf plus main-sequence binaries to 49. Our set of new eclipsing systems contains two with periods of 1.9 and 2.3 d, making them the longest period eclipsing white dwarf binaries known. We also identify one system which shows very large ellipsoidal modulation (almost 0.3 mag), implying that the system is both very close to Roche lobe overflow and at high inclination. However, our follow-up photometry failed to firmly detect an eclipse, meaning that either this system contains a cool white dwarf and hence the eclipse is very shallow and undetectable in our red-sensitive photometry or that it is non-eclipsing. Radial velocity measurements for the main-sequence stars in three of our newly identified eclipsing systems imply that their white dwarf masses are lower than those inferred from modelling their SDSS spectra. 13 non-eclipsing post-common envelope binaries were also identified, from either reflection or ellipsoidal modulation effects. The white dwarfs in our newly discovered eclipsing systems span a wide range of parameters, including low-mass (˜0.3 M⊙), very hot (80 000 K) and a DC white dwarf. The spectral types of the main-sequence stars range from M2 to M6. This makes our sample ideal for testing white dwarf and low-mass star mass-radius relationships as well as close binary evolution.

  8. Experience with parametric binary dissection

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.

    1993-01-01

    Parametric Binary Dissection (PBD) is a new algorithm that can be used for partitioning graphs embedded in 2- or 3-dimensional space. It partitions explicitly on the basis of nodes + (lambda)x(edges cut), where lambda is the ratio of time to communicate over an edge to the time to compute at a node. The new algorithm is faster than the original binary dissection algorithm and attempts to obtain better partitions than the older algorithm, which only takes nodes into account. The performance of parametric dissection with plain binary dissection on 3 large unstructured 3-d meshes obtained from computational fluid dynamics and on 2 random graphs were compared. It was showm that the new algorithm can usually yield partitions that are substantially superior, but that its performance is heavily dependent on the input data.

  9. Close Encounters of the Stellar Kind

    NASA Astrophysics Data System (ADS)

    2003-07-01

    NASA's Chandra X-ray Observatory has confirmed that close encounters between stars form X-ray emitting, double-star systems in dense globular star clusters. These X-ray binaries have a different birth process than their cousins outside globular clusters, and should have a profound influence on the cluster's evolution. A team of scientists led by David Pooley of the Massachusetts Institute of Technology in Cambridge took advantage of Chandra's unique ability to precisely locate and resolve individual sources to determine the number of X-ray sources in 12 globular clusters in our Galaxy. Most of the sources are binary systems containing a collapsed star such as a neutron star or a white dwarf star that is pulling matter off a normal, Sun-like companion star. "We found that the number of X-ray binaries is closely correlated with the rate of encounters between stars in the clusters," said Pooley. "Our conclusion is that the binaries are formed as a consequence of these encounters. It is a case of nurture not nature." A similar study led by Craig Heinke of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. confirmed this conclusion, and showed that roughly 10 percent of these X-ray binary systems contain neutron stars. Most of these neutron stars are usually quiet, spending less than 10% of their time actively feeding from their companion. NGC 7099 NGC 7099 A globular cluster is a spherical collection of hundreds of thousands or even millions of stars buzzing around each other in a gravitationally-bound stellar beehive that is about a hundred light years in diameter. The stars in a globular cluster are often only about a tenth of a light year apart. For comparison, the nearest star to the Sun, Proxima Centauri, is 4.2 light years away. With so many stars moving so close together, interactions between stars occur frequently in globular clusters. The stars, while rarely colliding, do get close enough to form binary star systems or cause binary stars to

  10. Single-spin precessing gravitational waveform in closed form

    NASA Astrophysics Data System (ADS)

    Lundgren, Andrew; O'Shaughnessy, R.

    2014-02-01

    In coming years, gravitational-wave detectors should find black hole-neutron star (BH-NS) binaries, potentially coincident with astronomical phenomena like short gamma ray bursts. These binaries are expected to precess. Gravitational-wave science requires a tractable model for precessing binaries, to disentangle precession physics from other phenomena like modified strong field gravity, tidal deformability, or Hubble flow; and to measure compact object masses, spins, and alignments. Moreover, current searches for gravitational waves from compact binaries use templates where the binary does not precess and are ill-suited for detection of generic precessing sources. In this paper we provide a closed-form representation of the single-spin precessing waveform in the frequency domain by reorganizing the signal as a sum over harmonics, each of which resembles a nonprecessing waveform. This form enables simple analytic calculations of the Fisher matrix for use in template bank generation and coincidence metrics, and jump proposals to improve the efficiency of Markov chain Monte Carlo sampling. We have verified that for generic BH-NS binaries, our model agrees with the time-domain waveform to 2%. Straightforward extensions of the derivations outlined here (and provided in full online) allow higher accuracy and error estimates.

  11. Mental Effort in Binary Categorization Aided by Binary Cues

    ERIC Educational Resources Information Center

    Botzer, Assaf; Meyer, Joachim; Parmet, Yisrael

    2013-01-01

    Binary cueing systems assist in many tasks, often alerting people about potential hazards (such as alarms and alerts). We investigate whether cues, besides possibly improving decision accuracy, also affect the effort users invest in tasks and whether the required effort in tasks affects the responses to cues. We developed a novel experimental tool…

  12. BINARY YORP EFFECT AND EVOLUTION OF BINARY ASTEROIDS

    SciTech Connect

    Steinberg, Elad; Sari, Re'em

    2011-02-15

    The rotation states of kilometer-sized near-Earth asteroids are known to be affected by the Yarkevsky O'Keefe-Radzievskii-Paddack (YORP) effect. In a related effect, binary YORP (BYORP), the orbital properties of a binary asteroid evolve under a radiation effect mostly acting on a tidally locked secondary. The BYORP effect can alter the orbital elements over {approx}10{sup 4}-10{sup 5} years for a D{sub p} = 2 km primary with a D{sub s} = 0.4 km secondary at 1 AU. It can either separate the binary components or cause them to collide. In this paper, we devise a simple approach to calculate the YORP effect on asteroids and the BYORP effect on binaries including J{sub 2} effects due to primary oblateness and the Sun. We apply this to asteroids with known shapes as well as a set of randomly generated bodies with various degrees of smoothness. We find a strong correlation between the strengths of an asteroid's YORP and BYORP effects. Therefore, statistical knowledge of one could be used to estimate the effect of the other. We show that the action of BYORP preferentially shrinks rather than expands the binary orbit and that YORP preferentially slows down asteroids. This conclusion holds for the two extremes of thermal conductivities studied in this work and the assumption that the asteroid reaches a stable point, but may break down for moderate thermal conductivity. The YORP and BYORP effects are shown to be smaller than could be naively expected due to near cancellation of the effects at small scales. Taking this near cancellation into account, a simple order-of-magnitude estimate of the YORP and BYORP effects as a function of the sizes and smoothness of the bodies is calculated. Finally, we provide a simple proof showing that there is no secular effect due to absorption of radiation in BYORP.

  13. Observational Properties of Synthetic Visual Binary Catalog

    NASA Astrophysics Data System (ADS)

    Nurmi, P.

    2004-08-01

    Forthcoming astrometric missions will observe a huge number of new binaries from which a large fraction will be visual binaries. Detailed planning of optimal detection procedures requires pre-launch information about the observational properties of expected visual binaries. Hence, a synthetic binary catalog is created and analyzed for observational properties of visual binary stars. These results help to understand what kind of binaries we expect to find in the final output catalogs of astrometric missions. These results represent `true' binary distributions if all of them would be observed. All real observational projects or astrometric satellites sample only small fractions of these populations depending on the observational capabilities of the missions. In this study we consider only relative numbers with respect to the total number of binary stars assumed to exist in the sky down to the magnitude limit depending on the astrometric mission.

  14. Critically-rotating Stars in Binaries-An Unsolved Problem

    NASA Astrophysics Data System (ADS)

    de Mink, S. E.; Pols, O. R.; Glebbeek, E.

    2007-11-01

    In close binaries mass and angular momentum can be transferred from one star to the other during Roche-lobe overflow. The efficiency of this process is not well understood and constitutes one of the largest uncertainties in binary evolution. One of the problems lies in the transfer of angular momentum, which will spin up the accreting star. In very tight systems tidal friction can prevent reaching critical rotation, by locking the spin period to the orbital period. Accreting stars in systems with orbital periods larger than a few days reach critical rotation after accreting only a fraction of their mass, unless there is an effective mechanism to get rid of angular momentum. In low-mass stars magnetic field might help. In more-massive stars angular-momentum loss will be accompanied by strong mass loss. This would imply that most interacting binaries with initial orbital periods larger than a few days evolve very non-conservatively. In this contribution we wish to draw attention to the unsolved problems related to mass and angular-momentum transfer in binary systems. We do this by presenting the first results of an implementation of spin up by accretion into the TWIN version of the Eggleton stellar-evolution code.

  15. A spectroscopic binary in the Hercules dwarf spheroidal galaxy

    SciTech Connect

    Koch, Andreas; Hansen, Terese; Feltzing, Sofia; Wilkinson, Mark I.

    2014-01-01

    We present the radial velocity curve of a single-lined spectroscopic binary in the faint Hercules dwarf spheroidal (dSph) galaxy, based on 34 individual spectra covering more than 2 yr of observations. This is the first time that orbital elements could be derived for a binary in a dSph. The system consists of a metal-poor red giant and a low-mass companion, possibly a white dwarf, with a 135 day period in a moderately eccentric (e = 0.18) orbit. Its period and eccentricity are fully consistent with metal-poor binaries in the Galactic halo, while the projected semimajor axis is small, at a{sub p} sin i = 38 R {sub ☉}. In fact, a very close orbit could inhibit the production of heavier elements through s-process nucleosynthesis, leading to the very low abundances of neutron-capture elements that are found in this star. We discuss the further implications for the chemical enrichment history of the Hercules dSph, but find no compelling binary scenario that could reasonably explain the full, peculiar abundance pattern of the Hercules dSph galaxy.

  16. Secular dynamics of gravitationally bound pair of binaries

    NASA Astrophysics Data System (ADS)

    Vokrouhlický, David

    2016-10-01

    Equations of secular dynamics for stellar quadruple systems in 2+2 hierarchy are formulated. Non-singular, angular momentum and Laplace vector variables are used to describe orbital evolution of both inner and outer orbits. Given a typical wide separation of the binaries in these systems, gravitational interactions are truncated at the octupole approximation. Secular equations are propagated numerically and the results compared to the complete numerical integration on a long time-scale. Our basic formulation uses a point-mass model, but we also extend it by including the simplest description of the quadrupole interaction among the components of close (inner) binaries. Evolution of orbital planes of the binaries is discussed analytically in a simplified model and numerically using a more complete model. Maximum angular separation of the two orbital planes reaches only 20-40 per cent of the simple geometric maximum value for low-eccentricity cases with small inclination with respect to the orbital plane of the relative motion. This may be a pre-requisite for occurrence of quadruple systems with both binaries showing eclipses. However, statistical occurrence of eclipses at any time for a synthetic population of quadruples with initially isotropic distribution of orbital planes is about equal to the model where the orbits do not evolve due to gravitational interactions. We also show that the model is potentially suitable for long-term studies of the initial evolutionary tracks of the 2 + 2 quadruple systems.

  17. Origin of apparent period variations in eclipsing post-common-envelope binaries

    NASA Astrophysics Data System (ADS)

    Zorotovic, M.; Schreiber, M. R.

    2013-01-01

    Context. Apparent period variations detected in several eclipsing, close-compact binaries are frequently interpreted as being caused by circumbinary giant planets. This interpretation raises the question of the origin of the potential planets that must have either formed in the primordial circumbinary disk, together with the host binary star, and survived its evolution into a close-compact binary or formed in a post-common-envelope circumbinary disk that remained bound to the post-common-envelope binary (PCEB). Aims: Here we combine current knowledge of planet formation and the statistics of giant planets around primordial and evolved binary stars with the theory of close-compact binary star evolution aiming to derive new constraints on possible formation scenarios. Methods: We compiled a comprehensive list of observed eclipsing PCEBs, estimated the fraction of systems showing apparent period variations, reconstructed the evolutionary history of the PCEBs, and performed binary population models of PCEBs to characterize their main sequence binary progenitors. We reviewed the currently available constraints on the fraction of PCEB progenitors that host circumbinary giant planets. Results: We find that the progenitors of PCEBs are very unlikely to be frequent hosts of giant planets (≲10 per cent), while the frequency of PCEBs with observed apparent period variations is very high (~90 per cent). Conclusions: The variations in eclipse timings measured in eclipsing PCEBs are probably not caused by first-generation planets that survived common-envelope evolution. The remaining options for explaining the observed period variations are second-generation planet formation or perhaps variations in the shape of a magnetically active secondary star. We suggest observational tests for both options. Appendix A is available in electronic form at http://www.aanda.org

  18. A Galactic Binary Detection Pipeline

    NASA Technical Reports Server (NTRS)

    Littenberg, Tyson B.

    2011-01-01

    The Galaxy is suspected to contain hundreds of millions of binary white dwarf systems, a large fraction of which will have sufficiently small orbital period to emit gravitational radiation in band for space-based gravitational wave detectors such as the Laser Interferometer Space Antenna (LISA). LISA's main science goal is the detection of cosmological events (supermassive black hole mergers, etc.) however the gravitational signal from the galaxy will be the dominant contribution to the data - including instrumental noise over approximately two decades in frequency. The catalogue of detectable binary systems will serve as an unparalleled means of studying the Galaxy. Furthermore, to maximize the scientific return from the mission, the data must be "cleansed" of the galactic foreground. We will present an algorithm that can accurately resolve and subtract 2:: 10000 of these sources from simulated data supplied by the Mock LISA Data Challenge Task Force. Using the time evolution of the gravitational wave frequency, we will reconstruct the position of the recovered binaries and show how LISA will sample the entire compact binary population in the Galaxy.

  19. Spectral Investigation of Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Birlan, Mirel; Nedelcu, D.; Descamps, P.; Berthier, J.; Marchis, F.; Merouane, S.

    2008-09-01

    The number of binary asteroids increased in a significant manner during the last years. Multiple types of observations obtained in adaptive optics, photometry, and radar, allow the rethinking not only the dynamics of the asteroids, but also their physics. The spectroscopy of a binary system can play a key role for establish the mineralogical composition of components, and implicitly the range of their density. By the application of these considerations to the physical and dynamical models, the physical parameters such as the macro-porosity or the "rubble pile” structures could be derived. Observations of binary asteroid (854) Frostia, and binary candidates (1333) Cevenola, and (3632) Chaplin were carried out in the 0.8-2.5 µm spectral range using SpeX/IRTF in LowRes mode. The asteroids present features in both 1 and 2 µm regions, suggesting the presence of silicates in the surface composition. The analysis of slopes, band strengths, and the most probable mineralogical models will be presented.

  20. Discs in misaligned binary systems

    NASA Astrophysics Data System (ADS)

    Rawiraswattana, Krisada; Hubber, David A.; Goodwin, Simon P.

    2016-08-01

    We perform SPH simulations to study precession and changes in alignment between the circumprimary disc and the binary orbit in misaligned binary systems. We find that the precession process can be described by the rigid-disc approximation, where the disc is considered as a rigid body interacting with the binary companion only gravitationally. Precession also causes change in alignment between the rotational axis of the disc and the spin axis of the primary star. This type of alignment is of great important for explaining the origin of spin-orbit misaligned planetary systems. However, we find that the rigid-disc approximation fails to describe changes in alignment between the disc and the binary orbit. This is because the alignment process is a consequence of interactions that involve the fluidity of the disc, such as the tidal interaction and the encounter interaction. Furthermore, simulation results show that there are not only alignment processes, which bring the components towards alignment, but also anti-alignment processes, which tend to misalign the components. The alignment process dominates in systems with misalignment angle near 90°, while the anti-alignment process dominates in systems with the misalignment angle near 0° or 180°. This means that highly misaligned systems will become more aligned but slightly misaligned systems will become more misaligned.

  1. Generating Constant Weight Binary Codes

    ERIC Educational Resources Information Center

    Knight, D.G.

    2008-01-01

    The determination of bounds for A(n, d, w), the maximum possible number of binary vectors of length n, weight w, and pairwise Hamming distance no less than d, is a classic problem in coding theory. Such sets of vectors have many applications. A description is given of how the problem can be used in a first-year undergraduate computational…

  2. Binary Central Stars of Planetary Nebulae Discovered through Photometric Variability. IV. The Central Stars of HaTr 4 and Hf 2-2

    NASA Astrophysics Data System (ADS)

    Hillwig, Todd C.; Bond, Howard E.; Frew, David J.; Schaub, S. C.; Bodman, Eva H. L.

    2016-08-01

    We explore the photometrically variable central stars of the planetary nebulae HaTr 4 and Hf 2-2. Both have been classified as close binary star systems previously based on their light curves alone. Here, we present additional arguments and data confirming the identification of both as close binaries with an irradiated cool companion to the hot central star. We include updated light curves, orbital periods, and preliminary binary modeling for both systems. We also identify for the first time the central star of HaTr 4 as an eclipsing binary. Neither system has been well studied in the past, but we utilize the small amount of existing data to limit possible binary parameters, including system inclination. These parameters are then compared to nebular parameters to further our knowledge of the relationship between binary central stars of planetary nebulae and nebular shaping and ejection.

  3. A Speeding Binary in the Galactic Halo

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-04-01

    The recent discovery of a hyper-velocity binary star system in the halo of the Milky Way poses a mystery: how was this system accelerated to its high speed?Accelerating StarsUnlike the uniform motion in the Galactic disk, stars in the Milky Ways halo exhibit a huge diversity of orbits that are usually tilted relative to the disk and have a variety of speeds. One type of halo star, so-called hyper-velocity stars, travel with speeds that can approach the escape velocity of the Galaxy.How do these hyper-velocity stars come about? Assuming they form in the Galactic disk, there are multiple proposed scenarios through which they could be accelerated and injected into the halo, such as:Ejection after a close encounter with the supermassive black hole at the Galactic centerEjection due to a nearby supernova explosionEjection as the result of a dynamical interaction in a dense stellar population.Further observations of hyper-velocity stars are necessary to identify the mechanism responsible for their acceleration.J1211s SurpriseModels of J1211s orbit show it did not originate from the Galactic center (black dot). The solar symbol shows the position of the Sun and the star shows the current position of J1211. The bottom two panels show two depictions(x-y plane and r-z plane) of estimated orbits of J1211 over the past 10 Gyr. [Nmeth et al. 2016]To this end, a team of scientists led by Pter Nmeth (Friedrich Alexander University, Erlangen-Nrnberg) recently studied the candidate halo hyper-velocity star SDSS J121150.27+143716.2. The scientists obtained spectroscopy of J1211 using spectrographs at the Keck Telescope in Hawaii and ESOs Very Large Telescope in Chile. To their surprise, they discovered the signature of a companion in the spectra: J1211 is actually a binary!Nmeth and collaborators found that J1211, located roughly 18,000 light-years away, is moving at a rapid ~570 km/s relative to the galactic rest frame. The binary system consists of a hot (30,600 K) subdwarf and a

  4. Rotational breakup as the origin of small binary asteroids.

    PubMed

    Walsh, Kevin J; Richardson, Derek C; Michel, Patrick

    2008-07-10

    Asteroids with satellites are observed throughout the Solar System, from subkilometre near-Earth asteroid pairs to systems of large and distant bodies in the Kuiper belt. The smallest and closest systems are found among the near-Earth and small inner main-belt asteroids, which typically have rapidly rotating primaries and close secondaries on circular orbits. About 15 per cent of near-Earth and main-belt asteroids with diameters under 10 km have satellites. The mechanism that forms such similar binaries in these two dynamically different populations was hitherto unclear. Here we show that these binaries are created by the slow spinup of a 'rubble pile' asteroid by means of the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect. We find that mass shed from the equator of a critically spinning body accretes into a satellite if the material is collisionally dissipative and the primary maintains a low equatorial elongation. The satellite forms mostly from material originating near the primary's surface and enters into a close, low-eccentricity orbit. The properties of binaries produced by our model match those currently observed in the small near-Earth and main-belt asteroid populations, including 1999 KW(4) (refs 3, 4).

  5. Rotational breakup as the origin of small binary asteroids.

    PubMed

    Walsh, Kevin J; Richardson, Derek C; Michel, Patrick

    2008-07-10

    Asteroids with satellites are observed throughout the Solar System, from subkilometre near-Earth asteroid pairs to systems of large and distant bodies in the Kuiper belt. The smallest and closest systems are found among the near-Earth and small inner main-belt asteroids, which typically have rapidly rotating primaries and close secondaries on circular orbits. About 15 per cent of near-Earth and main-belt asteroids with diameters under 10 km have satellites. The mechanism that forms such similar binaries in these two dynamically different populations was hitherto unclear. Here we show that these binaries are created by the slow spinup of a 'rubble pile' asteroid by means of the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect. We find that mass shed from the equator of a critically spinning body accretes into a satellite if the material is collisionally dissipative and the primary maintains a low equatorial elongation. The satellite forms mostly from material originating near the primary's surface and enters into a close, low-eccentricity orbit. The properties of binaries produced by our model match those currently observed in the small near-Earth and main-belt asteroid populations, including 1999 KW(4) (refs 3, 4). PMID:18615078

  6. Neutron star high-mass binaries as the origin of SGR/AXP

    NASA Astrophysics Data System (ADS)

    Wang, J.

    2016-03-01

    A close high-mass binary system consisting of a neutron star (NS) and a massive OB supergiant companion is expected to lead to a Thorne-Żytkow object (TZO) structure, which consists of a NS core and a stellar envelope. We use the scenario machine program to calculate the formation tracks of TZOs in close high-mass NS binaries and their subsequent evolution. We propose and demonstrate that the explosion and instant contraction of a TZO structure leave its stellar remnant as a soft gamma-ray repeater and an anomalous X-ray pulsar respectively.

  7. School Closings in Philadelphia

    ERIC Educational Resources Information Center

    Jack, James; Sludden, John

    2013-01-01

    In 2012, the School District of Philadelphia closed six schools. In 2013, it closed 24. The closure of 30 schools has occurred amid a financial crisis, headlined by the district's $1.35 billion deficit. School closures are one piece of the district's plan to cut expenditures and close its budget gap. The closures are also intended to…

  8. Formation of the widest binary stars from dynamical unfolding of triple systems.

    PubMed

    Reipurth, Bo; Mikkola, Seppo

    2012-12-13

    The formation of very wide binary systems, such as the α Centauri system with Proxima (also known as α Centauri C) separated from α Centauri (which itself is a close binary A/B) by 15,000 astronomical units (1 AU is the distance from Earth to the Sun), challenges current theories of star formation, because their separation can exceed the typical size of a collapsing cloud core. Various hypotheses have been proposed to overcome this problem, including the suggestion that ultrawide binaries result from the dissolution of a star cluster--when a cluster star gravitationally captures another, distant, cluster star. Recent observations have shown that very wide binaries are frequently members of triple systems and that close binaries often have a distant third companion. Here we report N-body simulations of the dynamical evolution of newborn triple systems still embedded in their nascent cloud cores that match observations of very wide systems. We find that although the triple systems are born very compact--and therefore initially are more protected against disruption by passing stars--they can develop extreme hierarchical architectures on timescales of millions of years as one component is dynamically scattered into a very distant orbit. The energy of ejection comes from shrinking the orbits of the other two stars, often making them look from a distance like a single star. Such loosely bound triple systems will therefore appear to be very wide binaries. PMID:23222523

  9. Formation of the widest binary stars from dynamical unfolding of triple systems.

    PubMed

    Reipurth, Bo; Mikkola, Seppo

    2012-12-13

    The formation of very wide binary systems, such as the α Centauri system with Proxima (also known as α Centauri C) separated from α Centauri (which itself is a close binary A/B) by 15,000 astronomical units (1 AU is the distance from Earth to the Sun), challenges current theories of star formation, because their separation can exceed the typical size of a collapsing cloud core. Various hypotheses have been proposed to overcome this problem, including the suggestion that ultrawide binaries result from the dissolution of a star cluster--when a cluster star gravitationally captures another, distant, cluster star. Recent observations have shown that very wide binaries are frequently members of triple systems and that close binaries often have a distant third companion. Here we report N-body simulations of the dynamical evolution of newborn triple systems still embedded in their nascent cloud cores that match observations of very wide systems. We find that although the triple systems are born very compact--and therefore initially are more protected against disruption by passing stars--they can develop extreme hierarchical architectures on timescales of millions of years as one component is dynamically scattered into a very distant orbit. The energy of ejection comes from shrinking the orbits of the other two stars, often making them look from a distance like a single star. Such loosely bound triple systems will therefore appear to be very wide binaries.

  10. Formation of the widest binary stars from dynamical unfolding of triple systems

    NASA Astrophysics Data System (ADS)

    Reipurth, Bo; Mikkola, Seppo

    2012-12-01

    The formation of very wide binary systems, such as the α Centauri system with Proxima (also known as α Centauri C) separated from α Centauri (which itself is a close binary A/B) by 15,000 astronomical units (1 AU is the distance from Earth to the Sun), challenges current theories of star formation, because their separation can exceed the typical size of a collapsing cloud core. Various hypotheses have been proposed to overcome this problem, including the suggestion that ultrawide binaries result from the dissolution of a star cluster--when a cluster star gravitationally captures another, distant, cluster star. Recent observations have shown that very wide binaries are frequently members of triple systems and that close binaries often have a distant third companion. Here we report N-body simulations of the dynamical evolution of newborn triple systems still embedded in their nascent cloud cores that match observations of very wide systems. We find that although the triple systems are born very compact--and therefore initially are more protected against disruption by passing stars--they can develop extreme hierarchical architectures on timescales of millions of years as one component is dynamically scattered into a very distant orbit. The energy of ejection comes from shrinking the orbits of the other two stars, often making them look from a distance like a single star. Such loosely bound triple systems will therefore appear to be very wide binaries.

  11. Star cluster evolution with primordial binaries. 3: Effect of the Galactic tidal field

    NASA Technical Reports Server (NTRS)

    Mcmillan, Steve; Hut, Piet

    1994-01-01

    We present the results of N-body simulations of tidally limited star clusters with an initial population of 0%-20% binaries. We find that (1) if enough binaries are initially present, the binary fraction may fall to a minimum value, then increase at late times; (2) the cluster evaporation timescale is quite insensitive to the details of the initial binary distribution; (3) the cluster core radius stabilizes at a few percent of the half-mass radius when binaries are present, just as in the case of isolated clusters; and (4) there may be a marked difference between the spatial distribution of low-energy and high-energy binaries as the cluster evolves. Specifically, the spatial distribution of the lower energy systems is often substantially more extended than that of the more tightly bound pairs. At no time are our simulated clusters well described by simple dynamical models that neglect the close coupling between the binding energies and the center-of-mass energies of the binaries they contain.

  12. Prediction of binary hard-sphere crystal structures.

    PubMed

    Filion, Laura; Dijkstra, Marjolein

    2009-04-01

    We present a method based on a combination of a genetic algorithm and Monte Carlo simulations to predict close-packed crystal structures in hard-core systems. We employ this method to predict the binary crystal structures in a mixture of large and small hard spheres with various stoichiometries and diameter ratios between 0.4 and 0.84. In addition to known binary hard-sphere crystal structures similar to NaCl and AlB2, we predict additional crystal structures with the symmetry of CrB, gammaCuTi, alphaIrV, HgBr2, AuTe2, Ag2Se, and various structures for which an atomic analog was not found. In order to determine the crystal structures at infinite pressures, we calculate the maximum packing density as a function of size ratio for the crystal structures predicted by our GA using a simulated annealing approach. PMID:19518387

  13. On the structure of contact binaries. I - The contact discontinuity

    NASA Technical Reports Server (NTRS)

    Shu, F. H.; Lubow, S. H.; Anderson, L.

    1976-01-01

    The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified.

  14. SPECKLE INTERFEROMETRY AND ORBITS OF 'FAST' VISUAL BINARIES

    SciTech Connect

    Tokovinin, Andrei

    2012-08-15

    Results of speckle observations at the 4.1 m SOAR telescope in 2012 (158 measures of 121 systems, 27 non-resolutions) are reported. The aim is to follow fast orbital motion of recently discovered or neglected close binaries and sub-systems. Here, eight previously known orbits are defined better, two more are completely revised, and five orbits are computed for the first time. Using differential photometry from Hipparcos or speckle and the standard relation between mass and absolute magnitude, the component's masses and dynamical parallaxes are estimated for all 15 systems with new or updated orbits. Two astrometric binaries HIP 54214 and 56245 are resolved here for the first time, another eight are measured. We highlight several unresolved pairs that may actually be single despite multiple historic measures, such as 104 Tau and f Pup AB. Continued monitoring is needed to understand those enigmatic cases.

  15. Superluminal Jets and Other Properties of Black Holes Binaries

    NASA Technical Reports Server (NTRS)

    Harmon, Alan

    1997-01-01

    Discoveries in the past few years of radio jets in Galactic black hole candidates have provided a link between active galactic nuclei (AGNS) and the compact stars in binary systems. The availability of binary systems relatively close by is an opportunity to learn about the jet production mechanism on a timescale a million times shorter than that of an AGN. Evidence is clearly seen of correlated high energy X-ray and gamma ray emission to radio emission from jets, linking the accretion and jet production mechanisms. objects such as GRS 1915+105, GRO J1655-40 and Cyg X-3 show striking properties which distinguish them from other black hole candidates. Our theoretical understanding of these systems is still in the formative stages. I review some of the most recent multiwavelength data and point out questions raised by these observations.

  16. BINARIES DISCOVERED BY THE MUCHFUSS PROJECT: SDSS J08205+0008-AN ECLIPSING SUBDWARF B BINARY WITH A BROWN DWARF COMPANION

    SciTech Connect

    Geier, S.; Schaffenroth, V.; Drechsel, H.; Heber, U.; Kupfer, T.; Tillich, A.; Oestensen, R. H.; Smolders, K.; Degroote, P.; Maxted, P. F. L.; Barlow, B. N.; Gaensicke, B. T.; Marsh, T. R.; Napiwotzki, R.

    2011-04-20

    Hot subdwarf B stars (sdBs) are extreme horizontal branch stars believed to originate from close binary evolution. Indeed about half of the known sdB stars are found in close binaries with periods ranging from a few hours to a few days. The enormous mass loss required to remove the hydrogen envelope of the red-giant progenitor almost entirely can be explained by common envelope ejection. A rare subclass of these binaries are the eclipsing HW Vir binaries where the sdB is orbited by a dwarf M star. Here, we report the discovery of an HW Vir system in the course of the MUCHFUSS project. A most likely substellar object ({approx_equal}0.068 M{sub sun}) was found to orbit the hot subdwarf J08205+0008 with a period of 0.096 days. Since the eclipses are total, the system parameters are very well constrained. J08205+0008 has the lowest unambiguously measured companion mass yet found in a subdwarf B binary. This implies that the most likely substellar companion has not only survived the engulfment by the red-giant envelope, but also triggered its ejection and enabled the sdB star to form. The system provides evidence that brown dwarfs may indeed be able to significantly affect late stellar evolution.

  17. Feshbach Correlations and Closed Channel Amplitudes

    NASA Astrophysics Data System (ADS)

    Lopez, Nicolas; Tsai, Shan-Wen; Timmermans, Eddy

    2012-02-01

    The magnetically controlled Feshbach resonance is a prominent member of the cold atom toolkit. The ability to tune binary particle interactions in a quantum many body system has given access to collapsing BEC-physics in bosenovas, to BEC-BCS crossover physics, to the unitarity regime, and to quantum phase transitions. The resonance is accessed by tuning the energy of a quasi-bound spin-rearranged molecular state near the vaccuum of the interacting particles. Does the amplitude of the spin-rearranged or ``closed channel'' state play a significant role in the many body physics? We present a microscopic derivation of the Feshbach resonance interactions and obtain the parameters of the two-channel model in a optical lattice. We study two atoms interacting in a harmonic oscillator potential near a Feshbach resonance to derive the closed channel probabibilty and to uncover the validity-range of the two channel lattice model.

  18. Binary Stars in SBS Survey

    NASA Astrophysics Data System (ADS)

    Erastova, L. K.

    2016-06-01

    Thirty spectroscopic binary stars were found in the Second Byurakan Survey (SBS). They show composite spectra - WD(DA)+dM or dC (for example Liebert et al. 1994). They may have red color, if the radiation of the red star dominates, and blue one, if the blue star is brighter and have peculiar spectrum in our survey plate. We obtained slit spectra for most of such objects. But we often see the spectrum of one component, because our slit spectra did not cover all optical range. We examine by eye the slit spectra of all SBS stellar objects (˜700) in SDSS DR7, DR8 or DR9 independent on our observations. We confirmed or discovered the duplicity of 30 stars. Usually they are spectroscopic binaries, where one component is WD (DA) and the second one is a red star with or without emission. There also are other components combinations. Sometimes there are emission lines, probably, indicating variable ones.

  19. Desktop setup for binary holograms

    NASA Astrophysics Data System (ADS)

    Ginter, Olaf; Rothe, Hendrik

    1996-08-01

    Binary gratings as holograms itself or as photographic masking tools for further fabrication steps can fulfill a lot of applications. The commonly used semiconductor technologies for direct writing of high resolution structures are often too expensive. On the other hand computer plots at a reasonable price with photographic reduction do not meet the needs of precision e.g. for interferometric inspection. The lack of cheap and reliable instruments for direct writing in an appropriate resolution is still a problem in fabricating synthetic holograms. Using off-the-shelf components a direct writing plotter for binary patterns can be built at moderate costs. Typical design rules as well as experimental results are given and the final setup is introduced.

  20. Binary Inspiral in Quadratic Gravity

    NASA Astrophysics Data System (ADS)

    Yagi, Kent

    2015-01-01

    Quadratic gravity is a general class of quantum-gravity-inspired theories, where the Einstein-Hilbert action is extended through the addition of all terms quadratic in the curvature tensor coupled to a scalar field. In this article, we focus on the scalar Gauss- Bonnet (sGB) theory and consider the black hole binary inspiral in this theory. By applying the post-Newtonian (PN) formalism, we found that there is a scalar dipole radiation which leads to -1PN correction in the energy flux relative to gravitational radiation in general relativity. From the orbital decay rate of a low-mass X-ray binary A0600-20, we obtain the bound that is six orders of magnitude stronger than the current solar system bound. Furthermore, we show that the excess in the orbital decay rate of XTE J1118+480 can be explained by the scalar radiation in sGB theory.

  1. First Orbits for Five Binaries

    NASA Astrophysics Data System (ADS)

    Cvetković, Z.

    2008-10-01

    In this paper, new orbital elements are given for five binaries. For all of them—Washington Double Star (WDS) 00469+4339 = HDS 102, WDS 02186+4017 = EGG 2Aa, WDS 05542 - 2909 = FIN 382, WDS 06493- 0216 = FIN 322, and WDS 11495 - 4604 = FIN 366—the orbital elements are calculated for the first time. One of the five binaries, HDS 102, was discovered during the Hipparcos mission, whereas the remaining four were discovered between 1952 and 1965. All measured separations are less than 0farcs3 and most of the measures were done using the interferometric techniques. The orbital periods calculated are between 28 and 109 years. In addition to the orbital elements, the (O - C) residuals in θ and ρ, masses, dynamical parallaxes, absolute magnitudes, and ephemerides for the next five years are also given in this paper.

  2. Massive Binary Black Holes in the Cosmic Landscape

    NASA Astrophysics Data System (ADS)

    Colpi, Monica; Dotti, Massimo

    2011-02-01

    Binary black holes occupy a special place in our quest for understanding the evolution of galaxies along cosmic history. If massive black holes grow at the center of (pre-)galactic structures that experience a sequence of merger episodes, then dual black holes form as inescapable outcome of galaxy assembly, and can in principle be detected as powerful dual quasars. But, if the black holes reach coalescence, during their inspiral inside the galaxy remnant, then they become the loudest sources of gravitational waves ever in the universe. The Laser Interferometer Space Antenna is being developed to reveal these waves that carry information on the mass and spin of these binary black holes out to very large look-back times. Nature seems to provide a pathway for the formation of these exotic binaries, and a number of key questions need to be addressed: How do massive black holes pair in a merger? Depending on the properties of the underlying galaxies, do black holes always form a close Keplerian binary? If a binary forms, does hardening proceed down to the domain controlled by gravitational wave back reaction? What is the role played by gas and/or stars in braking the black holes, and on which timescale does coalescence occur? Can the black holes accrete on flight and shine during their pathway to coalescence? After outlining key observational facts on dual/binary black holes, we review the progress made in tracing their dynamics in the habitat of a gas-rich merger down to the smallest scales ever probed with the help of powerful numerical simulations. N-Body/hydrodynamical codes have proven to be vital tools for studying their evolution, and progress in this field is expected to grow rapidly in the effort to describe, in full realism, the physics of stars and gas around the black holes, starting from the cosmological large scale of a merger. If detected in the new window provided by the upcoming gravitational wave experiments, binary black holes will provide a deep view

  3. Cool Star Binaries with ALEXIS

    NASA Technical Reports Server (NTRS)

    Stern, Robert A.

    1998-01-01

    We proposed to search for high-temperature, flare-produced Fe XXIII line emission from active cool star binary systems using the ALEXIS all-sky survey. Previous X-ray transient searches with ARIEL V and HEAO-1, and subsequent shorter duration monitoring with the GINGA and EXOSAT satellites demonstrated that active binaries can produce large (EM approximately equals 10(exp 55-56/cu cm) X-ray flares lasting several hours or longer. Hot plasma from these flares at temperatures of 10(exp 7)K or more should produce Fe XXIII line emission at lambda = 132.8 A, very near the peak response of ALEXIS telescopes 1A and 2A. Our primary goals were to estimate flare frequency for the largest flares in the active binary systems, and, if the data permitted, to derive a distribution of flare energy vs. frequency for the sample as a whole. After a long delay due to the initial problems with the ALEXIS attitude control, the heroic efforts on the part of the ALEXIS satellite team enabled us to carry out this survey. However, the combination of the higher than expected and variable background in the ALEXIS detectors, and the lower throughput of the ALEXIS telescopes resulted in no convincing detections of large flares from the active binary systems. In addition, vignetting-corrected effective exposure times from the ALEXIS aspect solution were not available prior to the end of this contract; therefore, we were unable to convert upper limits measured in ALEXIS counts to the equivalent L(sub EUV).

  4. The Eclipsing Binary MY Cygni

    NASA Astrophysics Data System (ADS)

    Tucker, Rebecca; Sowell, J. R.; Williamon, R. M.

    2006-12-01

    Differential UBV photoelectric photometry for the eclipsing binary MY Cyg is presented. The Wilson-Devinney program is used to solve simultaneously the three light curves together with previously published radial velocities. We determine absolute dimensions and estimate the age of the system. We compute color indices for the two stars and estimate color excesses. A comparison is made with the previous solution found with the Russell-Merrill method.

  5. BINARY QUASARS AT HIGH REDSHIFT. I. 24 NEW QUASAR PAIRS AT z {approx} 3-4

    SciTech Connect

    Hennawi, Joseph F.; Myers, Adam D.; Shen, Yue; Strauss, Michael A.; Djorgovski, S. G.; Glikman, Eilat; Mahabal, Ashish; Fan Xiaohui; Martin, Crystal L.; Richards, Gordon T.; Schneider, Donald P.; Shankar, Francesco

    2010-08-20

    The clustering of quasars on small scales yields fundamental constraints on models of quasar evolution and the buildup of supermassive black holes. This paper describes the first systematic survey to discover high-redshift binary quasars. Using color-selection and photometric redshift techniques, we searched 8142 deg{sup 2} of Sloan Digital Sky Survey imaging data for binary quasar candidates, and confirmed them with follow-up spectroscopy. Our sample of 27 high-redshift binaries (24 of them new discoveries) at redshifts 2.9 < z < 4.3 with proper transverse separations 10 kpc < R{sub perpendicular} < 650 kpc increases the number of such objects known by an order of magnitude. Eight members of this sample are very close pairs with R{sub perpendicular} < 100 kpc, and of these close systems four are at z>3.5. The completeness and efficiency of our well-defined selection algorithm are quantified using simulated photometry and we find that our sample is {approx}50% complete. Our companion paper uses this knowledge to make the first measurement of the small-scale clustering (R < 1 h {sup -1} Mpc comoving) of high-redshift quasars. High-redshift binaries constitute exponentially rare coincidences of two extreme (M {approx}> 10{sup 9} M {sub sun}) supermassive black holes. At z {approx} 4, there is about one close binary per 10 Gpc{sup 3}, thus these could be the highest sigma peaks, the analogs of superclusters, in the early universe.

  6. Radial velocity curves of ellipsoidal red giant binaries in the Large Magellanic Cloud

    SciTech Connect

    Nie, J. D.; Wood, P. R. E-mail: peter.wood@anu.edu.au

    2014-12-01

    Ellipsoidal red giant binaries are close binary systems where an unseen, relatively close companion distorts the red giant, leading to light variations as the red giant moves around its orbit. These binaries are likely to be the immediate evolutionary precursors of close binary planetary nebula and post-asymptotic giant branch and post-red giant branch stars. Due to the MACHO and OGLE photometric monitoring projects, the light variability nature of these ellipsoidal variables has been well studied. However, due to the lack of radial velocity curves, the nature of their masses, separations, and other orbital details has so far remained largely unknown. In order to improve this situation, we have carried out spectral monitoring observations of a large sample of 80 ellipsoidal variables in the Large Magellanic Cloud and we have derived radial velocity curves. At least 12 radial velocity points with good quality were obtained for most of the ellipsoidal variables. The radial velocity data are provided with this paper. Combining the photometric and radial velocity data, we present some statistical results related to the binary properties of these ellipsoidal variables.

  7. Binary stars in loose associations

    NASA Astrophysics Data System (ADS)

    Azulay, R.; Guirado, J. C.; Marcaide, J. M.; Martí-Vidal, I.

    2013-05-01

    Precise determinations of dynamical masses of pre-main-sequence (PMS) stars are necessary to calibrate PMS stellar evolutionary models, whose predictions are in disagreement with measurements for masses below 1.2 M_{⊙}. Binary stars in young, nearby loose associations (moving groups) are particularly good candidates, primarily because all members share a common age. Belonging to the AB Doradus moving group, we have observed the binary AB Dor Ba/Bb, 0.06" separation, with the Australian Long Baseline Array at 8.4 GHz. We have detected the two components Ba/Bb, which facilitates (i) a measurement of the relative orbital motion through subsequent radio maps, and (ii) an estimate of the orbital parameters, once combined the radio information with infrared relative astrometry. Our preliminary analysis shows that best-fit orbit corresponds to that with a period of 1.1 yr and semi major axis of 0.068". The sum of the masses AB Dor Ba/Bb is 0.3±0.1 M_{⊙}. The study of this binary, along with other stars of the same association, will constitute a benchmark for testing PMS models of low-mass stars.

  8. The Long-Period Binary Frequency of the M67 Blue Stragglers and Binary-Binary Collisions

    NASA Astrophysics Data System (ADS)

    Leonard, P. J. T.

    1993-12-01

    The old open cluster M67 contains a dozen blue stragglers (BSs), one of which is a short-period spectroscopic binary, and thus is likely the result of binary mass transfer. A clue to the origin of the other BSs may be the fact that (>_ ~ ) 50% of them appear to be members of long-period (>10(3) days) binary systems (Milone et al. 1991, ASP Conference Series, 13, 424). If the majority of the M67 BSs are due to the slow coalescence of isolated binaries (Mateo et al. 1990, AJ, 100, 469), then there are two possible explanations for their anomalously high long-period binary frequency: 1) the frequency of triple star systems in M67 was initially similar to the binary frequency, and the inner components of some of these triple systems have merged to form BSs, or 2) the typical massive star in the core of M67 has suffered an exchange interaction with a binary star. The former solution requires a triple frequency that is vastly higher than in any other stellar population, and thus appears unlikely. The latter requires a rate of interactions involving binary stars in M67 so high that at least some of the BSs in the cluster must be the result of physical stellar collisions during binary-binary interactions. Consequently, one cannot accept the slow binary coalescence scenario for the M67 BSs without accepting that at least some of the M67 BSs have been produced via physical stellar collisions. Of course, the high long-period binary frequency of the M67 BSs can be naturally accounted for by the collisional hypothesis, since the majority of the merged stars produced by binary-binary collisions are expected to possess such companions (Leonard & Fahlman 1991, AJ, 102, 994; Leonard & Linnell 1992, AJ, 103, 1928). The high binary frequency observed in M67 (e.g., Montgomery et al. 1993, AJ, 106, 181) makes binary-binary interactions inevitable, and thus the collisional hypothesis appears to be quite a realistic possibility.

  9. GALAXY ROTATION AND RAPID SUPERMASSIVE BINARY COALESCENCE

    SciTech Connect

    Holley-Bockelmann, Kelly; Khan, Fazeel Mahmood

    2015-09-10

    Galaxy mergers usher the supermassive black hole (SMBH) in each galaxy to the center of the potential, where they form an SMBH binary. The binary orbit shrinks by ejecting stars via three-body scattering, but ample work has shown that in spherical galaxy models, the binary separation stalls after ejecting all the stars in its loss cone—this is the well-known final parsec problem. However, it has been shown that SMBH binaries in non-spherical galactic nuclei harden at a nearly constant rate until reaching the gravitational wave regime. Here we use a suite of direct N-body simulations to follow SMBH binary evolution in both corotating and counterrotating flattened galaxy models. For N > 500 K, we find that the evolution of the SMBH binary is convergent and is independent of the particle number. Rotation in general increases the hardening rate of SMBH binaries even more effectively than galaxy geometry alone. SMBH binary hardening rates are similar for co- and counterrotating galaxies. In the corotating case, the center of mass of the SMBH binary settles into an orbit that is in corotation resonance with the background rotating model, and the coalescence time is roughly a few 100 Myr faster than a non-rotating flattened model. We find that counterrotation drives SMBHs to coalesce on a nearly radial orbit promptly after forming a hard binary. We discuss the implications for gravitational wave astronomy, hypervelocity star production, and the effect on the structure of the host galaxy.

  10. Pulsed Accretion onto Eccentric and Circular Binaries

    NASA Astrophysics Data System (ADS)

    Muñoz, Diego J.; Lai, Dong

    2016-08-01

    We present numerical simulations of circumbinary accretion onto eccentric and circular binaries using the moving-mesh code AREPO. This is the first set of simulations to tackle the problem of binary accretion using a finite-volume scheme on a freely moving mesh, which allows for accurate measurements of accretion onto individual stars for arbitrary binary eccentricity. While accretion onto a circular binary shows bursts with period of ˜ 5 times the binary period P b, accretion onto an eccentric binary is predominantly modulated at the period ˜ 1{P}{{b}}. For an equal-mass circular binary, the accretion rates onto individual stars are quite similar to each other, following the same variable pattern in time. By contrast, for eccentric binaries, one of the stars can accrete at a rate 10–20 times larger than its companion. This “symmetry breaking” between the stars, however, alternates over timescales of order 200P b and can be attributed to a slowly precessing, eccentric circumbinary disk. Over longer timescales, the net accretion rates onto individual stars are the same, reaching a quasi-steady state with the circumbinary disk. These results have important implications for the accretion behavior of binary T Tauri stars and supermassive binary black holes.

  11. Pulsed Accretion onto Eccentric and Circular Binaries

    NASA Astrophysics Data System (ADS)

    Muñoz, Diego J.; Lai, Dong

    2016-08-01

    We present numerical simulations of circumbinary accretion onto eccentric and circular binaries using the moving-mesh code AREPO. This is the first set of simulations to tackle the problem of binary accretion using a finite-volume scheme on a freely moving mesh, which allows for accurate measurements of accretion onto individual stars for arbitrary binary eccentricity. While accretion onto a circular binary shows bursts with period of ˜ 5 times the binary period P b, accretion onto an eccentric binary is predominantly modulated at the period ˜ 1{P}{{b}}. For an equal-mass circular binary, the accretion rates onto individual stars are quite similar to each other, following the same variable pattern in time. By contrast, for eccentric binaries, one of the stars can accrete at a rate 10-20 times larger than its companion. This “symmetry breaking” between the stars, however, alternates over timescales of order 200P b and can be attributed to a slowly precessing, eccentric circumbinary disk. Over longer timescales, the net accretion rates onto individual stars are the same, reaching a quasi-steady state with the circumbinary disk. These results have important implications for the accretion behavior of binary T Tauri stars and supermassive binary black holes.

  12. Galaxy Rotation and Rapid Supermassive Binary Coalescence

    NASA Astrophysics Data System (ADS)

    Holley-Bockelmann, Kelly; Khan, Fazeel Mahmood

    2015-09-01

    Galaxy mergers usher the supermassive black hole (SMBH) in each galaxy to the center of the potential, where they form an SMBH binary. The binary orbit shrinks by ejecting stars via three-body scattering, but ample work has shown that in spherical galaxy models, the binary separation stalls after ejecting all the stars in its loss cone—this is the well-known final parsec problem. However, it has been shown that SMBH binaries in non-spherical galactic nuclei harden at a nearly constant rate until reaching the gravitational wave regime. Here we use a suite of direct N-body simulations to follow SMBH binary evolution in both corotating and counterrotating flattened galaxy models. For N > 500 K, we find that the evolution of the SMBH binary is convergent and is independent of the particle number. Rotation in general increases the hardening rate of SMBH binaries even more effectively than galaxy geometry alone. SMBH binary hardening rates are similar for co- and counterrotating galaxies. In the corotating case, the center of mass of the SMBH binary settles into an orbit that is in corotation resonance with the background rotating model, and the coalescence time is roughly a few 100 Myr faster than a non-rotating flattened model. We find that counterrotation drives SMBHs to coalesce on a nearly radial orbit promptly after forming a hard binary. We discuss the implications for gravitational wave astronomy, hypervelocity star production, and the effect on the structure of the host galaxy.

  13. Extrasolar binary planets. I. Formation by tidal capture during planet-planet scattering

    SciTech Connect

    Ochiai, H.; Nagasawa, M.; Ida, S.

    2014-08-01

    We have investigated (1) the formation of gravitationally bounded pairs of gas-giant planets (which we call 'binary planets') from capturing each other through planet-planet dynamical tide during their close encounters and (2) the subsequent long-term orbital evolution due to planet-planet and planet-star quasi-static tides. For the initial evolution in phase 1, we carried out N-body simulations of the systems consisting of three Jupiter-mass planets taking into account the dynamical tide. The formation rate of the binary planets is as much as 10% of the systems that undergo orbital crossing, and this fraction is almost independent of the initial stellarcentric semimajor axes of the planets, while ejection and merging rates sensitively depend on the semimajor axes. As a result of circularization by the planet-planet dynamical tide, typical binary separations are a few times the sum of the physical radii of the planets. After the orbital circularization, the evolution of the binary system is governed by long-term quasi-static tide. We analytically calculated the quasi-static tidal evolution in phase 2. The binary planets first enter the spin-orbit synchronous state by the planet-planet tide. The planet-star tide removes angular momentum of the binary motion, eventually resulting in a collision between the planets. However, we found that the binary planets survive the tidal decay for the main-sequence lifetime of solar-type stars (∼10 Gyr), if the binary planets are beyond ∼0.3 AU from the central stars. These results suggest that the binary planets can be detected by transit observations at ≳ 0.3 AU.

  14. Young and Waltzing Binary Stars

    NASA Astrophysics Data System (ADS)

    2001-10-01

    ADONIS Observes Low-mass Eclipsing System in Orion Summary A series of very detailed images of a binary system of two young stars have been combined into a movie . In merely 3 days, the stars swing around each other. As seen from the earth, they pass in front of each other twice during a full revolution, producing eclipses during which their combined brightness diminishes . A careful analysis of the orbital motions has now made it possible to deduce the masses of the two dancing stars . Both turn out to be about as heavy as our Sun. But while the Sun is about 4500 million years old, these two stars are still in their infancy. They are located some 1500 light-years away in the Orion star-forming region and they probably formed just 10 million years ago . This is the first time such an accurate determination of the stellar masses could be achieved for a young binary system of low-mass stars . The new result provides an important piece of information for our current understanding of how young stars evolve. The observations were obtained by a team of astronomers from Italy and ESO [1] using the ADaptive Optics Near Infrared System (ADONIS) on the 3.6-m telescope at the ESO La Silla Observatory. PR Photo 29a/01 : The RXJ 0529.4+0041 system before primary eclipse PR Photo 29b/01 : The RXJ 0529.4+0041 system at mid-primary eclipse PR Photo 29c/01 : The RXJ 0529.4+0041 system after primary eclipse PR Photo 29d/01 : The RXJ 0529.4+0041 system before secondary eclipse PR Photo 29e/01 : The RXJ 0529.4+0041 system at mid-secondary eclipse PR Photo 29f/01 : The RXJ 0529.4+0041 system after secondary eclipse PR Video Clip 06/01 : Video of the RXJ 0529.4+0041 system Binary stars and stellar masses Since some time, astronomers have noted that most stars seem to form in binary or multiple systems. This is quite fortunate, as the study of binary stars is the only way in which it is possible to measure directly one of the most fundamental quantities of a star, its mass. The mass of a

  15. A new technique for calculations of binary stellar evolution, with application to magnetic braking

    NASA Technical Reports Server (NTRS)

    Rappaport, S.; Joss, P. C.; Verbunt, F.

    1983-01-01

    The development of appropriate computer programs has made it possible to conduct studies of stellar evolution which are more detailed and accurate than the investigations previously feasible. However, the use of such programs can also entail some serious drawbacks which are related to the time and expense required for the work. One approach for overcoming these drawbacks involves the employment of simplified stellar evolution codes which incorporate the essential physics of the problem of interest without attempting either great generality or maximal accuracy. Rappaport et al. (1982) have developed a simplified code to study the evolution of close binary stellar systems composed of a collapsed object and a low-mass secondary. The present investigation is concerned with a more general, but still simplified, technique for calculating the evolution of close binary systems with collapsed binaries and mass-losing secondaries.

  16. Evolution of binary stars in multiple-population globular clusters - II. Compact binaries

    NASA Astrophysics Data System (ADS)

    Hong, Jongsuk; Vesperini, Enrico; Sollima, Antonio; McMillan, Stephen L. W.; D'Antona, Franca; D'Ercole, Annibale

    2016-04-01

    We present the results of a survey of N-body simulations aimed at exploring the evolution of compact binaries in multiple-population globular clusters. We show that as a consequence of the initial differences in the structural properties of the first-generation (FG) and the second-generation (SG) populations and the effects of dynamical processes on binary stars, the SG binary fraction decreases more rapidly than that of the FG population. The difference between the FG and SG binary fraction is qualitatively similar to but quantitatively smaller than that found for wider binaries in our previous investigations. The evolution of the radial variation of the binary fraction is driven by the interplay between binary segregation, ionization and ejection. Ionization and ejection counteract in part the effects of mass segregation but for compact binaries the effects of segregation dominate and the inner binary fraction increases during the cluster evolution. We explore the variation of the difference between the FG and the SG binary fraction with the distance from the cluster centre and its dependence on the binary binding energy and cluster structural parameters. The difference between the binary fraction in the FG and the SG populations found in our simulations is consistent with the results of observational studies finding a smaller binary fraction in the SG population.

  17. Surviving a School Closing

    ERIC Educational Resources Information Center

    De Witt, Peter M.; Moccia, Josephine

    2011-01-01

    When a beloved school closes, community emotions run high. De Witt and Moccia, administrators in the Averill Park School District in upstate New York, describe how their district navigated through parents' anger and practical matters in closing a small neighborhood elementary school and transferring all its students to another school. With a group…

  18. Microlensing Signature of Binary Black Holes

    NASA Technical Reports Server (NTRS)

    Schnittman, Jeremy; Sahu, Kailash; Littenberg, Tyson

    2012-01-01

    We calculate the light curves of galactic bulge stars magnified via microlensing by stellar-mass binary black holes along the line-of-sight. We show the sensitivity to measuring various lens parameters for a range of survey cadences and photometric precision. Using public data from the OGLE collaboration, we identify two candidates for massive binary systems, and discuss implications for theories of star formation and binary evolution.

  19. Detecting Near-Extremal Binary Black Holes

    NASA Astrophysics Data System (ADS)

    Hemberger, Daniel

    2014-03-01

    There is an ongoing effort in the gravitational wave astronomy community to construct a template bank for Advanced LIGO that includes gravitational waveforms from binary black hole systems with high mass ratios and spins. Using numerical relativity simulations performed with the Spectral Einstein Code, we assess the prospects for detection and parameter estimation of binaries with spins above the expected template bank cutoff spin. This analysis is restricted to equal-mass, non-precessing binaries.

  20. Survival of planets around shrinking stellar binaries

    NASA Astrophysics Data System (ADS)

    Munoz, Diego Jose; Lai, Dong

    2015-12-01

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 days, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. We present new results (PNAS 112, 30, p 9264) on the orbital evolution of planets around binaries undergoing orbital decay by this "LK+tide" mechanism. From secular and N-body calculations, we show how planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Either outcome can explain these planets' elusiveness to detection. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer specific predictions as to what their orbital configurations should be like.

  1. Survival of planets around shrinking stellar binaries.

    PubMed

    Muñoz, Diego J; Lai, Dong

    2015-07-28

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like. PMID:26159412

  2. Survival of planets around shrinking stellar binaries

    PubMed Central

    Muñoz, Diego J.; Lai, Dong

    2015-01-01

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov–Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like. PMID:26159412

  3. Survival of planets around shrinking stellar binaries.

    PubMed

    Muñoz, Diego J; Lai, Dong

    2015-07-28

    The discovery of transiting circumbinary planets by the Kepler mission suggests that planets can form efficiently around binary stars. None of the stellar binaries currently known to host planets has a period shorter than 7 d, despite the large number of eclipsing binaries found in the Kepler target list with periods shorter than a few days. These compact binaries are believed to have evolved from wider orbits into their current configurations via the so-called Lidov-Kozai migration mechanism, in which gravitational perturbations from a distant tertiary companion induce large-amplitude eccentricity oscillations in the binary, followed by orbital decay and circularization due to tidal dissipation in the stars. Here we explore the orbital evolution of planets around binaries undergoing orbital decay by this mechanism. We show that planets may survive and become misaligned from their host binary, or may develop erratic behavior in eccentricity, resulting in their consumption by the stars or ejection from the system as the binary decays. Our results suggest that circumbinary planets around compact binaries could still exist, and we offer predictions as to what their orbital configurations should be like.

  4. Tomographic reconstruction of binary fields

    NASA Astrophysics Data System (ADS)

    Roux, Stéphane; Leclerc, Hugo; Hild, François

    2012-09-01

    A novel algorithm is proposed for reconstructing binary images from their projection along a set of different orientations. Based on a nonlinear transformation of the projection data, classical back-projection procedures can be used iteratively to converge to the sought image. A multiscale implementation allows for a faster convergence. The algorithm is tested on images up to 1 Mb definition, and an error free reconstruction is achieved with a very limited number of projection data, saving a factor of about 100 on the number of projections required for classical reconstruction algorithms.

  5. Transport theory beyond binary collisions

    SciTech Connect

    Carrington, Margaret E.; Mrowczynski, Stanislaw

    2005-03-15

    Using the Schwinger-Keldysh technique, we derive the transport equations for a system of quantum scalar fields. We first discuss the general structure of the equations and then their collision terms. Taking into account up to three-loop diagrams in {phi}{sup 3} model and up to four-loop diagrams in {phi}{sup 4} model, we obtain transport equations which include the contributions of multiparticle collisions and particle production processes, in addition to mean-field effects and binary interactions.

  6. Topological-distance-dependent transition in flocks with binary interactions.

    PubMed

    Bhattacherjee, Biplab; Mishra, Shradha; Manna, S S

    2015-12-01

    We have studied a flocking model with binary interactions (binary flock), where the velocity of an agent depends on the velocity of only another agent and its own velocity, topped by the angular noise. The other agent is selected as the nth topological neighbor; the specific value of n being a fixed parameter of the problem. On the basis of extensive numerical simulation results, we argue that for n = 1, the phase transition from the ordered to the disordered phase of the flock is a special kind of discontinuous transition. Here, the order parameter does not flip-flop between multiple metastable states. It continues its initial disordered state for a period t(c), then switches over to the ordered state and remains in this state ever after. For n = 2, it is the usual discontinuous transition between two metastable states. Beyond this range, the continuous transitions are observed for n≥3. Such a system of binary flocks has been further studied using the hydrodynamic equations of motion. Linear stability analysis of the homogeneous polarized state shows that such a state is unstable close to the critical point and above some critical speed, which increases as we increase n. The critical noise strengths, which depend on the average correlation between a pair of topological neighbors, are estimated for five different values of n, which match well with their simulated values. PMID:26764659

  7. Entropy landscape of solutions in the binary perceptron problem

    NASA Astrophysics Data System (ADS)

    Huang, Haiping; Wong, K. Y. Michael; Kabashima, Yoshiyuki

    2013-09-01

    The statistical picture of the solution space for a binary perceptron is studied. The binary perceptron learns a random classification of input random patterns by a set of binary synaptic weights. The learning of this network is difficult especially when the pattern (constraint) density is close to the capacity, which is supposed to be intimately related to the structure of the solution space. The geometrical organization is elucidated by the entropy landscape from a reference configuration and of solution-pairs separated by a given Hamming distance in the solution space. We evaluate the entropy at the annealed level as well as replica symmetric level and the mean field result is confirmed by the numerical simulations on single instances using the proposed message passing algorithms. From the first landscape (a random configuration as a reference), we see clearly how the solution space shrinks as more constraints are added. From the second landscape of solution-pairs, we deduce the coexistence of clustering and freezing in the solution space.

  8. Binary tree eigen solver in finite element analysis

    NASA Technical Reports Server (NTRS)

    Akl, F. A.; Janetzke, D. C.; Kiraly, L. J.

    1993-01-01

    This paper presents a transputer-based binary tree eigensolver for the solution of the generalized eigenproblem in linear elastic finite element analysis. The algorithm is based on the method of recursive doubling, which parallel implementation of a number of associative operations on an arbitrary set having N elements is of the order of o(log2N), compared to (N-1) steps if implemented sequentially. The hardware used in the implementation of the binary tree consists of 32 transputers. The algorithm is written in OCCAM which is a high-level language developed with the transputers to address parallel programming constructs and to provide the communications between processors. The algorithm can be replicated to match the size of the binary tree transputer network. Parallel and sequential finite element analysis programs have been developed to solve for the set of the least-order eigenpairs using the modified subspace method. The speed-up obtained for a typical analysis problem indicates close agreement with the theoretical prediction given by the method of recursive doubling.

  9. Binary tree eigen solver in finite element analysis

    SciTech Connect

    Akl, F.A.; Janetzke, D.C.; Kiraly, L.J.

    1993-01-01

    This paper presents a transputer-based binary tree eigensolver for the solution of the generalized eigenproblem in linear elastic finite element analysis. The algorithm is based on the method of recursive doubling, which parallel implementation of a number of associative operations on an arbitrary set having N elements is of the order of o(log2N), compared to (N-1) steps if implemented sequentially. The hardware used in the implementation of the binary tree consists of 32 transputers. The algorithm is written in OCCAM which is a high-level language developed with the transputers to address parallel programming constructs and to provide the communications between processors. The algorithm can be replicated to match the size of the binary tree transputer network. Parallel and sequential finite element analysis programs have been developed to solve for the set of the least-order eigenpairs using the modified subspace method. The speed-up obtained for a typical analysis problem indicates close agreement with the theoretical prediction given by the method of recursive doubling. 5 refs.

  10. Resonant Raman scattering background in XRF spectra of binary samples

    NASA Astrophysics Data System (ADS)

    Sánchez, Héctor Jorge; Leani, Juan José

    2015-02-01

    In x-ray fluorescence analysis, spectra present singular characteristics produced by the different scattering processes. When atoms are irradiated with incident energy lower and close to an absorption edge, scattering peaks appear due to an inelastic process known as resonant Raman scattering. In this work we present theoretical calculations of the resonant Raman scattering contributions to the background of x-ray fluorescence spectra of binary samples of current technological or biological interest. On one hand, a binary alloy of Fe with traces of Mn (Mn: 0.01%, Fe: 99.99%) was studied because of its importance in the stainless steels industries. On the second hand a pure sample of Ti with V traces (Ti: 99%, V: 1%) was analyzed due to the current relevance in medical applications. In order to perform the calculations the Shiraiwa and Fujino's model was used to calculate characteristic intensities and scattering interactions. This model makes certain assumptions and approximations to achieve the calculations, especially in the case of the geometrical conditions and the incident and take-off beams. For the binary sample studied in this work and the considered experimental conditions, the calculations show that the resonant Raman scattering background is significant under the fluorescent peak, affects the symmetry of the peaks and, depending on the concentrations, overcomes the enhancements contributions (secondary fluorescence).

  11. Simulating merging binary black holes with nearly extremal spins

    SciTech Connect

    Lovelace, Geoffrey; Scheel, Mark A.; Szilagyi, Bela

    2011-01-15

    Astrophysically realistic black holes may have spins that are nearly extremal (i.e., close to 1 in dimensionless units). Numerical simulations of binary black holes are important tools both for calibrating analytical templates for gravitational-wave detection and for exploring the nonlinear dynamics of curved spacetime. However, all previous simulations of binary-black-hole inspiral, merger, and ringdown have been limited by an apparently insurmountable barrier: the merging holes' spins could not exceed 0.93, which is still a long way from the maximum possible value in terms of the physical effects of the spin. In this paper, we surpass this limit for the first time, opening the way to explore numerically the behavior of merging, nearly extremal black holes. Specifically, using an improved initial-data method suitable for binary black holes with nearly extremal spins, we simulate the inspiral (through 12.5 orbits), merger and ringdown of two equal-mass black holes with equal spins of magnitude 0.95 antialigned with the orbital angular momentum.

  12. The VLT-FLAMES Tarantula Survey. XXI. Stellar spin rates of O-type spectroscopic binaries

    NASA Astrophysics Data System (ADS)

    Ramírez-Agudelo, O. H.; Sana, H.; de Mink, S. E.; Hénault-Brunet, V.; de Koter, A.; Langer, N.; Tramper, F.; Gräfener, G.; Evans, C. J.; Vink, J. S.; Dufton, P. L.; Taylor, W. D.

    2015-08-01

    -star sample. The νesini distribution of binaries with amplitudes of radial velocity variation in the range of 20 to 200 kms-1 (mostly binaries with Porb ~ 10-1000 d and/or with q< 0.5) is similar to that of single O stars below νesini~< 170kms-1. Conclusions: Our results are compatible with the assumption that binary components formed with the same spin distribution as single stars, and that this distribution contains few or no fast-spinning stars. The higher average spin rate of stars in short-period binaries may either be explained by spin-up through tides in such tight binary systems, or by spin-down of a fraction of the presumed-single stars and long-period binaries through magnetic braking (or by a combination of both mechanisms). Most primaries and secondaries of SB2 systems with Porb~< 10 d appear to have similar rotational velocities. This is in agreement with tidal locking in close binaries where the components have similar radii. The lack of very rapidly spinning stars among binary systems supports the idea that most stars with νesini~> 300kms-1 in the single-star sample are actually spun-up post-binary interaction products. Finally, the overall similarities (low-velocity peak and intermediate-velocity shoulder) of the spin distribution of binary and single stars argue for a massive star formation process in which the initial spin is set independently of whether stars are formed as single stars or as components of a binary system. Based on observations collected at the European Southern Observatory under program ID 182.D-0222.Appendix A is available in electronic form at http://www.aanda.org

  13. Pseudo Algebraically Closed Extensions

    NASA Astrophysics Data System (ADS)

    Bary-Soroker, Lior

    2009-07-01

    This PhD deals with the notion of pseudo algebraically closed (PAC) extensions of fields. It develops a group-theoretic machinery, based on a generalization of embedding problems, to study these extensions. Perhaps the main result is that although there are many PAC extensions, the Galois closure of a proper PAC extension is separably closed. The dissertation also contains the following subjects. The group theoretical counterpart of pseudo algebraically closed extensions, the so-called projective pairs. Applications to seemingly unrelated subjects, e.g., an analog of Dirichlet's theorem about primes in arithmetic progression for polynomial rings in one variable over infinite fields.

  14. Red Giants in Eclipsing Binaries as a Benchmark for Asteroseismology

    NASA Astrophysics Data System (ADS)

    Rawls, Meredith L.

    2016-04-01

    unprecedented opportunity to test stellar physics and are important benchmarks for ensemble asteroseismology. Future asteroseismic studies should know they are excluding magnetically active stars and close binaries and be aware that asteroseismic masses and radii are both overestimated.

  15. Red Giants in Eclipsing Binaries as a Benchmark for Asteroseismology

    NASA Astrophysics Data System (ADS)

    Rawls, Meredith L.

    2016-04-01

    unprecedented opportunity to test stellar physics and are important benchmarks for ensemble asteroseismology. Future asteroseismic studies should know they are excluding magnetically active stars and close binaries and be aware that asteroseismic masses and radii are both overestimated.

  16. Cost-Sensitive Local Binary Feature Learning for Facial Age Estimation.

    PubMed

    Lu, Jiwen; Liong, Venice Erin; Zhou, Jie

    2015-12-01

    In this paper, we propose a cost-sensitive local binary feature learning (CS-LBFL) method for facial age estimation. Unlike the conventional facial age estimation methods that employ hand-crafted descriptors or holistically learned descriptors for feature representation, our CS-LBFL method learns discriminative local features directly from raw pixels for face representation. Motivated by the fact that facial age estimation is a cost-sensitive computer vision problem and local binary features are more robust to illumination and expression variations than holistic features, we learn a series of hashing functions to project raw pixel values extracted from face patches into low-dimensional binary codes, where binary codes with similar chronological ages are projected as close as possible, and those with dissimilar chronological ages are projected as far as possible. Then, we pool and encode these local binary codes within each face image as a real-valued histogram feature for face representation. Moreover, we propose a cost-sensitive local binary multi-feature learning method to jointly learn multiple sets of hashing functions using face patches extracted from different scales to exploit complementary information. Our methods achieve competitive performance on four widely used face aging data sets. PMID:26415174

  17. MASS TRANSFER IN BINARY STARS USING SMOOTHED PARTICLE HYDRODYNAMICS. I. NUMERICAL METHOD

    SciTech Connect

    Lajoie, Charles-Philippe; Sills, Alison E-mail: asills@mcmaster.ca

    2011-01-10

    Close interactions and mass transfer in binary stars can lead to the formation of many different exotic stellar populations, but detailed modeling of mass transfer is a computationally challenging problem. Here, we present an alternate smoothed particle hydrodynamics approach to the modeling of mass transfer in binary systems that allows a better resolution of the flow of matter between main-sequence stars. Our approach consists of modeling only the outermost layers of the stars using appropriate boundary conditions and ghost particles. We arbitrarily set the radius of the boundary and find that our boundary treatment behaves physically and conserves energy well. In particular, when used with our binary relaxation procedure, our treatment of boundary conditions is also shown to evolve circular binaries properly for many orbits. The results of our first simulation of mass transfer are also discussed and used to assess the strengths and limitations of our method. We conclude that it is well suited for the modeling of interacting binary stars. The method presented here represents a convenient alternative to previous hydrodynamical techniques aimed at modeling mass transfer in binary systems since it can be used to model both the donor and the accretor while maintaining the density profiles taken from realistic stellar models.

  18. Black holes in stellar-mass binary systems: expiating original spin?

    NASA Astrophysics Data System (ADS)

    King, Andrew; Nixon, Chris

    2016-10-01

    We investigate systematically whether accreting black hole systems are likely to reach global alignment of the black hole spin and its accretion disc with the binary plane. In low-mass X-ray binaries (LMXBs), there is only a modest tendency to reach such global alignment, and it is difficult to achieve fully: except for special initial conditions, we expect misalignment of the spin and orbital planes by ˜1 rad for most of the LMXB lifetime. The same is expected in high-mass X-ray binaries. A fairly close approach to global alignment is likely in most stellar-mass ultraluminous X-ray binary systems (ULXs) where the companion star fills its Roche lobe and transfers mass on a thermal or nuclear time-scale to a black hole of lower mass. These systems are unlikely to show orbital eclipses, as their emission cones are close to the hole's spin axis. This offers a potential observational test, as models for ULXs invoking intermediate-mass black holes do predict eclipses for ensembles of ≳ 10 systems. Recent observational work shows that eclipses are either absent or extremely rare in ULXs, supporting the picture that most ULXs are stellar-mass binaries with companion stars more massive than the accretor.

  19. Discovery of a 66 mas Ultracool Binary with Laser Guide Star Adaptive Optics

    SciTech Connect

    Siegler, N; Close, L; Burgasser, A; Cruz, K; Marois, C; Macintosh, B; Barman, T

    2007-02-02

    We present the discovery of 2MASS J21321145+1341584AB as a closely separated (0.066'') very low-mass field dwarf binary resolved in the near-infrared by the Keck II Telescope using laser guide star adaptive optics. Physical association is deduced from the angular proximity of the components and constraints on their common proper motion. We have obtained a near-infrared spectrum of the binary and find that it is best described by an L5{+-}0.5 primary and an L7.5{+-}0.5 secondary. Model-dependent masses predict that the two components straddle the hydrogen burning limit threshold with the primary likely stellar and the secondary likely substellar. The properties of this sytem - close projected separation (1.8{+-}0.3AU) and near unity mass ratio - are consistent with previous results for very low-mass field binaries. The relatively short estimated orbital period of this system ({approx}7-12 yr) makes it a good target for dynamical mass measurements. Interestingly, the system's angular separation is the tightest yet for any very low-mass binary published from a ground-based telescope and is the tightest binary discovered with laser guide star adaptive optics to date.

  20. Interacting jets from binary protostars

    NASA Astrophysics Data System (ADS)

    Murphy, G. C.; Lery, T.; O'Sullivan, S.; Spicer, D.; Bacciotti, F.; Rosen, A.

    2008-02-01

    Aims: We investigate potential models that could explain why multiple proto-stellar systems predominantly show single jets. During their formation, stars most frequently produce energetic outflows and jets. However, binary jets have only been observed in a very small number of systems. Methods: We model numerically 3D binary jets for various outflow parameters. We also model the propagation of jets from a specific source, namely L1551 IRS 5, known to have two jets, using recent observations as constraints for simulations with a new MHD code. We examine their morphology and dynamics, and produce synthetic emission maps. Results: We find that the two jets interfere up to the stage where one of them is almost destroyed or engulfed into the second one. We are able to reproduce some of the observational features of L1551 such as the bending of the secondary jet. Conclusions: While the effects of orbital motion are negligible over the jets dynamical timeline, their interaction has significant impact on their morphology. If the jets are not strictly parallel, as in most observed cases, we show that the magnetic field can help the collimation and refocusing of both of the two jets.

  1. Odour suppression in binary mixtures.

    PubMed

    Cashion, Larry; Livermore, Andrew; Hummel, Thomas

    2006-10-01

    It has been suggested that odours causing stronger trigeminal activation suppress weaker trigeminal stimuli and that mixed olfactory-trigeminal stimuli suppress odorants that only activate one of these systems. Volunteer normosmic participants (n=20) were exposed to six odorants with varying trigeminal impact to test the hypothesis that more intense "trigeminal" odorants would suppress weaker trigeminal stimuli in binary odour mixtures. It was also hypothesised that stronger trigeminal odorants would dominate six-odour mixtures. The predicted linear pattern of suppression was not seen, with a quadratic model emerging from the data. Stronger trigeminal stimuli failed to dominate six-odour mixtures. Despite the fact that the major hypothesis was not supported, it can be hypothesised from this experiment that the effect of suppression in binary mixtures is reliant upon two major effects: (1) the association formed between odours and the multiple memory systems that they interact with during the encoding and recognition processes, and (2) the balance between activation of the olfactory and trigeminal systems.

  2. Mutual Orbits of Transneptunian Binaries

    NASA Astrophysics Data System (ADS)

    Grundy, William M.; Noll, K. S.; Roe, H. G.; Porter, S. B.; Trujillo, C. A.; Benecchi, S. D.; Buie, M. W.

    2012-10-01

    We report the latest results from a program of high spatial resolution imaging to resolve the individual components of binary transneptunian objects. These observations use Hubble Space Telescope and also laser guide star adaptive optics systems on Keck and Gemini telescopes on Mauna Kea. From relative astrometry over multiple epochs, we determine the mutual orbits of the components, and thus the total masses of the systems. Accurate masses anchor subsequent detailed investigations into the physical characteristics of these systems. For instance, dynamical masses enable computation of bulk densities for systems where the component sizes can be estimated from other measurements. Additionally, patterns in the ensemble characteristics of binary orbits offer clues to circumstances in the protoplanetary nebula when these systems formed, as well as carrying imprints of various subsequent dynamical evolution processes. The growing ensemble of known orbits shows intriguing patterns that can shed light on the evolution of this population of distant objects. This work has been supported by an NSF Planetary Astronomy grant and by several Hubble Space Telescope and NASA Keck data analysis grants. The research makes use of data from the Gemini Observatory obtained through NOAO survey program 11A-0017, from a large number of Hubble Space Telescope programs, and from several NASA Keck programs.

  3. Direct band gaps in group IV-VI monolayer materials: Binary counterparts of phosphorene

    NASA Astrophysics Data System (ADS)

    Kamal, C.; Chakrabarti, Aparna; Ezawa, Motohiko

    2016-03-01

    We perform systematic investigation on the geometric, energetic, and electronic properties of group IV-VI binary monolayers (XY ), which are the counterparts of phosphorene, by employing density functional theory based electronic structure calculations. For this purpose, we choose the binary systems X Y consisting of equal numbers of group IV (X = C, Si, Ge, Sn) and group VI elements (Y = O, S, Se, Te) in three geometrical configurations, the puckered, buckled and planar structures. The results of binding energy calculations show that all the binary systems studied are energetically stable. It is observed that, the puckered structure, similar to that of phosphorene, is the energetically most stable geometric configuration. Moreover, the binding energies of buckled configuration are very close to those of the puckered configuration. Our results of electronic band structure predict that puckered SiO and CSe are direct band semiconductors with gaps of 1.449 and 0.905 eV, respectively. Band structure of CSe closely resembles that of phosphorene. Remaining group IV-VI binary monolayers in the puckered configuration and all the buckled monolayers are also semiconductors, but with indirect band gaps. Importantly, we find that the difference between indirect and direct band gaps is very small for many puckered monolayers. Thus there is a possibility of making these systems undergo transition from indirect to direct band gap semiconducting state by a suitable external influence. Indeed, we show in the present work that seven binary monolayers, namely, SnS, SiSe, GeSe, SnSe, SiTe, GeTe, and SnTe become direct band gap semiconductors when they are subjected to a small mechanical strain (≤3 % ). This makes nine out of sixteen binary monolayers studied in the present work direct band gap semiconductors. Thus there is a possibility of utilizing these binary counterparts of phosphorene in future light-emitting diodes and solar cells.

  4. Abell 41: shaping of a planetary nebula by a binary central star

    NASA Astrophysics Data System (ADS)

    Jones, D.; Lloyd, M.; Santander-García, M.; López, J. A.; Meaburn, J.; Mitchell, D. L.; O'Brien, T. J.; Pollacco, D.; Rubio-Díez, M. M.; Vaytet, N. M. H.

    2010-11-01

    We present the first detailed spatiokinematical analysis and modelling of the planetary nebula Abell 41, which is known to contain the well-studied close-binary system MT Ser. This object represents an important test case in the study of the evolution of planetary nebulae with binary central stars as current evolutionary theories predict that the binary plane should be aligned perpendicular to the symmetry axis of the nebula. Deep narrow-band imaging in the light of [NII]6584Å, [OIII]5007 Å and [SII]6717+6731Å, obtained using ACAM on the William Herschel Telescope, has been used to investigate the ionization structure of Abell 41. Long-slit observations of the Hα and [NII]6584Å emission were obtained using the Manchester Echelle Spectrometer on the 2.1-m San Pedro Mártir Telescope. These spectra, combined with the narrow-band imagery, were used to develop a spatiokinematical model of [NII]6584Å emission from Abell 41. The best-fitting model reveals Abell 41 to have a waisted, bipolar structure with an expansion velocity of ~40 km s-1 at the waist. The symmetry axis of the model nebula is within 5° of perpendicular to the orbital plane of the central binary system. This provides strong evidence that the close-binary system, MT Ser, has directly affected the shaping of its nebula, Abell 41. Although the theoretical link between bipolar planetary nebulae and binary central stars is long established, this nebula is only the second to have this link, between nebular symmetry axis and binary plane, proved observationally. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. E-mail: david.jones-3@postgrad.manchester.ac.uk

  5. Closed Large Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

    article title:  Closed Large Cell Clouds in the South Pacific     ... unperturbed by cyclonic or frontal activity. When the cell centers are cloudy and the main sinking motion is concentrated at cell ...

  6. The Frequency of Binary Star Interlopers Amongst Transitional Disks.

    NASA Astrophysics Data System (ADS)

    Ruíz-Rodríguez, D.; Ireland, M.; Cieza, L.; Kraus, A.

    2016-09-01

    Using Non-Redundant Mask interferometry (NRM), we searched for binary companions to objects previously classified as Transitional Disks (TD). These objects are thought to be an evolutionary stage between an optically thick disk and optically thin disk. We investigate the presence of a stellar companion as a possible mechanism of material depletion in the inner region of these disks, which would rule out an ongoing planetary formation process in distances comparable to the binary separation. For our detection limits, we implement a new method of completeness correction using a combination of randomly sampled binary orbits and Bayesian inference. The selected sample of 24 TDs belong to the nearby and young star forming regions: Ophiuchus (˜ 130 pc), Taurus-Auriga (˜ 140 pc) and IC348 ( ˜ 220 pc). These regions are suitable to resolve faint stellar companions with moderate to high confidence levels at distances as low as 2 au from the central star. With a total of 31 objects, including 11 known TDs and circumbinary disks from the literature, we have found that a fraction of 0.38 ± 0.09 of the SEDs of these objects are likely due to the tidal interaction between a close binary and its disk, while the remaining SEDs are likely the result of other internal processes such as photoevaporation, grain growth, planet disk interactions. In addition, we detected four companions orbiting outside the area of the truncation radii and we propose that the IR excesses of these systems are due to a disk orbiting a secondary companion

  7. Wolf-Rayet stars in the Small Magellanic Cloud. II. Analysis of the binaries

    NASA Astrophysics Data System (ADS)

    Shenar, T.; Hainich, R.; Todt, H.; Sander, A.; Hamann, W.-R.; Moffat, A. F. J.; Eldridge, J. J.; Pablo, H.; Oskinova, L. M.; Richardson, N. D.

    2016-06-01

    Context. Massive Wolf-Rayet (WR) stars are evolved massive stars (Mi ≳ 20 M⊙) characterized by strong mass-loss. Hypothetically, they can form either as single stars or as mass donors in close binaries. About 40% of all known WR stars are confirmed binaries, raising the question as to the impact of binarity on the WR population. Studying WR binaries is crucial in this context, and furthermore enable one to reliably derive the elusive masses of their components, making them indispensable for the study of massive stars. Aims: By performing a spectral analysis of all multiple WR systems in the Small Magellanic Cloud (SMC), we obtain the full set of stellar parameters for each individual component. Mass-luminosity relations are tested, and the importance of the binary evolution channel is assessed. Methods: The spectral analysis is performed with the Potsdam Wolf-Rayet (PoWR) model atmosphere code by superimposing model spectra that correspond to each component. Evolutionary channels are constrained using the Binary Population and Spectral Synthesis (BPASS) evolution tool. Results: Significant hydrogen mass fractions (0.1 binary AB 6 is found to be very luminous (log L ≈ 6.3 [L⊙]) given its orbital mass (≈10 M⊙), presumably because of observational contamination by a third component. Evolutionary paths derived for our objects suggest that Roche lobe overflow had occurred in most systems, affecting their evolution. However, the implied initial masses (≳60 M⊙) are large enough for the primaries to have entered the WR phase, regardless of binary interaction. Conclusions: Together with the results for the putatively single SMC WR stars, our study suggests that the binary evolution channel does not dominate the formation of WR stars at

  8. Fill-in binary loop pulse-torque quantizer

    NASA Technical Reports Server (NTRS)

    Lory, C. B.

    1975-01-01

    Fill-in binary (FIB) loop provides constant heating of torque generator, an advantage of binary current switching. At the same time, it avoids mode-related dead zone and data delay of binary, an advantage of ternary quantization.

  9. Fabricating binary optics: An overview of binary optics process technology

    NASA Technical Reports Server (NTRS)

    Stern, Margaret B.

    1993-01-01

    A review of binary optics processing technology is presented. Pattern replication techniques have been optimized to generate high-quality efficient microoptics in visible and infrared materials. High resolution optical photolithography and precision alignment is used to fabricate maximally efficient fused silica diffractive microlenses at lambda = 633 nm. The degradation in optical efficiency of four-phase-level fused silica microlenses resulting from an intentional 0.35 micron translational error has been systematically measured as a function of lens speed (F/2 - F/60). Novel processes necessary for high sag refractive IR microoptics arrays, including deep anisotropic Si-etching, planarization of deep topography and multilayer resist techniques, are described. Initial results are presented for monolithic integration of photonic and microoptic systems.

  10. Gravitational radiation, inspiraling binaries, and cosmology

    NASA Technical Reports Server (NTRS)

    Chernoff, David F.; Finn, Lee S.

    1993-01-01

    We show how to measure cosmological parameters using observations of inspiraling binary neutron star or black hole systems in one or more gravitational wave detectors. To illustrate, we focus on the case of fixed mass binary systems observed in a single Laser Interferometer Gravitational-wave Observatory (LIGO)-like detector. Using realistic detector noise estimates, we characterize the rate of detections as a function of a threshold SNR Rho(0), H0, and the binary 'chirp' mass. For Rho(0) = 8, H0 = 100 km/s/Mpc, and 1.4 solar mass neutron star binaries, the sample has a median redshift of 0.22. Under the same assumptions but independent of H0, a conservative rate density of coalescing binaries implies LIGO will observe about 50/yr binary inspiral events. The precision with which H0 and the deceleration parameter q0 may be determined depends on the number of observed inspirals. For fixed mass binary systems, about 100 observations with Rho(0) = 10 in the LIGO will give H0 to 10 percent in an Einstein-DeSitter cosmology, and 3000 will give q0 to 20 percent. For the conservative rate density of coalescing binaries, 100 detections with Rho(0) = 10 will require about 4 yrs.

  11. An Acidity Scale for Binary Oxides.

    ERIC Educational Resources Information Center

    Smith, Derek W.

    1987-01-01

    Discusses the classification of binary oxides as acidic, basic, or amphoteric. Demonstrates how a numerical scale for acidity/basicity of binary oxides can be constructed using thermochemical data for oxoacid salts. Presents the calculations derived from the data that provide the numeric scale values. (TW)

  12. ECCENTRIC EVOLUTION OF SUPERMASSIVE BLACK HOLE BINARIES

    SciTech Connect

    Iwasawa, Masaki; An, Sangyong; Matsubayashi, Tatsushi; Funato, Yoko; Makino, Junichiro

    2011-04-10

    In recent numerical simulations, it has been found that the eccentricity of supermassive black hole (SMBH)-intermediate black hole (IMBH) binaries grows toward unity through interactions with the stellar background. This increase of eccentricity reduces the merging timescale of the binary through the gravitational radiation to a value well below the Hubble time. It also gives a theoretical explanation of the existence of eccentric binaries such as that in OJ287. In self-consistent N-body simulations, this increase of eccentricity is always observed. On the other hand, the result of the scattering experiment between SMBH binaries and field stars indicated that the eccentricity dose not change significantly. This discrepancy leaves the high eccentricity of the SMBH binaries in N-body simulations unexplained. Here, we present a stellar-dynamical mechanism that drives the increase of the eccentricity of an SMBH binary with a large mass ratio. There are two key processes involved. The first one is the Kozai mechanism under a non-axisymmetric potential, which effectively randomizes the angular momenta of surrounding stars. The other is the selective ejection of stars with prograde orbits. Through these two mechanisms, field stars extract the orbital angular momentum of the SMBH binary. Our proposed mechanism causes the increase in the eccentricity of most of SMBH binaries, resulting in the rapid merger through gravitational wave radiation. Our result has given a definite solution to the 'last-parsec problem'.

  13. EQUILIBRIUM CONFIGURATIONS OF SYNCHRONOUS BINARIES: NUMERICAL SOLUTIONS AND APPLICATION TO KUIPER BELT BINARY 2001 QG{sub 298}

    SciTech Connect

    Gnat, Orly; Sari, Re'em

    2010-08-20

    We present numerical computations of the equilibrium configurations of tidally locked homogeneous binaries rotating in circular orbits. Unlike the classical Roche approximations, we self-consistently account for the tidal and rotational deformations of both components, and relax the assumptions of ellipsoidal configurations and Keplerian rotation. We find numerical solutions for mass ratios q between 10{sup -3} and 1, starting at a small angular velocity for which tidal and rotational deformations are small, and following a sequence of increasing angular velocities. Each series terminates at an appropriate 'Roche limit', above which no equilibrium solution can be found. Even though the Roche limit is crossed before the 'Roche lobe' is filled, any further increase in the angular velocity will result in mass-loss. For close, comparable-mass binaries, we find that local deviations from ellipsoidal forms may be as large as 10%-20%, and departures from Keplerian rotation are significant. We compute the light curves that arise from our equilibrium configurations, assuming their distance is >>1 AU (e.g., in the Kuiper Belt). We consider both backscatter (proportional to the projected area) and diffuse (Lambert) reflections. Backscatter reflection always yields two minima of equal depths. Diffuse reflection, which is sensitive to the surface curvature, generally gives rise to unequal minima. We find detectable intensity differences of up to 10% between our light curves and those arising from the Roche approximations. Finally, we apply our models to Kuiper Belt binary 2001 QG{sub 298}, and find a nearly edge-on binary with a mass ratio q = 0.93{sup +0.07}{sub -0.03}, angular velocity {omega}{sup 2}/G{rho} = 0.333 {+-} 0.001 (statistical errors only), and pure diffuse reflection. For the observed period of 2001 QG{sub 298}, these parameters imply a bulk density {rho} = 0.72 {+-} 0.04 g cm{sup -3}.

  14. Triple Collision and Close Triple Encounters

    NASA Astrophysics Data System (ADS)

    Waldvogel, Joerg

    In gravitational systems of point masses binary collisions are mathematically simple and well understood. Collisions of three or more particles are much more complicated, i.e. a dramatic increase of complexity occurs when the number N of particles involved in a collision increases from 2 to 3. Collisions of more than three particles seem to be of the same complexity as triple collisions. However, there are still unanswered questions concerning general N-body collisions.The reason for the complexity of triple collision is the inherent sensitivity to initial conditions for solutions passing near triple collision, even after a short time. Specifically, a solution passing near triple collision may change dramatically if the initial conditions prior to the close encounter are modified infinitesimally. In contrast, this is not the case for a binary collision.We use the planar three-body problem as a model in order to discuss the main features of triple collision of point masses and of its realistic counterpart, the close triple encounter. This comparatively simple model allows us to study all important aspects of close encounters of N > 2 gravitationally interacting point masses.In Chapters 1 and 2 we discuss classical results, beginning with the equations of motion, then studying relationships between the total angular momentum and triple collision. C. L. Siegel's famous series for triple collision solutions, one time considered the highlight of the theory of triple collision, conclude the traditional part of these lectures.Chapter 3 is devoted to studying the relationship between solutions engaging in a sharp triple collision and neighbouring solutions. The variational equation gives a rough idea of what is happening. A complete understanding can be achieved by means of R. McGehee's concept of the collision manifold, which arises by introducing special coordinates blowing up all possible states close to triple collision. In this context, possibilities of regularizing

  15. Asteroid Systems: Binaries, Triples, and Pairs

    NASA Astrophysics Data System (ADS)

    Margot, J.-L.; Pravec, P.; Taylor, P.; Carry, B.; Jacobson, S.

    In the past decade, the number of known binary near-Earth asteroids has more than quadrupled and the number of known large main-belt asteroids with satellites has doubled. Half a dozen triple asteroids have been discovered, and the previously unrecognized populations of asteroid pairs and small main-belt binaries have been identified. The current observational evidence confirms that small (≲20 km) binaries form by rotational fission and establishes that the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect powers the spin-up process. A unifying paradigm based on rotational fission and post-fission dynamics can explain the formation of small binaries, triples, and pairs. Large (>~20 km) binaries with small satellites are most likely created during large collisions.

  16. A radio-pulsing white dwarf binary star

    NASA Astrophysics Data System (ADS)

    Marsh, T. R.; Gänsicke, B. T.; Hümmerich, S.; Hambsch, F.-J.; Bernhard, K.; Lloyd, C.; Breedt, E.; Stanway, E. R.; Steeghs, D. T.; Parsons, S. G.; Toloza, O.; Schreiber, M. R.; Jonker, P. G.; van Roestel, J.; Kupfer, T.; Pala, A. F.; Dhillon, V. S.; Hardy, L. K.; Littlefair, S. P.; Aungwerojwit, A.; Arjyotha, S.; Koester, D.; Bochinski, J. J.; Haswell, C. A.; Frank, P.; Wheatley, P. J.

    2016-09-01

    White dwarfs are compact stars, similar in size to Earth but approximately 200,000 times more massive. Isolated white dwarfs emit most of their power from ultraviolet to near-infrared wavelengths, but when in close orbits with less dense stars, white dwarfs can strip material from their companions and the resulting mass transfer can generate atomic line and X-ray emission, as well as near- and mid-infrared radiation if the white dwarf is magnetic. However, even in binaries, white dwarfs are rarely detected at far-infrared or radio frequencies. Here we report the discovery of a white dwarf/cool star binary that emits from X-ray to radio wavelengths. The star, AR Scorpii (henceforth AR Sco), was classified in the early 1970s as a δ-Scuti star, a common variety of periodic variable star. Our observations reveal instead a 3.56-hour period close binary, pulsing in brightness on a period of 1.97 minutes. The pulses are so intense that AR Sco’s optical flux can increase by a factor of four within 30 seconds, and they are also detectable at radio frequencies. They reflect the spin of a magnetic white dwarf, which we find to be slowing down on a 107-year timescale. The spin-down power is an order of magnitude larger than that seen in electromagnetic radiation, which, together with an absence of obvious signs of accretion, suggests that AR Sco is primarily spin-powered. Although the pulsations are driven by the white dwarf’s spin, they mainly originate from the cool star. AR Sco’s broadband spectrum is characteristic of synchrotron radiation, requiring relativistic electrons. These must either originate from near the white dwarf or be generated in situ at the M star through direct interaction with the white dwarf’s magnetosphere.

  17. Enhancement of dark matter capture by neutron stars in binary systems.

    PubMed

    Brayeur, Lionel; Tinyakov, Peter

    2012-08-10

    We study the capture of dark matter particles by neutron stars in close binary systems. By performing a direct numerical simulation, we find that there is a sizable amplification of the rate of dark matter capture by each of the companions. In the case of the binary pulsar PSR J1906+0746 with the orbital period of 4 hours the amplification factor is approximately equal to 3.5. This amplification can be attributed to the energy loss by dark matter particles resulting from their gravitational scattering off moving companions.

  18. Algebraic classification of numerical spacetimes and black-hole-binary remnants

    NASA Astrophysics Data System (ADS)

    Campanelli, Manuela; Lousto, Carlos O.; Zlochower, Yosef

    2009-04-01

    In this paper we develop a technique for determining the algebraic classification of a numerically generated spacetime, possibly resulting from a generic black-hole-binary merger, using the Newman-Penrose Weyl scalars. We demonstrate these techniques for a test case involving a close binary with arbitrarily oriented spins and unequal masses. We find that, postmerger, the spacetime quickly approaches Petrov type II, and only approaches type D on much longer time scales. These techniques, in combination with techniques for evaluating acceleration and Newman-Unti-Tamburino parameters, allow us to begin to explore the validity of the “no-hair theorem” for generic merging-black-hole spacetimes.

  19. Algebraic Classification of Numerical Spacetimes and Black-Hole-Binary Remnants

    NASA Astrophysics Data System (ADS)

    Campanelli, Manuela; Lousto, Carlos; Zlochower, Yosef

    2009-05-01

    In this paper we develop a technique for determining the algebraic classification of a numerical spacetime, possibly resulting from a generic black-hole-binary merger, using the Newman-Penrose Weyl scalars. We demonstrate these techniques for a test case involving a close binary with arbitrarily oriented spins and unequal masses. We find that, post merger, the spacetime quickly approaches Petrov type II, and only approaches type D on much longer timescales. These techniques allow us to begin to explore the validity of the ``no-hair theorem'' for generic merging-black-hole spacetimes

  20. O'Connell Effect in Early-Type Contact(?) Binaries: du Boo and AG Vir

    NASA Astrophysics Data System (ADS)

    Pribulla, Theodor; Vaňko, Martin; Chochol, Drahomír; Hambálek, L'ubomıır; Parimucha, Štefan

    2010-12-01

    O'Connell effect in early-type close eclipsing binaries is not caused by solar-type spots. In most early-type contact binaries it has the same sign: maximum following the primary minimum being the brighter of the two. Broadening functions of two early-type systems, DU Boo and AG Vir, do not show presence of dark solar-type spots in spite of strong light-curve asymmetry but indicate departures from the Roche model and/or possibly additional structures (stream, disc, etc.).

  1. Formation and Evolution of Circumbinary Planets, and the Apparent Lack of CPBs Around Short-Period Binaries

    NASA Astrophysics Data System (ADS)

    Haghighipour, Nader

    2015-12-01

    The success of the Kepler space telescope in detecting planets in circumbinary orbits strongly suggests that planet formation around binary stars is robust and planets of a variety of sizes and orbital configurations may exist in such complex environments. Accurate modeling of Kepler data has also indicated that some of these planets orbit their central binaries in close proximity to the boundary of orbital stability. This finding, combined with the unsuccessful attempts in forming circumbinary planets (CBPs) close to the orbital stability limit has lent strong support to the idea that almost all currently known CBPs have formed at large distances and undergone substantial radial migration. A survey of the currently known CBPs further indicates that these planets are mainly Neptune-mass and there seems to be a lack of planets of Jupiter-mass or larger in P-type orbits. Furthermore, an examination of the observational data obtained by the Kepler telescope seems to suggest an absence of CBPs around short-period binaries. Finally, recent detections of episodic transits in the two newly discovered circumbinary systems, Kepler 413b and Kepler 453b, as well as the discovery of Kepler non-transiting CBPs, (please see the abstract by Fabrycky et al) have indicated that in general, the orbits of planets and their host binaries are not co-planar. We present a new model for the formation and evolution of CBPs in which the migration of CBPs has been studied for low and high eccentricity binaries, and for different values of binary period. Results of our extensive hydrodynamical simulations show that planet-disk interaction in low-eccentricity binaries can account for the migration of CBPs and the proximity of their final orbits to the boundary of stability. In eccentric binaries, the situation is, however, more complex and in order to explain the final orbital architecture of the system, other factors such as planet-planet interaction have to be taken into account. We show

  2. Secular resonances in circumstellar systems in binary stars

    NASA Astrophysics Data System (ADS)

    Bazso, A.; Pilat-Lohinger, E.; Eggl, S.; Funk, B.; Bancelin, D.

    2016-02-01

    Planet formation around single stars is already a complicated matter, but extrasolar planets are also present in binary and multiple star systems. We investigate circumstellar planets in binary star systems with stellar separations below 100 astronomical units. For a selection of 11 systems with at least one detected giant planet we determine the location and extension of the habitable zone (HZ), subject to the incident stellar flux from both stars. We work out the stability of additional hypothetical terrestrial planets in or close to the HZ in these systems. To study the secular dynamics we apply a semi-analytical method. This method employs a first-order perturbation theory to determine the secular frequencies of objects moving under the gravitational influence of two much more massive perturbers. The other part uses a single numerical integration of the equations of motion and a frequency analysis of the obtained time-series to determine the apsidal precession frequencies of the massive bodies. By combining these two parts we are able to find the location of the most important secular resonances and the regions of chaotic motion. We demonstrate that terrestrial planets interior to the giant planet’s orbit may suffer from a linear secular resonance that could prevent the existence of habitable planets. Contrary to this, close-in giant planets are less of a problem, but one has to take into account the general relativistic precession of the pericenter that can also lead to resonances.

  3. Record-Breaking Eclipsing Binary

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-05-01

    A new record holder exists for the longest-period eclipsing binary star system: TYC-2505-672-1. This intriguing system contains a primary star that is eclipsed by its companion once every 69 years with each eclipse lasting several years!120 Years of ObservationsIn a recent study, a team of scientists led by Joseph Rodriguez (Vanderbilt University) characterizes the components of TYC-2505-672-1. This binary star system consists of an M-type red giant star that undergoes a ~3.45-year-long, near-total eclipse with a period of ~69.1 years. This period is more than double that of the previous longest-period eclipsing binary!Rodriguez and collaborators combined photometric observations of TYC-2505-672-1 by the Kilodegree Extremely Little Telescope (KELT) with a variety of archival data, including observations by the American Association of Variable Star Observers (AAVSO) network and historical data from the Digital Access to a Sky Century @ Harvard (DASCH) program.In the 120 years spanned by these observations, two eclipses are detected: one in 1942-1945 and one in 2011-2015. The authors use the observations to analyze the components of the system and attempt to better understand what causes its unusual light curve.Characterizing an Unusual SystemObservations of TYC-2505-672-1 plotted from 1890 to 2015 reveal two eclipses. (The blue KELT observations during the eclipse show upper limits only.) [Rodriguez et al. 2016]By modeling the systems emission, Rodriguez and collaborators establish that TYC-2505-672-1 consists of a 3600-K primary star thats the M giant orbited by a small, hot, dim companion thats a toasty 8000 K. But if the companion is small, why does the eclipse last several years?The authors argue that the best model of TYC-2505-672-1 is one in which the small companion star is surrounded by a large, opaque circumstellar disk. Rodriguez and collaborators suggest that the companion could be a former red giant whose atmosphere was stripped from it, leaving behind

  4. Grafts in "closed" rhinoplasty.

    PubMed

    Scattolin, A; D'Ascanio, L

    2013-06-01

    Rhinoplasty is a fascinating and complex surgical procedure aiming at attaining a well-functioning and aesthetically pleasant nose. The use of grafts is of the utmost importance for the nasal surgeon to achieve such results. However, the philosophy and technical use of nasal grafts are different in "closed" and "open" rhinoplasty. The aim of this paper is not detailed description of the numerous grafts reported in the literature; we will describe the main principles of grafts use in "closed" rhinoplasty derived from our experience, with special reference to the philosophical and technical differences in their employment between "closed" and "open" rhinoplasty. Some cases are reported as an example of graft use in "endonasal" approach rhinoplasty.

  5. Binary Systems Within Star Clusters

    NASA Astrophysics Data System (ADS)

    Paunzen, Ernst; Stütz, Christian; Baumann, Bernhard

    2012-04-01

    WEBDA (http://www.univie.ac.at/webda) is a site devoted to observational data of stellar clusters in the Milky Way and the Small Magellanic Cloud. It is intended to provide a reliable presentation of the available data and knowledge about these objects. The success of WEBDA is documented by its worldwide usage and the related acknowledgements in the literature: more than 650 refereed publications within the last twelve years acknowledged its use. It collects all published data for stars in open clusters that may be useful either to determine membership, or to study the stellar content and properties of the clusters. The database content includes astrometric data in the form of coordinates, rectangular positions, and proper motions, photometric data in the major systems in which star clusters have been observed, but also spectroscopic data like spectral classification, radial velocities, and rotational velocities. It also contains miscellaneous types of supplementary data like membership probabilities, orbital elements of spectroscopic binaries, and periods for different kinds of variable stars as well as an extensive bibliography. Several powerful tools help to plot, query and extract the data, which can be directly retrieved via http. At the time of writing, about four million individual measurements have been included in the database. The Star Clusters Young & Old Newsletter (SCYON), a bi-monthly newsletter devoted to star cluster research with about 600 subscribers, is hosted in parallel with the database. We present the current and upcoming new interface and tools, which are needed to visualize and analyze the increasing amount of data from all-sky surveys, and deeper investigations of binary systems, low mass dwarfs, as well as planet-hosting stars.

  6. Closing the Loop Sampler.

    ERIC Educational Resources Information Center

    California Integrated Waste Management Board, Sacramento.

    Closing the Loop (CTL) is a science curriculum designed to introduce students to integrated waste management through awareness. This document presents five lesson plans focusing on developing an understanding of natural resources, solid wastes, conservation, and the life of landfills. Contents include: (1) "What Are Natural Resources?"; (2)…

  7. Closing the Performance Gap.

    ERIC Educational Resources Information Center

    Riggins, Cheryl G.

    2002-01-01

    Describes how the principal of a K-2, 400-student suburban elementary school near Flint, Michigan, worked with her staff and superintendent to develop and implement a strategic plan to close the student achievement gap. Reports significant improvement in reading and math scores after 1 year. (PKP)

  8. Review: The Closing Circle

    ERIC Educational Resources Information Center

    Environment, 1972

    1972-01-01

    Two views of prominent biologists are presented side-by-side. Focal point is Barry Commoner's book, The Closing Circle, with a subsequent review by Paul Ehrlich. Growth of population, increases in affluence, and increased pollution from products of technology are considered. (BL)

  9. Closed Small Cell Clouds

    Atmospheric Science Data Center

    2013-04-19

    ... (right)   The structure of tightly packed "closed cells" in a layer of marine stratocumulus over the southeastern Pacific Ocean ... into interesting structures such as those shown here. These cells are notably small, with diameters ranging from 10-15 kilometers, instead ...

  10. Photometric Survey for Asynchronous Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Pravec, P.

    2005-05-01

    Asynchronous binary asteroids have been found to be abundant among fast- spinning near-Earth asteroids (NEAs) smaller than 2 km in diameter; Pravec et al. (2005, Icarus, submitted) derived that 15 +/- 4 % of NEAs in the size range 0.3 to 2 km are binary with the secondary-to-primary mean diameter ratio >=0.18. The early re-sults from the surveys of the Vesta family and the Hungaria group (Ryan et al., 2004, Planet. Space Sci. 42, 1093; 2004, Bull. Amer. Astron. Society 36, 1181; Warner et al., 2005, IAU Circ. 8511) suggest that the popula-tion extends beyond the region of terrestrial planets, but with characteristics shifted to larger sizes and longer periods; the four known binaries in the Vesta family/Hungaria group are 3 to 6 km large and they have primary rotation periods in a range of 3 to ~4 h, i.e., on the tail of the distribution of primary rotation periods of NEAs. The comparison suggests that formation and evolution mechanisms of asynchronous NEA and main-belt binaries may be similar and are related to their fast spins and rubble-pile structure. None of the current theories of their formation of evolution, however, explains the observed properties of both NEA and main- belt asynchronous bina-ries in full. We have established a collaborative observational program, called "Photometric Survey for Asynchro-nous Binary Asteroids" to discover and describe asynchronous binaries over a range of heliocentric distances from NEAs through Mars-crossers to inner main-belt asteroids. One new binary Amor asteroid, 2005 AB has been found during the first few months of the survey operation (Reddy et al., 2005, IAU Circ. 8483), and we have obtained follow-up data for two other binary systems. I outline the motivations, the technique, and the strategy of the Survey.

  11. Stability of a planet in the HD 41004 binary system

    NASA Astrophysics Data System (ADS)

    Satyal, S.; Musielak, Z. E.

    2016-03-01

    The Hill stability criterion is applied to analyse the stability of a planet in the binary star system of HD 41004 AB, with the primary and secondary separated by 22 AU, and masses of 0.7 M_⊙ and 0.4 M_⊙, respectively. The primary hosts one planet in an S-type orbit, and the secondary hosts a brown dwarf (18.64 M_J) on a relatively close orbit, 0.0177 AU, thereby forming another binary pair within this binary system. This star-brown dwarf pair (HD 41004 B+Bb) is considered a single body during our numerical calculations, while the dynamics of the planet around the primary, HD 41004 Ab, is studied in different phase-spaces. HD 41004 Ab is a 2.6 M_J planet orbiting at the distance of 1.7 AU with orbital eccentricity 0.39. For the purpose of this study, the system is reduced to a three-body problem and is solved numerically as the elliptic restricted three-body problem (ERTBP). The {Hill stability} function is used as a chaos indicator to configure and analyse the orbital stability of the planet, HD 41004 Ab. The indicator has been effective in measuring the planet's orbital perturbation due to the secondary star during its periastron passage. The calculated Hill stability time series of the planet for the coplanar case shows the stable and quasi-periodic orbits for at least ten million years. For the reduced ERTBP the stability of the system is also studied for different values of planet's orbital inclination with the binary plane. Also, by recording the planet's {ejection time} from the system or {collision time} with a star during the integration period, stability of the system is analysed in a bigger phase-space of the planet's orbital inclination, ≤ 90o, and its semimajor axis, 1.65-1.75 AU. Based on our analysis it is found that the system can maintain a stable configuration for the planet's orbital inclination as high as 65o relative to the binary plane. The results from the Hill stability criterion and the planet's dynamical lifetime map are found to be

  12. Orbital period variation study of massive Beta-Lyrae eclipsing binary IU Auriga

    NASA Astrophysics Data System (ADS)

    Yilan, Erkan; Bulut, İbrahim

    2016-07-01

    The system IU Aur is a semi-detached close binary system with an orbital period of 1.81 days, containing a massive star. The O-C diagram of this binary was analyzed with the least-squares method by using all available times of minima. We have found a periodic change of orbital period of IU Aur. This change has been explained by the gravitational effects of a third companion on the binay star. The orbit Parameters of the third body have been derived from the analysis of the O-C curve. The analysis indicates that the eclipsing binary revolves around a third-body with a mass of about M_{3}>10M_{⊙} in a highly eccentric orbit.

  13. Gamma-ray bursts as the death throes of massive binary stars

    NASA Technical Reports Server (NTRS)

    Narayan, Ramesh; Paczynski, Bohdan; Piran, Tsvi

    1992-01-01

    We propose that gamma-ray bursts are created in the mergers of double neutron star binaries and black hole neutron star binaries at cosmological distances. Two different processes provide the electromagnetic energy for the bursts: neutrino-antineutrino annihilation into electron-position pairs during the merger, and magnetic flares generated by the Parker instability in a postmerger differentially rotating disk. In both cases, an optically thick fireball of size less than or approximately equal to 100 km is initially created, which expands ultrarelativistically to large radii before radiating. The scenario is only qualitative at this time, but it eliminates many previous objections to the cosmological merger model. The strongest bursts should be found close to, but not at the centers of, galaxies at redshifts of order 0.1, and should be accompanied by bursts of gravitational radiation from the spiraling-in binary which could be detected by LIGO.

  14. UV and X-ray emission in the interacting binary U Cephei

    NASA Technical Reports Server (NTRS)

    Gimenez, A.; Guinan, E. F.; Gonzalez-Riestra, R.

    1993-01-01

    The active close binary U Cep has been monitored in the ultraviolet, using IUE, during 1.25 orbital cycles. The emission spectrum at the bottom of the primary total eclipse confirms earlier suggestions of an unexpected absence of the Hell 1640 A line. Stronger than expected emission in some other lines like NV, CII, CIV or AlIII, indicative of hot plasma, points out that some important differences still remain between the active components of RS CVn-type binaries and the mass-losing components of semidetached Algols. Simultaneous X-ray measurements, carried out with GINGA, indicated a low upper limit flux in the observed energy range (1 to 10 keV). A comparison with other binary systems or isolated stars is discussed in order to understand the obtained results.

  15. Inevitable self-similar topology of binary trees and their diverse hierarchical density

    NASA Astrophysics Data System (ADS)

    Paik, K.; Kumar, P.

    2007-11-01

    Self-similar topology, which can be characterized as power law size distribution, has been found in diverse tree networks ranging from river networks to taxonomic trees. In this study, we find that the statistical self-similar topology is an inevitable consequence of any full binary tree organization. We show this by coding a binary tree as a unique bifurcation string. This coding scheme allows us to investigate trees over the realm from deterministic to entirely random trees. To obtain partial random trees, partial random perturbation is added to the deterministic trees by an operator similar to that used in genetic algorithms. Our analysis shows that the hierarchical density of binary trees is more diverse than has been described in earlier studies. We find that the connectivity structure of river networks is far from strict self-similar trees. On the other hand, organization of some social networks is close to deterministic supercritical trees.

  16. Assembling the Largest, Most Distant Sample of Halo Wide Binaries for Galactic Structure and Dynamics

    NASA Astrophysics Data System (ADS)

    Coronado, J.; Chanamé, J.

    2015-10-01

    Samples of wide binaries (agtrsim \\ 100\\ AU) are a gold mine for Galactic studies. They have been used on a large list of applications in a diversity of fields. In the dynamical arena, wide binaries provided the first meaningful constraints on the mass and nature of disk dark matter and, more recently, they were used to close the remaining parameter space of MACHO-like halo dark matter not accessible to the micro-lensing campaigns. All these applications were possible when samples of these objects became large enough to not be dominated by random, chance alignments of two unrelated stars projected on the sky. Nevertheless, still today the largest available sample of the particularly valuable halo wide binaries free from selection biases, contains not much more than 100 systems, and conclusions on dark matter are very sensitive to this fact.

  17. Molecular dynamics simulation of nucleation in the binary mixture n-nonane/methane.

    PubMed

    Braun, Stephan; Kalikmanov, Vitaly; Kraska, Thomas

    2014-03-28

    Vapor-liquid nucleation in the binary system n-nonane/methane is investigated by molecular dynamics simulation. The supersaturation is achieved by cooling down the system during the expansion in order to closely mimic the real process. Binary clusters formed by nucleation are frequently inhomogeneous objects in which components are not well mixed. By studying high-pressure nucleation and cluster growth in the n-nonane/methane mixture, we demonstrate the role of structuring effects in these processes. At typical simulation conditions-pressure 60 bar, temperature 240 K, and nucleation rate ∼10(26) cm(-3)s(-1)-the mole fraction of methane in the critical cluster reaches 80 percent, which is much higher than its equilibrium value in the bulk liquid at the same pressure and temperature. These observations are supported by the recently formulated coarse-grained theory for binary nucleation as well as by the experimental observations. PMID:24697439

  18. The evolution of highly compact binary stellar systems in globular clusters

    NASA Technical Reports Server (NTRS)

    Krolik, J. H.; Meiksin, A.; Joss, P. C.

    1984-01-01

    A highly compact binary represents a system which is composed of a collapsed object (degenerate dwarf, neutron star, or black hole) in orbit with a low-mass (equal to or less than 0.5 solar mass) secondary star. Matter may be transferred from the secondary to the collapsed star due to the decay of the orbit resulting from the emission of gravitational radiation. The present investigation has the objective to study quantitatively the evolution of highly compact binaries in globular cluster cores, subject to the interplay of gravitational radiation and collisions with field stars. The investigation is exploratory in nature. The numerical methods employed are based on the techniques developed by Rappaport et al. (1982). It is found that occasional close encounters with field stars strongly dominate the evolution of highly compact binaries in dense globular cluster cores. Attention is given to the applicability of the findings to observations of X-ray sources and cataclysmic variables.

  19. Radio Detection of Neutron Star Binary Mergers

    NASA Astrophysics Data System (ADS)

    Bear, Brandon; Cardena, Brett; Dispoto, Dana; Papadopoulos, Joanna; Kavic, Michael; Simonetti, John

    2011-10-01

    Neutron star binary systems lose energy through gravitational radiation, and eventually merge. The gravitational radiation from the merger can be detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO). It is expected that a transient radio pulse will also be produced during the merger event. Detection of such radio transients would allow for LIGO to search for signals within constrained time periods. We calculate the LWA-1 detection rate of transient events from neutron star binary mergers. We calculate the detection rate of transient events from neutron star binary mergers for the Long Wavelength Array and the Eight-meter-wavelength Transient Array.

  20. Measuring the Masses of Ophiuchus Binaries

    NASA Astrophysics Data System (ADS)

    Schaefer, Gail

    2014-02-01

    Our goal is to measure dynamical masses of low-mass (<1 Msun) young (<5 Myr) binary components. We propose to continue mapping the orbits of young pairs using AO imaging. Combined with high-resolution spectroscopy, this will yield mass precisions of <5. This is important to validate and distinguish among theoretical calculations of young star evolution, which are most discrepant for low-mass stars. We target 22 binaries in Ophiuchus with unmapped orbits and 1 binary for which additional astrometry will yield precision values for its masses and distance. We request two half-nights, with LGS and NGS AO using NIRC2 on Keck II.

  1. Revised photometric elements of eight eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Mezzetti, M.; Predolin, F.; Giuricin, G.; Mardirossian, F.

    1980-10-01

    Photoelectric lightcurves of eight eclipsing binaries, known as detached systems, have been reanalysed by means of Wood's model in order to obtain homogeneous photometric elements. All binaries are confirmed to be detached. TU Cam, CW CMa, YZ Cas, CW Eri, CO Lac and EE Peg appear to be normal main-sequence (or near main-sequence) detached systems, but only the absolute elements of CO Lac are well-known. The detached binaries EK Cep and IQ Per are shown to be anomalous.

  2. Solidification phenomena of binary organic mixtures

    NASA Technical Reports Server (NTRS)

    Chang, K.

    1982-01-01

    The coalescence rates and motion of liquid bubbles in binary organic mixtures were studied. Several factors such as temperature gradient, composition gradient, interfacial tension, and densities of the two phases play important roles in separation of phases of immiscible liquids. An attempt was made to study the effect of initial compositions on separation rates of well-dispersed organic mixtures at different temperatures and, ultimately, on the homogeneity of solidification of the immiscible binary organic liquids. These organic mixtures serve as models for metallic pseudo binary systems under study. Two specific systems were investigated: ethyl salicylate - diethyl glycol and succinonitrile - water.

  3. The SDSS spectroscopic catalogue of white dwarf-main-sequence binaries: new identifications from DR 9-12

    NASA Astrophysics Data System (ADS)

    Rebassa-Mansergas, A.; Ren, J. J.; Parsons, S. G.; Gänsicke, B. T.; Schreiber, M. R.; García-Berro, E.; Liu, X.-W.; Koester, D.

    2016-06-01

    We present an updated version of the spectroscopic catalogue of white dwarf-main-sequence (WDMS) binaries from the Sloan Digital Sky Survey (SDSS). We identify 938 WDMS binaries within the data releases (DR) 9-12 of SDSS plus 40 objects from DR 1-8 that we missed in our previous works, 646 of which are new. The total number of spectroscopic SDSS WDMS binaries increases to 3294. This is by far the largest and most homogeneous sample of compact binaries currently available. We use a decomposition/fitting routine to derive the stellar parameters of all systems identified here (white dwarf effective temperatures, surface gravities and masses, and secondary star spectral types). The analysis of the corresponding stellar parameter distributions shows that the SDSS WDMS binary population is seriously affected by selection effects. We also measure the Na I λλ 8183.27, 8194.81 absorption doublet and H α emission radial velocities (RV) from all SDSS WDMS binary spectra identified in this work. 98 objects are found to display RV variations, 62 of which are new. The RV data are sufficient enough to estimate the orbital periods of three close binaries.

  4. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    SciTech Connect

    Haghighipour, Nader; Kaltenegger, Lisa

    2013-11-10

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

  5. Pulsars in binary systems: probing binary stellar evolution and general relativity.

    PubMed

    Stairs, Ingrid H

    2004-04-23

    Radio pulsars in binary orbits often have short millisecond spin periods as a result of mass transfer from their companion stars. They therefore act as very precise, stable, moving clocks that allow us to investigate a large set of otherwise inaccessible astrophysical problems. The orbital parameters derived from high-precision binary pulsar timing provide constraints on binary evolution, characteristics of the binary pulsar population, and the masses of neutron stars with different mass-transfer histories. These binary systems also test gravitational theories, setting strong limits on deviations from general relativity. Surveys for new pulsars yield new binary systems that increase our understanding of all these fields and may open up whole new areas of physics, as most spectacularly evidenced by the recent discovery of an extremely relativistic double-pulsar system.

  6. Pulsars in binary systems: probing binary stellar evolution and general relativity.

    PubMed

    Stairs, Ingrid H

    2004-04-23

    Radio pulsars in binary orbits often have short millisecond spin periods as a result of mass transfer from their companion stars. They therefore act as very precise, stable, moving clocks that allow us to investigate a large set of otherwise inaccessible astrophysical problems. The orbital parameters derived from high-precision binary pulsar timing provide constraints on binary evolution, characteristics of the binary pulsar population, and the masses of neutron stars with different mass-transfer histories. These binary systems also test gravitational theories, setting strong limits on deviations from general relativity. Surveys for new pulsars yield new binary systems that increase our understanding of all these fields and may open up whole new areas of physics, as most spectacularly evidenced by the recent discovery of an extremely relativistic double-pulsar system. PMID:15105492

  7. Study of the reconstruction of fractal structure of closed-cell aluminum foam and its thermal conductivity

    NASA Astrophysics Data System (ADS)

    Xia, Dehong; Guo, Shanshan; Ren, Ling

    2012-02-01

    Based on the characteristics of the internal structure of closed-cell aluminum foam, this paper attempts to illustrate the process of reconstructing the internal structures of closed-cell aluminum foam in Monte-Carlo method and the fractal characteristics of the reconstructed model. Furthermore, Binary Array Method is proposed by analyzing the reconstructed model and the thermal conductivity model of closed-cell aluminum foam is established. At the same time, the thermal conductivity of the foam materials with different porosity is calculated by Binary Array Method, and the calculated value coincides with the experimental results in the reference, which proves the correctness of these methods.

  8. Observations of Candidate Binary Asteroids in the Jovian Trojan and Hilda Populations

    NASA Astrophysics Data System (ADS)

    Sonnett, Sarah M.; Mainzer, Amy K.; Grav, Tommy; Masiero, Joseph R.; Bauer, James M.; Kramer, Emily A.

    2016-10-01

    Jovian Trojans (hereafter, Trojans) are asteroids in stable orbits at Jupiter's L4 and L5 Lagrange points, and Hilda asteroids are inwards of the Trojans in 3:2 mean-motion resonance with Jupiter. Due to their special dynamical properties, observationally constraining the formation location and dynamical histories of Trojans and HIldas offers key input for giant planet migration models. A fundamental parameter in assessing formation location is the bulk density - with low-density objects associated with an ice-rich formation environment in the outer solar system and high-density objects typically linked to the warmer inner solar system. Bulk density can only be directly measured during a close fly-by or by determining the mutual orbits of binary asteroid systems. With the aim of determining densities for a statistically significant sample of Trojans and Hildas, we are undertaking an observational campaign to confirm and characterize candidate binary asteroids published in Sonnett et al. (2015). These objects were flagged as binary candidates because their large NEOWISE brightness variations imply shapes so elongated that they are not likely explained by a singular equilibrium rubble pile and instead may be two elongated, gravitationally bound asteroids. We are obtaining densely sampled rotational light curves of these possible binaries to search for light curve features diagnostic of binarity and to determine the orbital properties of any confirmed binary systems by modeling the light curve. We present preliminary results from the follow-up campaign of these candidates, including estimates on the densities of objects that appear to be in binary systems and the binary fraction for Trojans and Hildas.

  9. The Planet in the HR 7162 Binary System Discovered by PHASES Astrometry

    NASA Astrophysics Data System (ADS)

    Muterspaugh, Matthew W.; Lane, B. F.; Konacki, M.; Burke, B. F.; Colavita, M. M.; Shao, M.; Hartkopf, W. I.; Boss, A. P.; O'Connell, J.; Fekel, F. C.; Wiktorowicz, S. J.

    2011-01-01

    The now-completed Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) used phase-referenced long-baseline interferometry to monitor 51 binary systems with 35 micro-arcsecond measurement precision, resulting in the high-confidence detection of a planet in the HR 7162 system. The 1.5 Jupiter mass planet is in a 2 AU orbit around one of the stars, whereas the binary itself has a separation of only 19 AU. Despite the close stellar companion, this configuration is expected to be stable, based on dynamic simulations. In the context of our solar system, this is analogous to a Jovian planet just outside of Mars' orbit, with a second star at the distance of Uranus. If this configuration were present during the period of planet formation, the complex gravitational environment created by the stars would seem to disrupt planet formation mechanisms that require long times to complete (thousands of years or more). While it is possible the arrangement resulted from the planet being formed in another environment (a single star or wider binary) after which the system reached its current state via dynamic interactions (star-planet exchange with a binary, or the binary orbit shrinking by interacting with a passing star), the frequency of such interactions is very low. Because the PHASES search only had the sensitivity to rule out Jovian mass companions in 11 of our 51 systems, yet one such system was found, the result indicates either extreme luck or that there is a high frequency of 20 AU binaries hosting planets. The latter interpretation is supported by previous detections of planets in 5-6 additional 20 AU binaries in other surveys (though with less control over the statistics for determining frequency of occurrence). Thus, there is observational support suggesting that a mechanism for rapid Jovian planet formation occurs in nature.

  10. THERMAL X-RAY EMISSION FROM THE SHOCKED STELLAR WIND OF PULSAR GAMMA-RAY BINARIES

    SciTech Connect

    Zabalza, V.; Paredes, J. M.; Bosch-Ramon, V.

    2011-12-10

    Gamma-ray-loud X-ray binaries are binary systems that show non-thermal broadband emission from radio to gamma rays. If the system comprises a massive star and a young non-accreting pulsar, their winds will collide producing broadband non-thermal emission, most likely originated in the shocked pulsar wind. Thermal X-ray emission is expected from the shocked stellar wind, but until now it has neither been detected nor studied in the context of gamma-ray binaries. We present a semi-analytic model of the thermal X-ray emission from the shocked stellar wind in pulsar gamma-ray binaries, and find that the thermal X-ray emission increases monotonically with the pulsar spin-down luminosity, reaching luminosities of the order of 10{sup 33} erg s{sup -1}. The lack of thermal features in the X-ray spectrum of gamma-ray binaries can then be used to constrain the properties of the pulsar and stellar winds. By fitting the observed X-ray spectra of gamma-ray binaries with a source model composed of an absorbed non-thermal power law and the computed thermal X-ray emission, we are able to derive upper limits on the spin-down luminosity of the putative pulsar. We applied this method to LS 5039, the only gamma-ray binary with a radial, powerful wind, and obtain an upper limit on the pulsar spin-down luminosity of {approx}6 Multiplication-Sign 10{sup 36} erg s{sup -1}. Given the energetic constraints from its high-energy gamma-ray emission, a non-thermal to spin-down luminosity ratio very close to unity may be required.

  11. Closed-loop anesthesia.

    PubMed

    LE Guen, Morgan; Liu, Ngai; Chazot, Thierry; Fischler, Marc

    2016-05-01

    Automated anesthesia which may offer to the physician time to control hemodynamic and to supervise neurological outcome and which may offer to the patient safety and quality was until recently consider as a holy grail. But this field of research is now increasing in every component of general anesthesia (hypnosis, nociception, neuromuscular blockade) and literature describes some successful algorithms - single or multi closed-loop controller. The aim of these devices is to control a predefined target and to continuously titrate anesthetics whatever the patients' co morbidities and surgical events to reach this target. Literature contains many randomized trials comparing manual and automated anesthesia and shows feasibility and safety of this system. Automation could quickly concern other aspects of anesthesia as fluid management and this review proposes an overview of closed-loop systems in anesthesia.

  12. Laterally closed lattice homomorphisms

    NASA Astrophysics Data System (ADS)

    Toumi, Mohamed Ali; Toumi, Nedra

    2006-12-01

    Let A and B be two Archimedean vector lattices and let be a lattice homomorphism. We call that T is laterally closed if T(D) is a maximal orthogonal system in the band generated by T(A) in B, for each maximal orthogonal system D of A. In this paper we prove that any laterally closed lattice homomorphism T of an Archimedean vector lattice A with universal completion Au into a universally complete vector lattice B can be extended to a lattice homomorphism of Au into B, which is an improvement of a result of M. Duhoux and M. Meyer [M. Duhoux and M. Meyer, Extended orthomorphisms and lateral completion of Archimedean Riesz spaces, Ann. Soc. Sci. Bruxelles 98 (1984) 3-18], who established it for the order continuous lattice homomorphism case. Moreover, if in addition Au and B are with point separating order duals (Au)' and B' respectively, then the laterally closedness property becomes a necessary and sufficient condition for any lattice homomorphism to have a similar extension to the whole Au. As an application, we give a new representation theorem for laterally closed d-algebras from which we infer the existence of d-algebra multiplications on the universal completions of d-algebras.

  13. DC CIRCUIT POWERED BY ORBITAL MOTION: MAGNETIC INTERACTIONS IN COMPACT OBJECT BINARIES AND EXOPLANETARY SYSTEMS

    SciTech Connect

    Lai Dong

    2012-09-20

    The unipolar induction DC circuit model, originally developed by Goldreich and Lynden-Bell for the Jupiter-Io system, has been applied to different types of binary systems in recent years. We show that there exists an upper limit to the magnetic interaction torque and energy dissipation rate in such a model. This arises because when the resistance of the circuit is too small, the large current flow severely twists the magnetic flux tube connecting the two binary components, leading to the breakdown of the circuit. Applying this limit, we find that in coalescing neutron star binaries, magnetic interactions produce negligible correction to the phase evolution of the gravitational waveform, even for magnetar-like field strengths. However, energy dissipation in the binary magnetosphere may still give rise to electromagnetic radiation prior to the final merger. For ultracompact white dwarf binaries, we find that unipolar induction does not provide adequate energy dissipation to explain the observed X-ray luminosities of several sources. For exoplanetary systems containing close-in Jupiters or super-Earths, the magnetic torque and energy dissipation induced by the orbital motion are negligible, except possibly during the early T Tauri phase, when the stellar magnetic field is stronger than 10{sup 3} G.

  14. Rotational Synchronization May Enhance Habitability for Circumbinary Planets: Kepler Binary Case Studies

    NASA Astrophysics Data System (ADS)

    Mason, Paul A.; Zuluaga, Jorge I.; Clark, Joni M.; Cuartas-Restrepo, Pablo A.

    2013-09-01

    We report a mechanism capable of reducing (or increasing) stellar activity in binary stars, thereby potentially enhancing (or destroying) circumbinary habitability. In single stars, stellar aggression toward planetary atmospheres causes mass-loss, which is especially detrimental for late-type stars, because habitable zones are very close and activity is long lasting. In binaries, tidal rotational breaking reduces magnetic activity, thus reducing harmful levels of X-ray and ultraviolet (XUV) radiation and stellar mass-loss that are able to erode planetary atmospheres. We study this mechanism for all confirmed circumbinary (p-type) planets. We find that main sequence twins provide minimal flux variation and in some cases improved environments if the stars rotationally synchronize within the first Gyr. Solar-like twins, like Kepler 34 and Kepler 35, provide low habitable zone XUV fluxes and stellar wind pressures. These wide, moist, habitable zones may potentially support multiple habitable planets. Solar-type stars with lower mass companions, like Kepler 47, allow for protected planets over a wide range of secondary masses and binary periods. Kepler 38 and related binaries are marginal cases. Kepler 64 and analogs have dramatically reduced stellar aggression due to synchronization of the primary, but are limited by the short lifetime. Kepler 16 appears to be inhospitable to planets due to extreme XUV flux. These results have important implications for estimates of the number of stellar systems containing habitable planets in the Galaxy and allow for the selection of binaries suitable for follow-up searches for habitable planets.

  15. ROTATIONAL SYNCHRONIZATION MAY ENHANCE HABITABILITY FOR CIRCUMBINARY PLANETS: KEPLER BINARY CASE STUDIES

    SciTech Connect

    Mason, Paul A.; Zuluaga, Jorge I.; Cuartas-Restrepo, Pablo A.; Clark, Joni M.

    2013-09-10

    We report a mechanism capable of reducing (or increasing) stellar activity in binary stars, thereby potentially enhancing (or destroying) circumbinary habitability. In single stars, stellar aggression toward planetary atmospheres causes mass-loss, which is especially detrimental for late-type stars, because habitable zones are very close and activity is long lasting. In binaries, tidal rotational breaking reduces magnetic activity, thus reducing harmful levels of X-ray and ultraviolet (XUV) radiation and stellar mass-loss that are able to erode planetary atmospheres. We study this mechanism for all confirmed circumbinary (p-type) planets. We find that main sequence twins provide minimal flux variation and in some cases improved environments if the stars rotationally synchronize within the first Gyr. Solar-like twins, like Kepler 34 and Kepler 35, provide low habitable zone XUV fluxes and stellar wind pressures. These wide, moist, habitable zones may potentially support multiple habitable planets. Solar-type stars with lower mass companions, like Kepler 47, allow for protected planets over a wide range of secondary masses and binary periods. Kepler 38 and related binaries are marginal cases. Kepler 64 and analogs have dramatically reduced stellar aggression due to synchronization of the primary, but are limited by the short lifetime. Kepler 16 appears to be inhospitable to planets due to extreme XUV flux. These results have important implications for estimates of the number of stellar systems containing habitable planets in the Galaxy and allow for the selection of binaries suitable for follow-up searches for habitable planets.

  16. Binaries in Star Clusters: A Photometric Approach with Application to the Hyades

    NASA Astrophysics Data System (ADS)

    El-Bassuny Alawy, A.; et al.

    The incidence and methods of identification of binaries in star clusters have been reviewed. A photometric approach is proposed in which stars are assumed to behave as black bodies and standard stellar multi-band photometric data are employed. The method is applicable to binaries of main sequence components but neither so wide as to be resolved nor very close so that mutual interaction is appreciable. The effects of stellar rotation on the colours were not considered. A theoretical Colour-Magnitude diagram is synthethised as well as tracks of binaries of different components and curves of iso-temperature ratio. The synthetic photometry has been adapted for and combined with photometry of the Hyades cluster to identify the cluster binaries. The agreement between the present results and those found by others is, within the limits of applicability of the method, almost exact. Moreover, it has been feasible to assign the spectral types of the components of a binary seen as a single star. The results obtained and discussions presented show that the approach proposed is, within the assumptions, extremely simple and highly reliable.

  17. Angular momentum transfer by gravitational torques and the evolution of binary protostars

    NASA Technical Reports Server (NTRS)

    Boss, A. P.

    1984-01-01

    The efficiency of angular momentum transport by gravitational torques is investigated semianalytically for two idealized models. The first model, a rotating ellipsoid embedded within another ellipsoid, is compared with numerical results for the fission instability of a radpidly-rotating polytrope. The fission instability is aborted by the rapid transfer of angular momentum outward by gravitational torques. The global rates of angular momentum transfer by gravitational torques in rotating gas clouds such as the presolar nebula are shown to be comparable to the rates assumed to be appropriate for transfer by turbulent stresses. The second model is a binary system embedded within a rotating ellipsoid. The binary orbital angular momentum decreases significantly when the phase angle with the ellipsoid is constant; the binary separation may then decrease by a factor of 100 within about an orbital period. For a variable phase angle, little secular loss of orbital angular momentum occurs. Binaries which form in the isothermal regime of the theory of hierarchical fragmentation will not undergo orbital decay, whereas very close binaries composed of nonisothermal fragments may decay and merge into single objects.

  18. Minima Times of Selected Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Parimucha, S.; Dubovsky, P.; Kudak, V.; Perig, V.

    2016-05-01

    We present 221 CCD minima times of the 76 selected eclipsing binaries obtained during 2013-2016 at Observatory at Kolonica Saddle in Slovakia and Observatory of Laboratory of Space Research, Uzhhorod National University in Ukraine

  19. X-ray reprocessing in binaries

    NASA Astrophysics Data System (ADS)

    Paul, Biswajit

    2016-07-01

    We will discuss several aspects of X-ray reprocessing into X-rays or longer wavelength radiation in different kinds of binary systems. In high mass X-ray binaries, reprocessing of hard X-rays into emission lines or lower temperature black body emission is a useful tool to investigate the reprocessing media like the stellar wind, clumpy structures in the wind, accretion disk or accretion stream. In low mass X-ray binaries, reprocessing from the surface of the companion star, the accretion disk, warps and other structures in the accretion disk produce signatures in longer wavelength radiation. X-ray sources with temporal structures like the X-ray pulsars and thermonuclear burst sources are key in such studies. We will discuss results from several new investigations of X-ray reprocessing phenomena in X-ray binaries.

  20. Selection effects and binary galaxy velocity differences

    NASA Technical Reports Server (NTRS)

    Schneider, Stephen E.; Salpeter, Edwin E.

    1990-01-01

    Measurements of the velocity differences (delta v's) in pairs of galaxies from large statistical samples have often been used to estimate the average masses of binary galaxies. A basic prediction of these models is that the delta v distribution ought to decline monotonically. However, some peculiar aspects of the kinematics have been uncovered, with an anomalous preference for delta v approx. equal to 72 km s(sup-1) appearing to be present in the data. The authors examine a large sample of binary galaxies with accurate redshift measurements and confirm that the distribution of delta v's appears to be non-monotonic with peaks at 0 and approx. 72 km s (exp -1). The authors suggest that the non-zero peak results from the isolation criteria employed in defining samples of binaries and that it indicates there are two populations of binary orbits contributing to the observed delta v distribution.

  1. ROTATIONAL DOPPLER BEAMING IN ECLIPSING BINARIES

    SciTech Connect

    Groot, Paul J.

    2012-01-20

    In eclipsing binaries the stellar rotation of the two components will cause a rotational Doppler beaming during eclipse ingress and egress when only part of the eclipsed component is covered. For eclipsing binaries with fast spinning components this photometric analog of the well-known spectroscopic Rossiter-McLaughlin effect can exceed the strength of the orbital effect. Example light curves are shown for a detached double white dwarf binary, a massive O-star binary and a transiting exoplanet case, similar to WASP-33b. Inclusion of the rotational Doppler beaming in eclipsing systems is a prerequisite for deriving the correct stellar parameters from fitting high-quality photometric light curves and can be used to determine stellar obliquities as well as, e.g., an independent measure of the rotational velocity in those systems that may be expected to be fully synchronized.

  2. Recent Minima of 171 Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

    Samolyk, G.

    2015-12-01

    This paper continues the publication of times of minima for 171 eclipsing binary stars from observations reported to the AAVSO EB section. Times of minima from observations received by the author from March 2015 thru October 2015 are presented.

  3. Dixie Valley Bottoming Binary Unit

    SciTech Connect

    McDonald, Dale

    2014-12-21

    This binary plant is the first air cooled, high-output refrigeration based waste heat recovery cycle in the industry. Its working fluid is environmentally friendly and as such, the permits that would be required with a hydrocarbon based cycle are not necessary. The unit is largely modularized, meaning that the unit’s individual skids were assembled in another location and were shipped via truck to the plant site. The Air Cooled Condensers (ACC), equipment piping, and Balance of Plant (BOP) piping were constructed at site. This project further demonstrates the technical feasibility of using low temperature brine for geothermal power utilization. The development of the unit led to the realization of low temperature, high output, and environmentally friendly heat recovery systems through domestic research and engineering. The project generates additional renewable energy, resulting in cleaner air and reduced carbon dioxide emissions. Royalty and tax payments to governmental agencies will increase, resulting in reduced financial pressure on local entities. The major components of the unit were sourced from American companies, resulting in increased economic activity throughout the country.

  4. The binary fission origin of the moon

    NASA Technical Reports Server (NTRS)

    Binder, Alan B.

    1986-01-01

    The major arguments for and against the binary fission model of lunar origin are reviewed. Unresolved problems include: (1) how the protoearth acquired sufficient angular velocity to fission, and (2) how the earth-moon system lost its excess angular momentum after fission. Despite these uncertainties, the compositional similarities between the earth's mantle and the bulk moon suggest that the fission model is worth considering. The proposed sequence of events in the formation of the moon by binary fission is given.

  5. Constraining Planet Formation in the Unique Evolved Binary HR 637 {GJ 86}

    NASA Astrophysics Data System (ADS)

    Farihi, Jay

    2011-10-01

    An intriguing characteristic of the known exoplanets is the existence of gas giants in moderately close binary systems. Among these planet-hosting binaries, the HR 637 {GJ 86} system is particularly interesting; the exoplanet GJ 86b executes a 0.1 AU orbit about an early K dwarf that is in turn bound to a white dwarf near 20 AU. The progenitor of GJ 86B was originally the more massive stellar component, orbiting near 12 AU until post-main sequence mass loss expanded its separation. This picture presents a gravitational challenge to planet formation at GJ86A: how does a giant planet form around a solar-mass star in such close proximity to an intermediate-mass star? Also, did GJ 86b form at the same epoch as the stars, or during the post-main sequence evolution of the secondary? To model the formation of GJ 86b, a knowledge of the current and primordial stellar masses and separations is required.We propose WFC3 imaging of this high-contrast, 2 arcsec binary in several bandpasses, and subsequent STIS optical spectroscopy of the white dwarf GJ 86B. The imaging is essential to determine the precise location of the companion for STIS spectroscopy, while the broad-band colors will yield the temperature of the white dwarf. The spectroscopy will reveal the atmospheric composition - including refractory pollutants - of the white dwarf, and together with its known parallax, determine its radius and mass, the mass of its progenitor, the original binary separation, and total system age. From these data, we will be able to strongly constrain planet formation scenarios in this relatively close binary, and potentially obtain evidence of terrestrial planets within the system.

  6. Spectroscopic Subsystems in Nearby Wide Binaries

    NASA Astrophysics Data System (ADS)

    Tokovinin, Andrei

    2015-12-01

    Radial velocity (RV) monitoring of solar-type visual binaries has been conducted at the CTIO/SMARTS 1.5 m telescope to study short-period systems. The data reduction is described, and mean and individual RVs of 163 observed objects are given. New spectroscopic binaries are discovered or suspected in 17 objects, and for some of them the orbital periods could be determined. Subsystems are efficiently detected even in a single observation by double lines and/or by the RV difference between the components of visual binaries. The potential of this detection technique is quantified by simulation and used for statistical assessment of 96 wide binaries within 67 pc. It is found that 43 binaries contain at least one subsystem, and the occurrence of subsystems is equally probable in either primary or secondary components. The frequency of subsystems and their periods matches the simple prescription proposed by the author. The remaining 53 simple wide binaries with a median projected separation of 1300 AU have an RV difference distribution between their components that is not compatible with the thermal eccentricity distribution f (e) = 2e but rather matches the uniform eccentricity distribution.

  7. Eclipsing Binary B-Star Mass Determinations

    NASA Astrophysics Data System (ADS)

    Townsend, Amanda; Eikenberry, Stephen S.

    2016-01-01

    B-stars in binary pairs provide a laboratory for key astrophysical measurements of massive stars, including key insights for the formation of compact objects (neutron stars and black holes). In their paper, Martayan et al (2004) find 23 Be binary star pairs in NGC2004 in the Large Magellanic Cloud, five of which are both eclipsing and spectroscopic binaries with archival data from VLT-Giraffe and photometric data from MACHO. By using the Wilson eclipsing binary code (e.g., Wilson, 1971), we can determine preliminary stellar masses of the binary components. We present the first results from this analysis. This study also serves as proof-of-concept for future observations with the Photonic Synthesis Telescope Array (Eikenberry et al., in prep) that we are currently building for low-cost, precision spectroscopic observations. With higher resolution and dedicated time for observations, we can follow-up observations of these Be stars as well as Be/X-ray binaries, for improved mass measurements of neutron stars and black holes and better constraints on their origin/formation.

  8. SPECTROSCOPIC SUBSYSTEMS IN NEARBY WIDE BINARIES

    SciTech Connect

    Tokovinin, Andrei

    2015-12-15

    Radial velocity (RV) monitoring of solar-type visual binaries has been conducted at the CTIO/SMARTS 1.5 m telescope to study short-period systems. The data reduction is described, and mean and individual RVs of 163 observed objects are given. New spectroscopic binaries are discovered or suspected in 17 objects, and for some of them the orbital periods could be determined. Subsystems are efficiently detected even in a single observation by double lines and/or by the RV difference between the components of visual binaries. The potential of this detection technique is quantified by simulation and used for statistical assessment of 96 wide binaries within 67 pc. It is found that 43 binaries contain at least one subsystem, and the occurrence of subsystems is equally probable in either primary or secondary components. The frequency of subsystems and their periods matches the simple prescription proposed by the author. The remaining 53 simple wide binaries with a median projected separation of 1300 AU have an RV difference distribution between their components that is not compatible with the thermal eccentricity distribution f (e) = 2e but rather matches the uniform eccentricity distribution.

  9. ORBITAL SOLUTIONS FOR TWO YOUNG, LOW-MASS SPECTROSCOPIC BINARIES IN OPHIUCHUS

    SciTech Connect

    Rosero, V.; Prato, L.; Wasserman, L. H.; Rodgers, B. E-mail: lprato@lowell.edu E-mail: brodgers@gemini.edu

    2011-01-15

    We report the orbital parameters for ROXR1 14 and RX J1622.7-2325Nw, two young, low-mass, and double-lined spectroscopic binaries recently discovered in the Ophiuchus star-forming region. Accurate orbital solutions were determined from over a dozen high-resolution spectra taken with the Keck II and Gemini South telescopes. These objects are T Tauri stars with mass ratios close to unity and periods of {approx}5 and {approx}3 days, respectively. In particular, RX J1622.7-2325Nw shows a non-circularized orbit with an eccentricity of 0.30, higher than any other short-period pre-main-sequence (PMS) spectroscopic binary known to date. We speculate that the orbit of RX J1622.7-2325Nw has not yet circularized because of the perturbing action of a {approx}1'' companion, itself a close visual pair. A comparison of known young spectroscopic binaries (SBs) and main-sequence (MS) SBs in the eccentricity-period plane shows an indistinguishable distribution of the two populations, implying that orbital circularization occurs in the first 1 Myr of a star's lifetime. With the results presented in this paper we increase by {approx}4% the small sample of PMS spectroscopic binary stars with known orbital elements.

  10. The discovery and characterisation of binary central stars in planetary nebulae

    NASA Astrophysics Data System (ADS)

    Jones, David

    2016-07-01

    Close binary central stars of planetary nebulae are key in constraining the poorly- understood common-envelope phase of evolution, which in turn is critical in understanding the formation of a wide-range of astrophysical phenomena (including cataclysmic variables, low-mass X-ray binaries and supernovae type Ia). Here, I present the results of our on-going, targeted search for close-binaries in planetary nebulae which has led to the discovery of more than ten new central binaries in just the last few years (almost the same as the total discovered during the 1980s and 1990s together). This success has been rooted in the targeted selection of objects for study, based on morphological features deemed typical of binarity, as well as novel observing strategies (including the employment of narrow-band filters for photometry to minimise nebular contamination), both of which are discussed. These new discoveries coupled with the painstaking characterisation of both newly discovered systems and those from the literature mean that we are now in a position to begin to probe the poorly understood common-envelope phase.

  11. Design and Implementation of BDB, the Binary Star Database

    NASA Astrophysics Data System (ADS)

    Kaygorodov, P.; Kovaleva, D.; Malkov, O.

    2013-02-01

    The Binary star DataBase (BDB, http://bdb.inasan.ru) is created to provide liasons between binary star catalogue data of various origin. Information on different observational types of binaries is obtained from heterogeneous sources of data - astronomical catalogues and surveys. The database allows a variety of query options useful for selected stars investigation purposes, for binary observations planning, and for construction and examination of binary datasets with certain characteristics.

  12. CLASSIFYING X-RAY BINARIES: A PROBABILISTIC APPROACH

    SciTech Connect

    Gopalan, Giri; Bornn, Luke; Vrtilek, Saeqa Dil

    2015-08-10

    In X-ray binary star systems consisting of a compact object that accretes material from an orbiting secondary star, there is no straightforward means to decide whether the compact object is a black hole or a neutron star. To assist in this process, we develop a Bayesian statistical model that makes use of the fact that X-ray binary systems appear to cluster based on their compact object type when viewed from a three-dimensional coordinate system derived from X-ray spectral data where the first coordinate is the ratio of counts in the mid- to low-energy band (color 1), the second coordinate is the ratio of counts in the high- to low-energy band (color 2), and the third coordinate is the sum of counts in all three bands. We use this model to estimate the probabilities of an X-ray binary system containing a black hole, non-pulsing neutron star, or pulsing neutron star. In particular, we utilize a latent variable model in which the latent variables follow a Gaussian process prior distribution, and hence we are able to induce the spatial correlation which we believe exists between systems of the same type. The utility of this approach is demonstrated by the accurate prediction of system types using Rossi X-ray Timing Explorer All Sky Monitor data, but it is not flawless. In particular, non-pulsing neutron systems containing “bursters” that are close to the boundary demarcating systems containing black holes tend to be classified as black hole systems. As a byproduct of our analyses, we provide the astronomer with the public R code which can be used to predict the compact object type of XRBs given training data.

  13. SELF-REGULATED SHOCKS IN MASSIVE STAR BINARY SYSTEMS

    SciTech Connect

    Parkin, E. R.; Sim, S. A. E-mail: s.sim@qub.ac.uk

    2013-04-20

    In an early-type, massive star binary system, X-ray bright shocks result from the powerful collision of stellar winds driven by radiation pressure on spectral line transitions. We examine the influence of the X-rays from the wind-wind collision shocks on the radiative driving of the stellar winds using steady-state models that include a parameterized line force with X-ray ionization dependence. Our primary result is that X-ray radiation from the shocks inhibits wind acceleration and can lead to a lower pre-shock velocity, and a correspondingly lower shocked plasma temperature, yet the intrinsic X-ray luminosity of the shocks, L{sub X}, remains largely unaltered, with the exception of a modest increase at small binary separations. Due to the feedback loop between the ionizing X-rays from the shocks and the wind driving, we term this scenario as self-regulated shocks. This effect is found to greatly increase the range of binary separations at which a wind-photosphere collision is likely to occur in systems where the momenta of the two winds are significantly different. Furthermore, the excessive levels of X-ray ionization close to the shocks completely suppress the line force, and we suggest that this may render radiative braking less effective. Comparisons of model results against observations reveal reasonable agreement in terms of log (L{sub X}/L{sub bol}). The inclusion of self-regulated shocks improves the match for kT values in roughly equal wind momenta systems, but there is a systematic offset for systems with unequal wind momenta (if considered to be a wind-photosphere collision).

  14. Rings from Close Encounters

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    Weve recently discovered narrow sets of rings around two minor planets orbiting in our solar system. How did these rings form? A new study shows that they could be a result of close encounters between the minor planets and giants like Jupiter or Neptune.Unexpected Ring SystemsPositions of the centaurs in our solar system (green). Giant planets (red), Jupiter trojans (grey), scattered disk objects (tan) and Kuiper belt objects (blue) are also shown. [WilyD]Centaurs are minor planets in our solar system that orbit between Jupiter and Neptune. These bodies of which there are roughly 44,000 with diameters larger than 1 km have dynamically unstable orbits that cross paths with those of one or more giant planets.Recent occultation observations of two centaurs, 10199 Chariklo and 2060 Chiron, revealed that these bodies both host narrow ring systems. Besides our four giant planets, Chariklo and Chiron are the only other bodies in the solar system known to have rings. But how did these rings form?Scientists have proposed several models, implicating collisions, disruption of a primordial satellite, or dusty outgassing. But a team of scientists led by Ryuki Hyodo (Paris Institute of Earth Physics, Kobe University) has recently proposed an alternative scenario: what if the rings were formed from partial disruption of the centaur itself, after it crossed just a little too close to a giant planet?Tidal Forces from a GiantHyodo and collaborators first used past studies of centaur orbits to estimate that roughly 10% of centaurs experience close encounters (passing within a distance of ~2x the planetary radius) with a giant planet during their million-year lifetime. The team then performed a series of simulations of close encounters between a giant planet and a differentiated centaur a body in which the rocky material has sunk to form a dense silicate core, surrounded by an icy mantle.Some snapshots of simulation outcomes (click for a closer look!) for different initial states of

  15. Navy closes Antarctic unit

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    After 42 years as a key participant in the United States Antarctic Program (USAP), the U.S. Navy held a ceremony on February 20 to commemorate the closing of its Naval Antarctic Support Unit stationed in New Zealand. The Navy originally had announced its decision to "disestablish" the unit in 1993, citing new global priorities with the end of the Cold War.The Navy will continue to provide limited flight support to the USAP through the end of the 1998-1999 austral research season.

  16. Be stars with white dwarf companions: a new single degenerate binary channel to type Ia supernovae explosions

    NASA Astrophysics Data System (ADS)

    Orio, Marina; Luna, Gerardo; Zemko, Polina; Kotulla, Ralf; Gallagher, Jay; Harbeck, Daniel

    2016-07-01

    A handful of supersoft X-ray sources in the Magellanic Clouds that could not be identified with transient nova outbursts turned out to be mainly massive close binaries. 6 years ago we suggested that several such sources may exist in M31, because we found that a certain fraction of supersoft sources was located in star forming regions. Following that discovery, we clearly identified a Be binary in M31, and are currently collecting data for another candidate in that galaxy. Work is in progress to assess whether the compact object companion really is a hydrogen burning white dwarf (the alternative being a massive stellar-mass black hole). If we can demonstrate that Be+white dwarf interacting close binaries are common, and that hydrogen is often ignited on the white dwarf in these systems, we have discovered a new promising channel towards the explosion of supernovae of type Ia in star forming regions, without invoking double degenerate systems.

  17. Stability and Coalescence of Massive Twin Binaries

    NASA Astrophysics Data System (ADS)

    Hwang, J.; Lombardi, J. C., Jr.; Rasio, F. A.; Kalogera, V.

    2015-06-01

    Massive stars are usually found in binaries, and binaries with periods less than 10 days may have a preference for near equal component masses (“twins”). In this paper we investigate the evolution of massive twin binaries all the way to contact and the possibility that these systems can be progenitors of double neutron star binaries. The small orbital separations of observed double neutron star binaries suggest that the progenitor systems underwent a common envelope phase at least once during their evolution. Bethe & Brown proposed that massive binary twins will undergo a common envelope evolution while both components are ascending the red giant branch (RGB) or asymptotic giant branch (AGB) simultaneously, also known as double-core evolution. Using models generated from the stellar evolution code EZ (evolve zero-age main sequence), we determine the range of mass ratios resulting in a contact binary with both components simultaneously ascending the RGB or AGB as a function of the difference in birth times, Δτ. We find that, even for a generous Δτ = 5 Myr, the minimum mass ratio {{q}min }=0.933 for an 8 {{M}⊙ } primary and increases for larger mass primaries. We use a smoothed particle hydrodynamics code, StarSmasher, to study specifically the evolution of q = 1 common envelope systems as a function of initial component mass, age, and orbital separation. We also consider a q = 0.997 system to test the effect of relaxing the constraint of strictly identical components. We find the dynamical stability limit, the largest orbital separation where the binary becomes dynamically unstable, as a function of the component mass and age. Finally, we calculate the efficiency of ejecting matter during the inspiral phase to extrapolate the properties of the remnant binary from our numerical results, assuming the common envelope is completely ejected. We find that for the nominal core masses, there is a minimum orbital separation for a given component mass such that the

  18. The Effects of Close Companions on the Magnetic Activity of M Dwarfs

    NASA Astrophysics Data System (ADS)

    Morgan, D. P.; West, A. A.; Silvestri, N. M.

    2011-12-01

    We present a study of close white dwarf and M dwarf (WD+dM) binary systems that examines the effects that close companions have on magnetic field generation in M dwarfs. We used a base sample of 1602 white dwarf -- main seqeuence (WDMS) binaries from Rebassa-Mansergas et al. to determine a set of color cuts in u, g, r, i, and z. Then using the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) we constructed a sample of 2292 WD+dM pairs. We separated the dM and WD from each combined spectrum using an iterative technique that compared the WD and dM components to best-fit templates. Using the absolute height above the Galactic Plane as a proxy for age, and the Hα emission line as an indicator for magnetic activity, we investigated the age-activity relation for our sample; spectral types ≤M5. Our results show that early-type M dwarfs in close binary systems have increased magnetic activity in both magnitude and duration compared to their field counterparts. However, we begin to see a transition at spectral type M5 (just past the onset of full convection in M dwarfs), where the magnitude and duration in close WD+dM binary systems become more comparable to that of the field M dwarfs.

  19. Binary pulsars as probes of neutron star birth

    NASA Astrophysics Data System (ADS)

    Wijers, R. A. M. J.; van Paradijs, J.; van den Heuvel, E. P. J.

    1992-07-01

    We discuss two issues in the physics of neutron stars and their progenitors. The first is whether a neutron star receives a velocity kick when it is formed in the supernova-explosion of a massive star, and if it does, what is the characteristic magnitude, v(0), thereof? The second concerns the fate of close massive binaries that consist of a helium star and a companion with a mass of order a solar mass. Whether the helium star explodes as a supernova, leaving a neutron star, or alternatively becomes a white dwarf, depends on its mass. The issue is which mass, m, of the helium star divides the two cases. We conclude that even though there are only four known 1913+16-type binary pulsars, the kick's magnitude can be constrained to some extent: v(0) is less than 400 km/. m alone cannot be constrained well, but a line can be drawn in the (m, v(0))-plane that separates the acceptable pairs of values from the unacceptable ones. We also suggest how more stringent, but also more model-dependent, constraints may be found by combining our method with results of other studies.

  20. Planet Formation around Binary Stars: Tatooine Made Easy

    NASA Astrophysics Data System (ADS)

    Bromley, Benjamin C.; Kenyon, Scott J.

    2015-06-01

    We examine characteristics of circumbinary orbits in the context of current planet formation scenarios. Analytical perturbation theory predicts the existence of nested circumbinary orbits that are generalizations of circular paths around a single star. These orbits have forced eccentric motion aligned with the binary as well as higher frequency oscillations, yet they do not cross, even in the presence of massive disks and perturbations from large planets. For this reason, dissipative gas and planetesimals can settle onto these “most circular” orbits, facilitating the growth of protoplanets. Outside a region close to the binary where orbits are generally unstable, circumbinary planets form in much the same way as their cousins around a single star. Here, we review the theory and confirm its predictions with a suite of representative simulations. We then consider the circumbinary planets discovered with NASA’s Kepler satellite. These Neptune- and Jupiter-size planets, or their planetesimal precursors, may have migrated inward to reach their observed orbits, since their current positions are outside of unstable zones caused by overlapping resonances. In situ formation without migration seems less likely, only because the surface density of the protoplanetary disks must be implausibly high. Otherwise, the circumbinary environment is friendly to planet formation, and we expect that many earth-like “Tatooines” will join the growing census of circumbinary planets.

  1. Are Planetary Nebulae in Globular Clusters a Binary Phenomenon?

    NASA Astrophysics Data System (ADS)

    Jacoby, George H.; De Marco, O.; Davies, J. E.; Harrington, J. P.; Bond, H. E.

    2014-01-01

    It is believed that PNe can only form in globular clusters if the progenitor had been a close binary. We test this hypothesis by re-measuring the masses of all four PN central stars in the Galactic globular clusters. We obtained HST imaging data in V, I, [OIII], and Hα for JaFu 1 in Pal 6, the only PN in a globular cluster without HST observations, to determine the central star magnitudes and colors, and to examine its nebular morphology. We also obtained deep [OIII] images of IRAS 18333-2357, the PN in M22, to improve its morphological classification. We combine these data with archival HST spectra and images for K648 (aka, Ps 1) in M15 and for JaFu 2 in NGC 6441 to estimate the central star masses for all four PN. We use post-AGB tracks to derive masses, after re-evaluating the distances and temperatures, and hence luminosities. Three of the stars have masses of ~0.55 Msun (uncertainties of 0.01-0.02), only slightly higher than the WD masses found in clusters 0.53 Msun) indicating that they may be descendants of single stars, but their morphology suggests otherwise. K648, though, has a mass ~0.58 Msun suggesting that mass augmentation has occurred, thereby arguing more strongly for a binary interaction in the evolutionary history of these stars.

  2. A multiwavelength study of the M dwarf binary YY Geminorum

    NASA Astrophysics Data System (ADS)

    Butler, C. J.; Erkan, N.; Budding, E.; Doyle, J. G.; Foing, B.; Bromage, G. E.; Kellett, B. J.; Frueh, M.; Huovelin, J.; Brown, A.; Neff, J. E.

    2015-02-01

    We review the results of the 1988 multiwavelength campaign on the late-type eclipsing binary YY Geminorum. Observations include: broad-band optical and near-infrared photometry, simultaneous optical and ultraviolet (IUE) spectroscopy, X-ray (Ginga) and radio (VLA) data. From models fitted to the optical light curves, fundamental physical parameters have been determined together with evidence for transient maculations (spots) located near quadrature longitudes and intermediate latitudes. Eclipses were observed at optical, ultraviolet and radio wavelengths. Significant drops in 6 cm radio emission near the phases of both primary and secondary eclipse indicate relatively compact radio emitting volumes that may lie between the binary components. IUE observations during secondary eclipse are indicative of a uniform chromosphere saturated with Mg II emission and an extended volume of Lyα emission. Profile fitting of high-dispersion Hα spectra confirms the chromospheric saturation and indicates significant Hα opacity to heights of a few per cent of the photospheric radius. There is evidence for an enhanced Hα emission region visible near phase 0.25-0.35 which may be associated with a large spot on the primary and with two small optical flares which were also observed at other wavelengths: one in microwave radiation and the other in X-rays. For both flares, LX/Lopt is consistent with energy release in closed magnetic structures.

  3. GIANT OUTBURSTS IN Be/X-RAY BINARIES

    SciTech Connect

    Martin, Rebecca G.; Nixon, Chris; Armitage, Philip J.; Lubow, Stephen H.; Price, Daniel J.

    2014-08-01

    Be/X-ray binary systems exhibit both periodic (Type I) X-ray outbursts and giant (Type II) outbursts, whose origins have remained elusive. We suggest that Type II X-ray outbursts occur when a highly misaligned decretion disk around the Be star becomes eccentric, allowing the compact object companion to capture a large amount of material at periastron. Using three-dimensional smoothed particle hydrodynamics simulations, we model the long-term evolution of a representative Be/X-ray binary system. We find that periodic (Type I) X-ray outbursts occur when the neutron star is close to periastron for all disk inclinations. Type II outbursts occur for large misalignment angles and are associated with eccentricity growth which occurs on a timescale of about 10 orbital periods. Mass capture from the eccentric decretion disk results in an accretion disk around the neutron star whose estimated viscous time is long enough to explain the extended duration of Type II outbursts. Previous studies suggested that the outbursts are caused by a warped disk but our results suggest that this is not sufficient; the disk must be both highly misaligned and eccentric to initiate a Type II accretion event.

  4. Blue Straggler-White Dwarf binaries in Galactic field

    NASA Astrophysics Data System (ADS)

    Ekanayake, Gemunu B.; Wilhelm, Ronald J.

    2016-01-01

    The mass transfer in close binaries has been identified as the most probable formation channel for field blue straggler stars (BSSs). The companions to these BSSs are white dwarf stars (WDs) and can be detected at ultraviolet (UV) wavelengths in the spectral energy distribution of the binary, if the mass transfer happened recently so that WD is young and hot.We chose a sample of 2,188 BSSs in the temperature range of 7,000 - 9000 K. and surface gravity, Log g > 3.8, using the Sloan Stellar Parameter Pipeline, from the Sloan Digital Sky Survey (SDSS).From this, a sub-sample of 80 UV excess field BSSs were identified using UV photometry from the Galaxy Evolution Explorer (GALEX). By using a chi-square minimization technique we fit the observed SED of these UVe-BSSs to set of combined BS+WD models to find the best fitting WD parameters. By considering our fitting results and the theoretical estimates of mass-temperature relation for BSSs , we find that the likely companions to our sample of UVe-BSSs are He WDs. This means that the most likely scenario of formation of these UVe-BSSs is mass transfer onto a normal main sequence star from a red giant star.

  5. Exploring the Birth of Binary Stars

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-08-01

    More than half of all stars are thought to be in binary or multiple star systems. But how do these systems form? The misaligned spins of some binary protostars might provide a clue.Two Formation ModelsIts hard to tell how multiple-star systems form, since these systems are difficult to observe in their early stages. But based on numerical simulations, there are two proposed models for the formation of stellar binaries:Turbulent fragmentationTurbulence within a single core leads to multiple dense clumps. These clumps independently collapse to form stars that orbit each other.Disk fragmentationGravitational instabilities in a massive accretion disk cause the formation of a smaller, secondary disk within the first, resulting in two stars that orbit each other.Log column density for one of the authors simulated binary systems, just after the formation of two protostars. Diamonds indicate the protostar positions. [Adapted from Offner et al. 2016]Outflows as CluesHow can we differentiate between these formation mechanisms? Led by Stella Offner (University of Massachusetts), a team of scientists has suggested that the key isto examine the alignment of the stars protostellar outflows jets that are often emitted from the poles of young, newly forming stars.Naively, wed expect that disk fragmentation would produce binary stars with common angular momentum. As the stars spins would be aligned, they would therefore also launch protostellar jets that were aligned with each other. Turbulent fragmentation, on the other hand, would cause the stars to have independent angular momentum. This would lead to randomly oriented spins, so the protostellar jets would be misaligned.Snapshots from the authors simulations. Left panel of each pair: column density; green arrows giveprotostellar spin directions. Right panel: synthetic observations produced from the simulations; cyan arrows giveprotostellar outflow directions. [Offner et al. 2016]Simulations of FragmentationIn order to better

  6. On angular momentum transfer in binary systems. [stellar orbital period change

    NASA Technical Reports Server (NTRS)

    Wilson, R. E.; Stothers, R.

    1975-01-01

    The maximum limit for the conversion of orbital angular momentum into rotational angular momentum of the mass-gaining component in a close binary system is derived. It is shown that this conversion process does not seriously affect the rate of orbital period change and can be neglected in computing the mass transfer rate. Integration of this limit over the entire accretion process results in a value for the maximum accumulated rotational angular momentum that is 3 to 4 times larger than that implied by the observed underluminosity of stars in such systems as Mu(1) Sco, V Pup, SX Aur, and V356 Sgr. It is suggested that shell stars and emission-line stars in binary systems may be produced when the core angular momentum is transferred into an envelope having a rotational angular momentum close to the maximum limit.-

  7. Observational Investigations on Contact Binaries in Multiple-star Systems and Star Clusters

    NASA Astrophysics Data System (ADS)

    Liu, L.

    2013-01-01

    The W UMa-type contact binaries are strongly interacting systems whose components both fill their critical Roche lobes and share a convective common envelope. The models of contact binaries are bottlenecked due to too many uncertain parameters. In the 1960s and 1970s, the common convective envelope model was accepted after several fierce controversies. And then, the thermal relaxation oscillation (TRO) model, the discontinuity model, and the angular momentum loss (AML) model appeared. However, in the past forty years, there lacked remarkable advance. The coexistence of many unknown parameters blocks the theoretical development of contact binaries. A study on the contact binaries in multiple star systems and star clusters, which could provide lots of information for their formation and evolution, may be a potential growing point for understanding these objects. More and more evidence shows that many of contact binaries are located in multiple star systems and star clusters. In this thesis, we observed and analyzed contact binaries in the forementioned systems. The observational and theoretical studies for contact binary are also summarized briefly. The results obtained are as follows: (1) Three contact binaries V1128 Tau, GZ And, VW Boo which possess visual companions show periodic oscillations. The period ranges from 16.7 years to 46.5 years. These oscillations probably come from the orbital movement of a close third body. (2) Four contact binaries GSC 02393-00680, V396 Mon, FU Dra, SS Ari which do not have visual companions also present periodic oscillations. Whether they are real members of multiple star systems needs further investigations. These oscillations probably result from the orbital movement of a close M-type companion. (3) The periods of three contact binaries EQ Cep, ER Cep and V371 Cep in the old open cluster NGC 188 show a long-term increase. There is a cyclic period oscillation in ER Cep, with a period of 5.4 years. We find that the total mass of

  8. Birth of Massive Black Hole Binaries

    SciTech Connect

    Colpi, M.; Dotti, M.; Mayer, L.; Kazantzidis, S.; /KIPAC, Menlo Park

    2007-11-19

    If massive black holes (BHs) are ubiquitous in galaxies and galaxies experience multiple mergers during their cosmic assembly, then BH binaries should be common albeit temporary features of most galactic bulges. Observationally, the paucity of active BH pairs points toward binary lifetimes far shorter than the Hubble time, indicating rapid inspiral of the BHs down to the domain where gravitational waves lead to their coalescence. Here, we review a series of studies on the dynamics of massive BHs in gas-rich galaxy mergers that underscore the vital role played by a cool, gaseous component in promoting the rapid formation of the BH binary. The BH binary is found to reside at the center of a massive self-gravitating nuclear disc resulting from the collision of the two gaseous discs present in the mother galaxies. Hardening by gravitational torques against gas in this grand disc is found to continue down to sub-parsec scales. The eccentricity decreases with time to zero and when the binary is circular, accretion sets in around the two BHs. When this occurs, each BH is endowed with it own small-size ({approx}< 0.01 pc) accretion disc comprising a few percent of the BH mass. Double AGN activity is expected to occur on an estimated timescale of {approx}< 1 Myr. The double nuclear point-like sources that may appear have typical separation of {approx}< 10 pc, and are likely to be embedded in the still ongoing starburst. We note that a potential threat of binary stalling, in a gaseous environment, may come from radiation and/or mechanical energy injections by the BHs. Only short-lived or sub-Eddington accretion episodes can guarantee the persistence of a dense cool gas structure around the binary necessary for continuing BH inspiral.

  9. A Search for Fine Wines: Discovering Close Red Dwarf-White Dwarf Binaries

    NASA Astrophysics Data System (ADS)

    Boyd, Mark; Finch, C. T.; Hambly, N. C.; Henry, T. J.; Jao, W.; Riedel, A. R.; Subasavage, J. P.; Winters, J. G.; RECONS

    2012-01-01

    Like fine wines, stars come in both red and white varieties. Here we present initial results of the Fine Wines Project that targets red dwarf-white dwarf pairs. The two scientific goals of Fine Wines are (1) to develop methods to estimate ages for red dwarfs based on the cooling ages of the white dwarfs, and (2) to identify suitable pairs for dynamical mass determinations of white dwarfs to probe their interior structures. Here we focus on the search for Fine Wines, including sample selection, elimination of false positives, and initial reconnaissance. The sample was extracted via color-color plots from a pool of more than 30,000 proper motion systems examined during the SuperCOSMOS-RECONS (SCR) and UCAC3 Proper Motion (UPM) surveys. The initial sample of 75 best candidates is being observed for BVRI photometry and 3500-9500 A spectroscopy to confirm whether or not the systems are red dwarf-white dwarf pairs. Early results indicate that roughly 50% of the candidates selected are indeed Fine Wine systems. This effort is supported by the NSF through grant AST 09-08402 and via observations made possible by the SMARTS Consortium.

  10. Numerical improvements in the treatment of irradiated atmospheres in close binary systems

    NASA Astrophysics Data System (ADS)

    Claret, A.

    2005-11-01

    The irradiation of cool stellar atmospheres is reanalyzed using a modified version of the UMA (Uppsala Model Atmosphere) code which incorporates two improvements concerning 1) the spatial resolution (18 μ points instead of only 6 adopted previously) and 2) the adoption of modern atmosphere models to simulate hot companions. The implementation of a better spacial resolution is shown to be essential to describe with better accuracy the center to limb variation of the specific intensities. It is also shown that only by adopting such a resolution (or a higher one) it is possible to detect and quantify the limb-brightening with confidence. As in the case of standard (non-irradiated) plane-parallel models, the Least-Squares Method (LSM) applied to the series expansion for the specific intensity introduced by Claret (2000) is shown to be the best procedure to derive the limb-darkening coefficients for illuminated atmospheres producing very small scattering and conserving the flux accurately.

  11. On the irradiated stellar atmospheres in close binary systems: Improvements and uncertainties

    NASA Astrophysics Data System (ADS)

    Claret, A.

    2004-08-01

    The irradiation of cool stellar atmospheres is reanalyzed using a modified version of the UMA (Uppsala Model Atmosphere) code which incorporates two improvements concerning 1) the spacial resolution (18 μ points instead of only 6 adopted previously) and 2) adopting modern atmosphere models to simulate hot companions. The implementation of a better spacial resolution is shown to be essential to describe with accuracy the center to limb variation of the specific intensities. It is also shown that only by adopting such a resolution (or a higher one) it is possible to detected and quantify the limb-brightening with confidence. As in the case of standard (non-irradiated) plane-parallel models, the Least-Squares method applied to the series expansion for the specific intensity introduced by Claret (\\cite{Claret00}) is shown to be the best procedure to derive the limb-darkening coefficients for illuminated atmospheres producing very small scattering and conserving the flux accurately. Since UMA does not work for wavelengths shorter than 1500 Å, the introduction of hot models to simulate the external fluxes introduces severe uncertainties in the model of irradiation. These uncertainties were ignored in previous works using the same code and similar conditions of irradiation. Other limitations of the model of irradiation, such as the suitability of applying the spherical symmetry instead of the plane-parallel approximation, are also discussed.

  12. ULTRA-STRIPPED TYPE Ic SUPERNOVAE FROM CLOSE BINARY EVOLUTION

    SciTech Connect

    Tauris, T. M.; Langer, N.; Moriya, T. J.; Podsiadlowski, Ph.; Yoon, S.-C.; Blinnikov, S. I.

    2013-12-01

    Recent discoveries of weak and fast optical transients raise the question of their origin. We investigate the minimum ejecta mass associated with core-collapse supernovae (SNe) of Type Ic. We show that mass transfer from a helium star to a compact companion can produce an ultra-stripped core which undergoes iron core collapse and leads to an extremely fast and faint SN Ic. In this Letter, a detailed example is presented in which the pre-SN stellar mass is barely above the Chandrasekhar limit, resulting in the ejection of only ∼0.05-0.20 M {sub ☉} of material and the formation of a low-mass neutron star (NS). We compute synthetic light curves of this case and demonstrate that SN 2005ek could be explained by our model. We estimate that the fraction of such ultra-stripped to all SNe could be as high as 10{sup –3}-10{sup –2}. Finally, we argue that the second explosion in some double NS systems (for example, the double pulsar PSR J0737–3039B) was likely associated with an ultra-stripped SN Ic.

  13. Closing the loop.

    PubMed

    Dassau, E; Atlas, E; Phillip, M

    2011-02-01

    Closed-loop algorithms can be found in every aspect of everyday modern life. Automation and control are used constantly to provide safety and to improve quality of life. Closed-loop systems and algorithms can be found in home appliances, automobiles, aviation and more. Can one imagine nowadays driving a car without ABS, cruise control or even anti-sliding control? Similar principles of automation and control can be used in the management of diabetes mellitus (DM). The idea of an algorithmic/technological way to control glycaemia is not new and has been researched for more than four decades. However, recent improvements in both glucose-sensing technology and insulin delivery together with advanced control and systems engineering made this dream of an artificial pancreas possible. The artificial pancreas may be the next big step in the treatment of DM since the use of insulin analogues. An artificial pancreas can be described as internal or external devices that use continuous glucose measurements to automatically manage exogenous insulin delivery with or without other hormones in an attempt to restore glucose regulation in individuals with DM using a control algorithm. This device as described can be internal or external; can use different types of control algorithms with bi-hormonal or uni-hormonal design; and can utilise different ways to administer them. The different designs and implementations have transitioned recently from in silico simulations to clinical evaluation stage with practical applications in mind. This may mark the beginning of a new era in diabetes management with the introduction of semi-closed-loop systems that can prevent or minimise nocturnal hypoglycaemia, to hybrid systems that will manage blood glucose (BG) levels with minimal user intervention to finally fully automated systems that will take the user out of the loop. More and more clinical trials will be needed for the artificial pancreas to become a reality but initial encouraging

  14. FUV Spectroscopy of the sdOB Primary of the Eclipsing Binary System AA Dor

    NASA Astrophysics Data System (ADS)

    Fleig, J.; Rauch, T.; Werner, K.; Kruk, J. W.

    AADor is an eclipsing, close, post common-envelope binary (PCEB). We present a detailed spectral analysis of its sdOB primary based on observations obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). Due to a strong contamination by interstellar absorption, we had to model both, the stellar spectrum as well as the interstellar line absorption in order to reproduce the FUV observation well and to determine the photospheric parameters precisely.

  15. Importance of the specific heat anomaly in the design of binary Rankine cycle power plants

    SciTech Connect

    Pope, W.L.; Doyle, P.A.; Fulton, R.L.; Silvester, L.F.

    1980-05-01

    The transposed critical temperature (TPCT) is shown to be an extremely important thermodynamic property in the selection of working fluids and turbine states for geothermal power plants operating on a closed organic (binary) Rankine cycle. When the optimum working fluid composition and process states are determined for specified source and sink conditions, turbine inlet states consistently lie adjacent to the working fluids' TPCT line for all resource temperatures, constraints, and cost and efficiency factors investigated.

  16. NEAs' Satellites Under Close Encounters with Earth

    NASA Astrophysics Data System (ADS)

    Araujo, Rosana; Winter, O. C.

    2012-10-01

    In the present work we took into account the gravitational effects experienced by a NEA (Near-Earth Asteroid), during a close encounter with Earth, in order to estimate the stability regions of NEAs' satellites as a function of the encounter conditions and for different primary-satellite mass ratio values. Initially, the methodology consisted on numerically simulating a system composed by the Sun, the planets of the Solar System, and samples of NEAs belonging to the groups Apollo, Atens and Amor, for a period of 10 Myr. All encounters with Earth closer than 100 Earth's radius were registered. The next step consisted on simulating all those registered close encounters considering the Earth, the asteroid that perform the close encounter, and a cloud of satellites around the asteroid. We considered no-interacting satellites with circular orbits, random values for the inclination, longitude of the ascending node and true anomaly, and with radial distribution going from 0.024 to 0.4 Hill's radius of the asteroid. The largest radial distance for which all the satellites survive (no collision or ejection) is defined as the critical radius. We present a statistical analysis of the registered encounters and the critical radius found, defining the stable regions as a function of the impact parameter - d, and of the relative velocity - V. For the case of massless satellites, we found that all satellites survived for encounters with d>0.3 Earth Hill's radius. For impact parameter d<0.13 Earth Hill's radius, we found that particles with radial distance greater than 0.24 Hill's radius of the asteroid, are unstable, for any relative velocity. The results for the other considered cases will be presented and discussed. We also discuss the implications of the regions found, specially in the NEAs-binary scenarios.

  17. Active Inference for Binary Symmetric Hidden Markov Models

    NASA Astrophysics Data System (ADS)

    Allahverdyan, Armen E.; Galstyan, Aram

    2015-10-01

    We consider active maximum a posteriori (MAP) inference problem for hidden Markov models (HMM), where, given an initial MAP estimate of the hidden sequence, we select to label certain states in the sequence to improve the estimation accuracy of the remaining states. We focus on the binary symmetric HMM, and employ its known mapping to 1d Ising model in random fields. From the statistical physics viewpoint, the active MAP inference problem reduces to analyzing the ground state of the 1d Ising model under modified external fields. We develop an analytical approach and obtain a closed form solution that relates the expected error reduction to model parameters under the specified active inference scheme. We then use this solution to determine most optimal active inference scheme in terms of error reduction, and examine the relation of those schemes to heuristic principles of uncertainty reduction and solution unicity.

  18. The Challenge of Observing the Zeta Aurigae Binary Stars

    NASA Astrophysics Data System (ADS)

    Melillo, Frank J.

    2013-07-01

    This author, in Holtsville, NY, has contributed to the observations of the Zeta Auriga binary stars, which included Zeta Aurigae itself and 32 Cygni. Both Zeta Aur and 32 Cygni were monitored in V and B bands during the most recent eclipses in the fall of 2011 and in late summer 2012, respectively. In addition, some spectra of both stars were captured to monitor the brightness in the near-UV section, that traces the hot companion being eclipsed. The lightcurves of both Zeta Aurigae and 32 Cygni show precise timing during the entire recent eclipses. The magnitude and duration of the eclipses in photometric V and B bands are described here, and forecasts made for future eclipses. This poster represents the work by Frank J Melillo and the observations were spaced closely enough to generate the true shape of the V and B lightcurves.

  19. A multi-tiered wavefront sensor using binary optics

    SciTech Connect

    Neal, D.R.; Warren, M.E.; Gruetzner, J.K.; Smith, T.G.; Rosenthal, R.R.; McKechnie, T.S.

    1994-05-01

    Wavefront sensors have been used to make measurements in fluid- dynamics and for closed loop control of adaptive optics. In most common Shack-Hartmann wavefront wavefront sensors, the light is broken up into series of rectangular or hexagonal apertures that divide the light into a series of focal spots. The position of these focal spots is used to determine the wavefront slopes over each subaperture. Using binary optics technology, we have developed a hierarchical or fractal wavefront sensor that divides the subapertures up on a more optimal fashion. We have demonstrated this concept for up to four tiers and developed the wavefront reconstruction methods for both segmented adaptive optics and continous wavefront measurement.

  20. Lossless grey image compression using a splitting binary tree

    NASA Astrophysics Data System (ADS)

    Li, Tao; Tian, Xin; Xiong, Cheng-Yi; Li, Yan-Sheng; Zhang, Yun; Tian, Jin-Wen

    2013-10-01

    A multi-layer coding algorithm is proposed for grey image lossless compression. We transform the original image by a set of bases (e.g., wavelets, DCT, and gradient spaces). Then, the transformed image is split into a sub-image set with a binary tree. The set include two parts: major sub-images and minor sub-images, which are coded separately. Experimental results over a common dataset show that the proposed algorithm performs close to JPEG-LS in terms of bitrate. However, we can get a scalable image quality, which is similar to JPEG2000. A suboptimal compressed image can be obtained when the bitstream is truncated by unexpected factors. Our algorithm is quit suitable for image transmission, on internet or on satellites.

  1. Spinning compact binary inspiral. II. Conservative angular dynamics

    SciTech Connect

    Gergely, Laszlo Arpad

    2010-11-15

    We establish the evolution equations of the set of independent variables characterizing the 2PN rigorous conservative dynamics of a spinning compact binary, with the inclusion of the leading order spin-orbit, spin-spin, and mass quadrupole-mass monopole effects, for generic (noncircular, nonspherical) orbits. More specifically, we give a closed system of first order ordinary differential equations for the orbital elements of the osculating ellipse and for the angles characterizing the spin orientations with respect to the osculating orbit. We also prove that (i) the relative angle of the spins stays constant for equal mass black holes, irrespective of their orientation, and (ii) the special configuration of equal mass black holes with equal, but antialigned spins, both laying in the plane of motion (leading to the largest recoil found in numerical simulations) is preserved at 2PN level of accuracy, with leading order spin-orbit, spin-spin, and mass quadrupolar contributions included.

  2. Turbidity of a binary fluid mixture: Determining eta

    NASA Technical Reports Server (NTRS)

    Jacobs, Donald T.

    1994-01-01

    A ground based (1-g) experiment is in progress that will measure the turbidity of a density-matched, binary fluid mixture extremely close to the critical point. By covering the range of reduced temperatures t is equivalent to (T-T(sub c))/T(sub c) from 10(exp -8) to 10(exp -2), the turbidity measurements will allow the critical exponent eta to be determined. No experiment has determined a value of the critical exponent eta, yet its value is significant to theorists in critical phenomena. Interpreting the turbidity correctly is important if future NASA flight experiments use turbidity as an indirect measurement of relative temperature in shuttle experiments on critical phenomena in fluids.

  3. Turbidity of a Binary Fluid Mixture: Determining Eta

    NASA Technical Reports Server (NTRS)

    Jacobs, Donald T.

    1996-01-01

    A ground based (1-g) experiment is in progress that will measure the turbidity of a density-matched, binary fluid mixture extremely close to its liquid-liquid critical point. By covering the range of reduced temperatures t equivalent to (T-T(sub c)) / T(sub c) from 10(exp -8) to 10(exp -2), the turbidity measurements will allow the critical exponent eta to be determined. No experiment has precisely determined a value of the critical exponent eta, yet its value is significant to theorists in critical phenomena. Relatively simple critical phenomena, as in the liquid-liquid system studied here, serve as model systems for more complex systems near a critical point.

  4. New spectroscopic binary companions of giant stars and updated metallicity distribution for binary systems

    NASA Astrophysics Data System (ADS)

    Bluhm, P.; Jones, M. I.; Vanzi, L.; Soto, M. G.; Vos, J.; Wittenmyer, R. A.; Drass, H.; Jenkins, J. S.; Olivares, F.; Mennickent, R. E.; Vučković, M.; Rojo, P.; Melo, C. H. F.

    2016-10-01

    We report the discovery of 24 spectroscopic binary companions to giant stars. We fully constrain the orbital solution for 6 of these systems. We cannot unambiguously derive the orbital elements for the remaining stars because the phase coverage is incomplete. Of these stars, 6 present radial velocity trends that are compatible with long-period brown dwarf companions. The orbital solutions of the 24 binary systems indicate that these giant binary systems have a wide range in orbital periods, eccentricities, and companion masses. For the binaries with restricted orbital solutions, we find a range of orbital periods of between ~97-1600 days and eccentricities of between ~0.1-0.4. In addition, we studied the metallicity distribution of single and binary giant stars. We computed the metallicity of a total of 395 evolved stars, 59 of wich are in binary systems. We find a flat distribution for these binary stars and therefore conclude that stellar binary systems, and potentially brown dwarfs, have a different formation mechanism than planets. This result is confirmed by recent works showing that extrasolar planets orbiting giants are more frequent around metal-rich stars. Finally, we investigate the eccentricity as a function of the orbital period. We analyzed a total of 130 spectroscopic binaries, including those presented here and systems from the literature. We find that most of the binary stars with periods ≲30 days have circular orbits, while at longer orbital periods we observe a wide spread in their eccentricities. Based on observations collected at La Silla - Paranal Observatory under programs IDs IDs 085.C-0557, 087.C.0476, 089.C-0524, 090.C-0345, 096.A-9020 and through the Chilean Telescope Time under programs IDs CN2012A-73, CN2012B-47, CN2013A-111, CN2013B-51, CN2014A-52 and CN2015A-48.

  5. Binary star systems and extrasolar planets

    NASA Astrophysics Data System (ADS)

    Muterspaugh, Matthew Ward

    For ten years, planets around stars similar to the Sun have been discovered, confirmed, and their properties studied. Planets have been found in a variety of environments previously thought impossible. The results have revolutionized the way in which scientists understand planet and star formation and evolution, and provide context for the roles of the Earth and our own solar system. Over half of star systems contain more than one stellar component. Despite this, binary stars have often been avoided by programs searching for planets. Discovery of giant planets in compact binary systems would indirectly probe the timescales of planet formation, an important quantity in determining by which processes planets form. A new observing method has been developed to perform very high precision differential astrometry on bright binary stars with separations in the range of [approximate] 0.1--1.0 arcseconds. Typical measurement precisions over an hour of integration are on the order of 10 micro-arcseconds (mas), enabling one to look for perturbations to the Keplerian orbit that would indicate the presence of additional components to the system. This method is used as the basis for a new program to find extrasolar planets. The Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES) is a search for giant planets orbiting either star in 50 binary systems. The goal of this search is to detect or rule out planets in the systems observed and thus place limits on any enhancements of planet formation in binaries. It is also used to measure fundamental properties of the stars comprising the binary, such as masses and distances, useful for constraining stellar models at the 10 -3 level. This method of differential astrometry is applied to three star systems. d Equulei is among the most well-studied nearby binary star systems. Results of its observation have been applied to a wide range of fundamental studies of binary systems and stellar astrophysics. PHASES data are

  6. The chromospherically active binary CFTuc revisited

    NASA Astrophysics Data System (ADS)

    Doǧru, D.; Erdem, A.; Doǧru, S. S.; Zola, S.

    2009-08-01

    This paper presents results derived from analysis of new spectroscopic and photometric observations of the chromospherically active binary system CFTuc. New high-resolution spectra, taken at the Mt. John University Observatory in 2007, were analysed using two methods: cross-correlation and Fourier-based disentangling. As a result, new radial velocity curves of both components were obtained. The resulting orbital elements of CFTuc are a1 sini = 0.0254 +/- 0.0001au, a2sini = 0.0228 +/- 0.0001au, M1sini = 0.902 +/- 0.005Msolar and M2sini = 1.008 +/- 0.006Msolar. The cooler component of the system shows Hα and CaII H&K emissions. Using simultaneous spectroscopic and photometric observations, an anticorrelation between the Hα emission and the BV light curve maculation effects was found. This behaviour indicates a close spatial association between photospheric and chromospheric active regions. Our spectroscopic data and recent BV light curves were solved simultaneously using the Wilson-Devinney code. A dark spot on the surface of the cooler component was assumed to explain large asymmetries observed in the light curves. The following absolute parameters of the components were determined: M1 = 1.11 +/- 0.01Msolar, M2 = 1.23 +/- 0.01Msolar, R1 = 1.63 +/- 0.02Rsolar, R2 = 3.60 +/- 0.02Rsolar, L1 = 3.32 +/- 0.51Lsolar and L2 = 3.91 +/- 0.84Lsolar. The primary component has an age of about 5Gyr and is approaching its main-sequence terminal age. The distance to CFTuc was calculated to be 89 +/- 6pc from the dynamic parallax, neglecting interstellar absorption, in agreement with the Hipparcos value. The orbital period of the system was studied using the O-C analysis. The O-C diagram could be interpreted in terms of either two abrupt changes or a quasi-sinusoidal form superimposed on a downward parabola. These variations are discussed by reference to the combined effect of mass transfer and mass loss, the Applegate mechanism and also a light-time effect due to the existence of

  7. Nucleation in a Sheared Liquid Binary Mixture.

    NASA Astrophysics Data System (ADS)

    Min, Kyung-Yang

    When a binary liquid mixture of lutidine plus water (LW) is quenched to a temperature T and is exposed to a continuous shear rate S, the result is a steady-state droplet distribution. This steady state can be probed by measuring the unscattered intensity I_{f}, or the scattered intensity I_{s}, as a function of delta T and S. In the experiments described here, S is fixed and delta T is varied in a step-wise fashion. The absence of hysteresis was probed in two separate experiments: First, I_{f} was measured as a function of S for a given delta T. Next, I_{f} was measured as a function of delta T for a given S. In either case, the hysteresis associated with the shear-free nucleation is absent. In addition, a flow-history dependent hysteresis was studied. In the 2-dimensional parameter space consisting of S and delta T, the onset of nucleation uniquely determines a cloud point line. A plot of the cloud point line exhibits two segments of different slopes with a cross-over near the temperature corresponding to the Becker-Doring limit. The classical picture of a free energy barrier was reformulated to explain this cross-over behavior. Next, photon correlation spectroscopy was used to study the dependence of the transient nucleation behavior on the initial states. A unique feature of this study is that this initial state can be conveniently adjusted by varying the shear rate S to which the mixture is initially exposed. The shear is then turned off, and the number density N(t), as well as the mean radius of the growing droplets, is monitored as a function of time. It was possible to measure the droplet density at a very early stage of phase separation where the nucleation rate J was close to zero. The measurement reveals that N(t) depends critically on the initial state of the metastable system. When the shear is large enough to rupture the droplets as small as the critical size, N(t) increases very slowly. Measurements of the nucleation rates vs. the square of the

  8. Difference at chromospheric levels between rs cvn-type binaries, active and quiet chromosphere single stars, and active and quiet regions in the sun

    SciTech Connect

    Linsky, J.L.

    1980-01-01

    This paper summarizes the differences in the properties of active chromospheres compared with quiet chromospheres by comparing active and quiet regions on the Sun, active and quiet chromosphere stars, and the very active chromospheres seen in close binary systems with chromospheres of single stars. In particular, the chromospheres of the RS CVn-type binary systems UX Arietis and HR 1099 and the chromosphere of UX Arietis during a flare are modeled.

  9. Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

    NASA Astrophysics Data System (ADS)

    Porobova, Svetlana; Markova, Tat'jana; Klopotov, Vladimir; Klopotov, Anatoliy; Loskutov, Oleg; Vlasov, Viktor

    2016-01-01

    The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen's law.

  10. Planetary nebula progenitors that swallow binary systems

    NASA Astrophysics Data System (ADS)

    Soker, Noam

    2016-01-01

    I propose that some irregular messy planetary nebulae (PNe) owe their morphologies to triple-stellar evolution where tight binary systems evolve inside and/or on the outskirts of the envelope of asymptotic giant branch (AGB) stars. In some cases, the tight binary system can survive, in others, it is destroyed. The tight binary system might break up with one star leaving the system. In an alternative evolution, one of the stars of the broken-up tight binary system falls towards the AGB envelope with low specific angular momentum, and drowns in the envelope. In a different type of destruction process, the drag inside the AGB envelope causes the tight binary system to merge. This releases gravitational energy within the AGB envelope, leading to a very asymmetrical envelope ejection, with an irregular and messy PN as a descendant. The evolution of the triple-stellar system can be in a full common envelope evolution or in a grazing envelope evolution. Both before and after destruction (if destruction takes place), the system might launch pairs of opposite jets. One pronounced signature of triple-stellar evolution might be a large departure from axisymmetrical morphology of the descendant PN. I estimate that about one in eight non-spherical PNe is shaped by one of these triple-stellar evolutionary routes.

  11. Urey Prize Lecture: Binary Minor Planets

    NASA Astrophysics Data System (ADS)

    Margot, J. L.

    2004-11-01

    The discovery of binary systems in the near-Earth, main belt, and Kuiper belt populations provides an abundance of new data that expand our knowledge of the physics and chemistry of the solar system. Binary minor planets form as a result of collisional, tidal, and capture processes that are important to study as they play major roles in the formation and evolution of planetary systems. The frequency of occurrence of such processes directly reflects the dynamical environment in the various populations. Observations of binaries provide a powerful way to measure the bulk properties of small bodies, which in turn lead to inferences about their composition and internal structure. These data may offer a rare glimpse of what physical and chemical conditions prevailed when protoplanets formed, and what subsequent evolution took place. In the case of the Kuiper Belt, the study of a handful of binaries forces us to rethink how dense and how bright these bodies are, and to significantly revise our current mass estimates for the entire population. The number of known binary minor planets has increased dramatically over the past few years, with roughly ten new discoveries each year. I will attempt to summarize recent developments, with examples drawn from my observations with the Hubble, Palomar, Keck, Arecibo and Goldstone telescopes.

  12. Keck Imaging of Binary L Dwarfs.

    PubMed

    Koerner; Kirkpatrick; McElwain; Bonaventura

    1999-11-20

    We present Keck near-infrared imaging of three binary L dwarf systems, all of which are likely to be substellar. Two are lithium dwarfs, and a third exhibits an L7 spectral type, making it the coolest binary known to date. All have component flux ratios near 1 and projected physical separations between 5 and 10 AU, assuming distances of 18-26 pc from recent measurements of trigonometric parallax. These surprisingly similar binaries represent the sole detections of companions in 10 L dwarf systems that were analyzed in the preliminary phase of a much larger dual-epoch imaging survey. The detection rate prompts us to speculate that binary companions to L dwarfs are common, that similar-mass systems predominate, and that their distribution peaks at radial distances in accord both with M dwarf binaries and with the radial location of Jovian planets in our own solar system. To fully establish these conjectures against doubts raised by biases inherent in this small preliminary survey, however, will require quantitative analysis of a larger volume-limited sample that has been observed with high resolution and dynamic range. PMID:10534453

  13. Orbital eccentricities in primordial black hole binaries

    NASA Astrophysics Data System (ADS)

    Cholis, Ilias; Kovetz, Ely D.; Ali-Haïmoud, Yacine; Bird, Simeon; Kamionkowski, Marc; Muñoz, Julian B.; Raccanelli, Alvise

    2016-10-01

    It was recently suggested that the merger of ˜30 M⊙ primordial black holes (PBHs) may provide a significant number of events in gravitational-wave observatories over the next decade, if they make up an appreciable fraction of the dark matter. Here we show that measurement of the eccentricities of the inspiralling binary black holes can be used to distinguish these binaries from those produced by more traditional astrophysical mechanisms. These PBH binaries are formed on highly eccentric orbits and can then merge on time scales that in some cases are years or less, retaining some eccentricity in the last seconds before the merger. This is to be contrasted with massive-stellar-binary, globular-cluster, or other astrophysical origins for binary black holes (BBHs) in which the orbits have very effectively circularized by the time the BBH enters the observable LIGO window. Here we discuss the features of the gravitational-wave signals that indicate this eccentricity and forecast the sensitivity of LIGO and the Einstein Telescope to such effects. We show that if PBHs make up the dark matter, then roughly one event should have a detectable eccentricity given LIGO's expected sensitivity and observing time of six years. The Einstein Telescope should see O (10 ) such events after ten years.

  14. The binary white dwarf LHS 3236

    SciTech Connect

    Harris, Hugh C.; Dahn, Conard C.; Canzian, Blaise; Guetter, Harry H.; Levine, Stephen E.; Luginbuhl, Christian B.; Monet, Alice K. B.; Stone, Ronald C.; Subasavage, John P.; Tilleman, Trudy; Walker, Richard L.; Dupuy, Trent J.; Liu, Michael C.; Hartkopf, William I.; Ireland, Michael J.; Leggett, S. K.

    2013-12-10

    The white dwarf LHS 3236 (WD1639+153) is shown to be a double-degenerate binary, with each component having a high mass. Astrometry at the U.S. Naval Observatory gives a parallax and distance of 30.86 ± 0.25 pc and a tangential velocity of 98 km s{sup –1}, and reveals binary orbital motion. The orbital parameters are determined from astrometry of the photocenter over more than three orbits of the 4.0 yr period. High-resolution imaging at the Keck Observatory resolves the pair with a separation of 31 and 124 mas at two epochs. Optical and near-IR photometry give a set of possible binary components. Consistency of all data indicates that the binary is a pair of DA stars with temperatures near 8000 and 7400 K and with masses of 0.93 and 0.91 M {sub ☉}; also possible is a DA primary and a helium DC secondary with temperatures near 8800 and 6000 K and with masses of 0.98 and 0.69 M {sub ☉}. In either case, the cooling ages of the stars are ∼3 Gyr and the total ages are <4 Gyr. The combined mass of the binary (1.66-1.84 M {sub ☉}) is well above the Chandrasekhar limit; however, the timescale for coalescence is long.

  15. Eclipsing binaries in the MOST satellite fields

    NASA Astrophysics Data System (ADS)

    Pribulla, T.; Rucinski, S. M.; Latham, D. W.; Quinn, S. N.; Siwak, M.; Matthews, J. M.; Kuschnig, R.; Rowe, J. F.; Guenther, D. B.; Moffat, A. F. J.; Sasselov, D.; Walker, G. A. H.; Weiss, W. W.

    2010-04-01

    Sixteen new eclipsing binaries have been discovered by the MOST satellite among guide stars used to point its telescope in various fields. Several previously known eclipsing binaries were also observed by MOST with unprecedented quality. Among the objects we discuss in more detail are short-period eclipsing binaries with eccentric orbits in young open clusters: V578 Mon in NGC 2244 and HD 47934 in NGC 2264. Long nearly-continuous photometric runs made it possible to discover three long-period eclipsing binaries with orbits seen almost edge-on: HD 45972 with P = 28.1 days and two systems (GSC 154 1247 and GSC 2141 526) with P > 25 days. The high precision of the satellite data led to discoveries of binaries with very shallow eclipses (e.g., HD 46180 with A = 0.016 mag, and HD 47934 with A = 0.025 mag). Ground-based spectroscopy to support the space-based photometry was used to refine the models of several of the systems. Based on photometric data from MOST, a Canadian Space Agency mission (jointly operated by Microsat Systems Canada Inc. (formerly the Space Division of Dynacon Inc.), the University of Toronto Institute for Aerospace Studies - SpaceFlight Lab and the University of British Columbia, with the assistance of the University of Vienna), and on spectroscopic data from the David Dunlap Observatory, University of Toronto, and Las Campanas Observatory, Carnegie Institute Washington.

  16. Planet scattering around binaries: ejections, not collisions

    NASA Astrophysics Data System (ADS)

    Smullen, Rachel A.; Kratter, Kaitlin M.; Shannon, Andrew

    2016-09-01

    Transiting circumbinary planets discovered by Kepler provide unique insight into binary star and planet formation. Several features of this new found population, for example the apparent pile-up of planets near the innermost stable orbit, may distinguish between formation theories. In this work, we determine how planet-planet scattering shapes planetary systems around binaries as compared to single stars. In particular, we look for signatures that arise due to differences in dynamical evolution in binary systems. We carry out a parameter study of N-body scattering simulations for four distinct planet populations around both binary and single stars. While binarity has little influence on the final system multiplicity or orbital distribution, the presence of a binary dramatically affects the means by which planets are lost from the system. Most circumbinary planets are lost due to ejections rather than planet-planet or planet-star collisions. The most massive planet in the system tends to control the evolution. Systems similar to the only observed multiplanet circumbinary system, Kepler-47, can arise from much more tightly packed, unstable systems. Only extreme initial conditions introduce differences in the final planet populations. Thus, we suggest that any intrinsic differences in the populations are imprinted by formation.

  17. Forming the wide asynchronous binary asteroid population

    NASA Astrophysics Data System (ADS)

    Jacobson, S.; Scheeres, D.; McMahon, J.

    2014-07-01

    We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semi-major axes relative to most near-Earth-asteroid and main-belt-asteroid systems as shown in the attached table. Confirmed members have rapidly rotating primaries and satellites that are not tidally locked. Previously suggested formation mechanisms from impact ejecta, from planetary flybys, and directly from rotational-fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (1) these systems are formed from rotational fission, (2) their satellites are tidally locked, (3) their orbits are expanded by the binary Yarkovsky-O'Keefe-Radzievskii-Paddack (BYORP) effect, (4) their satellites desynchronize as a result of the adiabatic invariance between the libration of the secondary and the mutual orbit, and (5) the secondary avoids resynchronization because of the YORP effect. This seemingly complex chain of events is a natural pathway for binaries with satellites that have particular shapes, which define the BYORP effect torque that acts on the system. After detailing the theory, we analyze each of the wide-asynchronous-binary members and candidates to assess their most likely formation mechanism. Finally, we suggest possible future observations to check and constrain our hypothesis.

  18. Are neutron stars crushed? Gravitomagnetic tidal forces as a mechanism for binary-induced collapse

    NASA Astrophysics Data System (ADS)

    Favata, Marc; Thorne, Kip S.

    2002-04-01

    Numerical simulations of coalescing binary neutron stars performed by Wilson, Mathews, and Marronetti indicated that a binary companion could cause a stable neutron star to undergo gravitational collapse prior to merger if the neutron star is close to its maximum allowed mass. Subsequent studies by several authors failed to explain this surprising effect. Although Flanagan’s correction accounted for most of the effect, a small residual compression remained. This has prompted us to ask: what physical mechanism, if any, could cause binary-induced compression of a neutron star? We have found that a compressive force can exist when gravitomagnetic tidal fields, generated by the companion's orbital motion, couple to certain velocity patterns (or modes of stellar oscillation) in the neutron star. Specifically, we find that if one decomposes the star's fluid velocity into a sum over vector spherical harmonics, a radial compression force exists for certain vector harmonic indices. However, this force can only affect stability if the star is already very close to its maximum mass. We derive expressions for the evolution of the star's fundamental radial mode (along which compression and expansion occur) and the change in the central density. We also estimate how close a neutron star needs to be to its maximum mass in order for this compression to initiate gravitational collapse. Our analysis demonstrates techniques that can be applied to the study of relativistic tidal fields on various modes of stellar oscillation.

  19. WIND-SHEARING IN GASEOUS PROTOPLANETARY DISKS AND THE EVOLUTION OF BINARY PLANETESIMALS

    SciTech Connect

    Perets, Hagai B.; Murray-Clay, Ruth A.

    2011-05-20

    One of the first stages of planet formation is the growth of small planetesimals and their accumulation into large planetesimals and planetary embryos. This early stage occurs much before the dispersal of most of the gas from the protoplanetary disk. Due to their different aerodynamic properties, planetesimals of different sizes and shapes experience different drag forces from the gas during this time. Such differential forces produce a wind-shearing (WISH) effect between close by, different-sized planetesimals. For any two planetesimals, a WISH radius can be considered at which the differential acceleration due to the wind becomes greater than the mutual gravitational pull between the planetesimals. We find that the WISH radius could be much smaller than the gravitational shearing radius by the star (the Hill radius). In other words, during the gas-phase of the disk, WISH could play a more important role than tidal perturbations by the star. Here, we study the WISH radii for planetesimal pairs of different sizes and compare the effects of wind and gravitational shearing (drag force versus gravitational tidal force). We then discuss the role of WISH for the stability and survival of binary planetesimals. Binaries are sheared apart by the wind if they are wider than their WISH radius. WISH-stable binaries can also inspiral, and possibly coalesce, due to gas drag. Here, we calculate the WISH radius and the gas-drag-induced merger timescale, providing stability and survival criteria for gas-embedded binary planetesimals. Our results suggest that even WISH-stable binaries may merge in times shorter than the lifetime of the gaseous disk. This may constrain currently observed binary planetesimals to have formed far from the star or at a late stage after the dispersal of most of the disk gas. We note that the WISH radius may also be important for other processes such as planetesimal erosion and planetesimal encounters and collisions in a gaseous environment.

  20. Hydrodynamical simulations of the tidal stripping of binary stars by massive black holes

    NASA Astrophysics Data System (ADS)

    Mainetti, Deborah; Lupi, Alessandro; Campana, Sergio; Colpi, Monica

    2016-04-01

    In a galactic nucleus, a star on a low angular momentum orbit around the central massive black hole can be fully or partially disrupted by the black hole tidal field, lighting up the compact object via gas accretion. This phenomenon can repeat if the star, not fully disrupted, is on a closed orbit. Because of the multiplicity of stars in binary systems, also binary stars may experience in pairs such a fate, immediately after being tidally separated. The consumption of both the binary components by the black hole is expected to power a double-peaked flare. In this paper, we perform for the first time, with GADGET2, a suite of smoothed particle hydrodynamics simulations of binary stars around a galactic central black hole in the Newtonian regime. We show that accretion luminosity light curves from double tidal disruptions reveal a more prominent knee, rather than a double peak, when decreasing the impact parameter of the encounter and when elevating the difference between the mass of the star which leaves the system after binary separation and the mass of the companion. The detection of a knee can anticipate the onset of periodic accretion luminosity flares if one of the stars, only partially disrupted, remains bound to the black hole after binary separation. Thus knees could be precursors of periodic flares, which can then be predicted, followed up and better modelled. Analytical estimates in the black hole mass range 105-108 M⊙ show that the knee signature is enhanced in the case of black holes of mass 106-107 M⊙.

  1. Time-Dependent Behavior of the O'Connell Effect in Eclipsing Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Beaky, Matthew M.; Koju, V.

    2012-05-01

    The characteristic shape of an eclipsing binary light curve consists of two out-of-eclipse maxima and two mid-eclipse minima. Many eclipsing binary light curves exhibit unequally high maxima, a feature known as the O'Connell effect. So far, this asymmetry has not been convincingly explained aside from a few individual systems. Most theories attribute the O'Connell effect to phenomena such as starspots, clouds of circumstellar gas and dust, or a hot spot caused by the impact of a mass-transferring gas stream. The high precision and nearly continuous temporal coverage of light curves produced by the Kepler Space Mission make it possible to detect variations in the O'Connell effect within individual systems that have not previously been observed via ground-based observations. Our analysis of Kepler light curves of eclipsing binary systems reveals that in most cases the size and even the sign of the O'Connell effect changes significantly over time scales of weeks or months. Moreover, the magnitude difference between the eclipse minima also varies, usually lagging behind the variations in the difference between the out-of-eclipse maxima by several orbital cycles. We have created models of eclipsing binary systems using Binary Maker 3 that include starspots that migrate slowly in longitude, and have analyze the light curves generated by these model systems. Models with constant starspots at fixed latitude and models with starspots that vary in size and latitude both reproduce the qualitative behavior of the time-dependent O'Connell effect in the Kepler light curves very closely. These results provide support for the notion that the O'Connell effect, at least in some cases, is caused by migrating starspots on the surface of one or both components of the binary star system.

  2. KEPLER STUDIES OF LOW-MASS ECLIPSING BINARIES. I. PARAMETERS OF THE LONG-PERIOD BINARY KIC 6131659

    SciTech Connect

    Bass, Gideon; Orosz, Jerome A.; Welsh, William F.; Windmiller, Gur; Gregg, Trevor Ames; Fetherolf, Tara; Wade, Richard A.; Quinn, Samuel N.

    2012-12-20

    KIC 6131659 is a long-period (17.5 days) eclipsing binary discovered by the Kepler mission. We analyzed six quarters of Kepler data along with supporting ground-based photometric and spectroscopic data to obtain accurate values for the mass and radius of both stars, namely, M{sub 1} = 0.922 {+-} 0.007 M{sub Sun }, R{sub 1} = 0.8800 {+-} 0.0028 R{sub Sun }, and M{sub 2} = 0.685 {+-} 0.005 M{sub Sun }, R{sub 2} = 0.6395 {+-} 0.0061 R{sub Sun }. There is a well-known issue with low-mass (M {approx}< 0.8 M{sub Sun }) stars (in cases where the mass and radius measurement uncertainties are smaller than 2% or 3%) where the measured radii are almost always 5% to 15% larger than expected from evolutionary models, i.e., the measured radii are all above the model isochrones in a mass-radius plane. In contrast, the two stars in KIC 6131659 were found to sit on the same theoretical isochrone in the mass-radius plane. Until recently, all of the well-studied eclipsing binaries with low-mass stars had periods of less than about three days. The stars in such systems may have been inflated by high levels of stellar activity induced by tidal effects in these close binaries. KIC 6131659 shows essentially no evidence of enhanced stellar activity, and our measurements support the hypothesis that the unusual mass-radius relationship observed in most low-mass stars is influenced by strong magnetic activity created by the rapid rotation of the stars in tidally locked, short-period systems. Finally, using short cadence data, we show that KIC 6131657 has one of the smallest measured non-zero eccentricities of a binary with two main-sequence stars, where ecos {omega} (4.57 {+-} 0.02) Multiplication-Sign 10{sup -5}.

  3. Photometric parameters, distance and period-colour study of contact binary stars in the globular cluster ω Centauri

    NASA Astrophysics Data System (ADS)

    Kiron, Y. Ravi; Sriram, K.; Vivekananda Rao, P.

    2011-06-01

    We present V passband photometric solutions of six contact binaries in the globular cluster ω Centauri using the Wilson-Devinney code. We found that four of the systems are H subtype W UMa binary systems and remaining two are W-subtype W UMa systems. Four of the systems show the O'Connell effect in their light curves and brightness at 0.75 phase is about δV=0.04-0.05 less than at 0.25 phase. We show that one dark/cool spot solution on secondary companion satisfactorily fits the observed light curves for the respective contact binaries. The derived spot values are not unique and they are taken to be tentative at best. The colour index of the six contact binaries were used to derive the distance modulus of ω Centauri and found an average value of ˜13.60 which is close to the observed value of 13.97. We also derive the distance to each of the studied variables. The period-colour relation of the contact binaries of ω Centauri is compared with the period-colour relation of Hipparcos data (field W UMa type) and contact binaries present in other globular clusters.

  4. Photometric and Period Investigation of the Late F-type Overcontact Binary II UMa

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Qian, S.-B.; Zhang, J.; Zhang, B.; Kreiner, J.

    2016-03-01

    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 (B V RcIc) 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=1.99{M}⊙ and {M}2=0.34{M}⊙ . 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=1.34{M}⊙ . 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× {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.

  5. Properties of the components in young binary systems

    NASA Astrophysics Data System (ADS)

    Woitas, Jens

    1999-10-01

    Using near-infrared speckle-interferometry we have obtained resolved JHK-photometry for the components of 58 young binary systems. By placing the components into a color-color diagram we identify some unusual red objects that are candidates for infrared companions or substellar objects. We place a subsample that consists of the components of 14 weak-lined TTS systems (where no significant circumstellar excess emission is expected) into a color-magnitude diagram and show that in all these systems the components are coeval within the uncertainties. Particularly this is the case for the triple system HBC 358. Using the J-magnitude as an indicator for the stellar luminosity, the optical spectral type of the system and the previously justified assumption that all components are coeval we can place the components into the HRD and derive their masses by comparison with theoretical pre-main sequence evolutionary tracks. The results are the following: The distribution of mass ratios is neither clustered towards M2 / M1 = 1 nor is it a function of the primary's mass or the components' projected separation. Comparison of these results with predictions of theoretical multiple star formation models suggests that most of the systems have formed by fragmentation during protostellar collapse, and that the components' masses are principally determined by fragmentation and not by the following accretion processes. Furthermore the infrared source HV Tau C is discussed using new observational data. We show that this source is no Herbig-Haro object, but an active T Tauri star. So the HV Tau-system does not impose a problem on current models of T Tauri stars and their environment. From relative positions of the components at different epochs we derive their relative velocities and show that in most close systems orbital motion can be proved. The analysis of this orbital motion leads to an empirical mass estimate for T Tauri-stars which is larger than the masses one would expect from the

  6. Hybrid black-hole binary initial data

    NASA Astrophysics Data System (ADS)

    Mundim, Bruno; Kelly, Bernard; Zlochower, Yosef; Nakano, Hiroyuki; Campanelli, Manuela

    2011-04-01

    Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al. [Class.Quant.Grav.27:114005,2010], a new binary black-hole initial data with radiation contents derived in the post-Newtonian (PN) calculation was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless ``wavy'' metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesired features; the unphysical horizon mass loss and the large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features. Thanks NSF and NASA for support.

  7. Compact binary hashing for music retrieval

    NASA Astrophysics Data System (ADS)

    Seo, Jin S.

    2014-03-01

    With the huge volume of music clips available for protection, browsing, and indexing, there is an increased attention to retrieve the information contents of the music archives. Music-similarity computation is an essential building block for browsing, retrieval, and indexing of digital music archives. In practice, as the number of songs available for searching and indexing is increased, so the storage cost in retrieval systems is becoming a serious problem. This paper deals with the storage problem by extending the supervector concept with the binary hashing. We utilize the similarity-preserving binary embedding in generating a hash code from the supervector of each music clip. Especially we compare the performance of the various binary hashing methods for music retrieval tasks on the widely-used genre dataset and the in-house singer dataset. Through the evaluation, we find an effective way of generating hash codes for music similarity estimation which improves the retrieval performance.

  8. Jets in black-hole binaries

    NASA Astrophysics Data System (ADS)

    Zdziarski, Andrzej

    2016-07-01

    I will review selected aspects of observations and theory of jets in black-hole binaries. The radio and gamma-ray emission of jets differs significantly between the low and high-mass X-ray binaries, which appears to be due jet-wind interaction (in particular, formation of recollimation shocks) in the latter. Also, both radio and X-ray emission of the jets can be significantly absorbed in the stellar wind of the donors in high-mass binaries. I will also review the theory of radiative processes in jets, their contributions to broad-band spectra, estimates of the jet power, the role of black-hole spin in powering jets, and the possibility that the base of the jet is the main source of X-ray emission (the lamppost model).

  9. Hybrid Black-Hole Binary Initial Data

    NASA Technical Reports Server (NTRS)

    Mundim, Bruno C.; Kelly, Bernard J.; Nakano, Hiroyuki; Zlochower, Yosef; Campanelli, Manuela

    2010-01-01

    "Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al. [Class. Quantum Grav. 27:114005 (2010)], a new binary black-hole initial data with radiation contents derived in the post-Newtonian (PN) calculations was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless "wavy" metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesired features; the unphysical horizon mass loss and the large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features."

  10. Binary Asteroids and Human Exploration Considerations

    NASA Technical Reports Server (NTRS)

    Abell, P. A.

    2013-01-01

    In 2009 the Augustine Commission identified near-Earth asteroids (NEAs) as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. Subsequently, the U.S. presidential administration directed NASA on April 15, 2010 to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010. Current NASA plans to explore NEAs do not include binary systems. However, with a few in situ robotic precursor missions to binary NEAs, and increased confidence in human mission capabilities, the scientific and hazard mitigation benefits, along with the programmatic and operational benefits of a human venture beyond the Earth-Moon system, make a mission to a binary NEA using NASA's proposed exploration systems a compelling endeavor.

  11. Rapid Compact Binary Coalescence Parameter Estimation

    NASA Astrophysics Data System (ADS)

    Pankow, Chris; Brady, Patrick; O'Shaughnessy, Richard; Ochsner, Evan; Qi, Hong

    2016-03-01

    The first observation run with second generation gravitational-wave observatories will conclude at the beginning of 2016. Given their unprecedented and growing sensitivity, the benefit of prompt and accurate estimation of the orientation and physical parameters of binary coalescences is obvious in its coupling to electromagnetic astrophysics and observations. Popular Bayesian schemes to measure properties of compact object binaries use Markovian sampling to compute the posterior. While very successful, in some cases, convergence is delayed until well after the electromagnetic fluence has subsided thus diminishing the potential science return. With this in mind, we have developed a scheme which is also Bayesian and simply parallelizable across all available computing resources, drastically decreasing convergence time to a few tens of minutes. In this talk, I will emphasize the complementary use of results from low latency gravitational-wave searches to improve computational efficiency and demonstrate the capabilities of our parameter estimation framework with a simulated set of binary compact object coalescences.

  12. The Outflows of Binary AGB Stars

    NASA Astrophysics Data System (ADS)

    Ramstedt, S.; Vlemmings, W. H. T.; Mohamed, S.

    2015-12-01

    The required conditions for stars to evolve into planetary nebulae (PNs) continues to puzzle. Since PNs are found in a wide variety of shapes, processes that could sculpt circumstellar envelopes (CSEs) are being investigated. A binary companion will have a strong gravitational effect, but known binary AGB stars are rare. Using ALMA in Cycle 1 and 2, we have observed a small sample of well-studied, binary AGB stars, covering a decisive range in separation, in order to determine the influence of a companion on the circumstellar morphology of the AGB primary. The first steps toward interpreting and analyzing the data have been taken, and the results will be compared to 3D Smoothed Particle Hydrodynamics (SPH) models of the gravitational interaction.

  13. Gravitational Wave Physics with Binary Love Relations

    NASA Astrophysics Data System (ADS)

    Yagi, Kent; Yunes, Nicolas

    2016-03-01

    Gravitational waves from the late inspiral of neutron star binaries encode rich information about their internal structure at supranuclear densities through their tidal deformabilities. However, extracting the individual tidal deformabilities of the components of a binary is challenging with future ground-based gravitational wave interferometers due to degeneracies between them. We overcome this difficulty by finding new, approximate universal relations between the individual tidal deformabilities that depend on the mass ratio of the two stars and are insensitive to their internal structure. Such relations have applications not only to gravitational wave astrophysics, but also to nuclear physics as they improve the measurement accuracy of tidal parameters. Moreover, the relations improve our ability to test extreme gravity and perform cosmology with gravitational waves emitted from neutron star binaries.

  14. Semiparametric binary model for clustered survival data

    NASA Astrophysics Data System (ADS)

    Arlin, Rifina; Ibrahim, Noor Akma; Arasan, Jayanthi; Bakar, Rizam Abu

    2015-10-01

    This paper considers a method to analyze semiparametric binary models for clustered survival data when the responses are correlated. We extend parametric generalized estimating equation (GEE) to semiparametric GEE by introducing smoothing spline into the model. A backfitting algorithm is used in the derivation of the estimating equation for the parametric and nonparametric components of a semiparametric binary covariate model. The properties of the estimates for both are evaluated using simulation studies. We investigated the effects of the strength of cluster correlation and censoring rates on properties of the parameters estimate. The effect of the number of clusters and cluster size are also discussed. Results show that the GEE-SS are consistent and efficient for parametric component and nonparametric component of semiparametric binary covariates.

  15. TIDAL NOVAE IN COMPACT BINARY WHITE DWARFS

    SciTech Connect

    Fuller, Jim; Lai Dong

    2012-09-01

    Compact binary white dwarfs (WDs) undergoing orbital decay due to gravitational radiation can experience significant tidal heating prior to merger. In these WDs, the dominant tidal effect involves the excitation of outgoing gravity waves in the inner stellar envelope and the dissipation of these waves in the outer envelope. As the binary orbit decays, the WDs are synchronized from outside in (with the envelope synchronized first, followed by the core). We examine the deposition of tidal heat in the envelope of a carbon-oxygen WD and study how such tidal heating affects the structure and evolution of the WD. We show that significant tidal heating can occur in the star's degenerate hydrogen layer. This layer heats up faster than it cools, triggering runaway nuclear fusion. Such 'tidal novae' may occur in all WD binaries containing a CO WD, at orbital periods between 5 minutes and 20 minutes, and precede the final merger by 10{sup 5}-10{sup 6} years.

  16. Long-term eclipse timing of white dwarf binaries: an observational hint of a magnetic mechanism at work

    NASA Astrophysics Data System (ADS)

    Bours, M. C. P.; Marsh, T. R.; Parsons, S. G.; Dhillon, V. S.; Ashley, R. P.; Bento, J. P.; Breedt, E.; Butterley, T.; Caceres, C.; Chote, P.; Copperwheat, C. M.; Hardy, L. K.; Hermes, J. J.; Irawati, P.; Kerry, P.; Kilkenny, D.; Littlefair, S. P.; McAllister, M. J.; Rattanasoon, S.; Sahman, D. I.; Vučković, M.; Wilson, R. W.

    2016-08-01

    We present a long-term programme for timing the eclipses of white dwarfs in close binaries to measure apparent and/or real variations in their orbital periods. Our programme includes 67 close binaries, both detached and semi-detached and with M-dwarfs, K-dwarfs, brown dwarfs or white dwarfs secondaries. In total, we have observed more than 650 white dwarf eclipses. We use this sample to search for orbital period variations and aim to identify the underlying cause of these variations. We find that the probability of observing orbital period variations increases significantly with the observational baseline. In particular, all binaries with baselines exceeding 10 yr, with secondaries of spectral type K2 - M5.5, show variations in the eclipse arrival times that in most cases amount to several minutes. In addition, among those with baselines shorter than 10 yr, binaries with late spectral type (>M6), brown dwarf or white dwarf secondaries appear to show no orbital period variations. This is in agreement with the so-called Applegate mechanism, which proposes that magnetic cycles in the secondary stars can drive variability in the binary orbits. We also present new eclipse times of NN Ser, which are still compatible with the previously published circumbinary planetary system model, although only with the addition of a quadratic term to the ephemeris. Finally, we conclude that we are limited by the relatively short observational baseline for many of the binaries in the eclipse timing programme, and therefore cannot yet draw robust conclusions about the cause of orbital period variations in evolved, white dwarf binaries.

  17. The closed fuel cycle

    SciTech Connect

    Froment, Antoine; Gillet, Philippe

    2007-07-01

    Available in abstract form only. Full text of publication follows: The fast growth of the world's economy coupled with the need for optimizing use of natural resources, for energy security and for climate change mitigation make energy supply one of the 21. century most daring challenges. The high reliability and efficiency of nuclear energy, its competitiveness in an energy market undergoing a new oil shock are as many factors in favor of the 'renaissance' of this greenhouse gas free energy. Over 160,000 tHM of LWR1 and AGR2 Used Nuclear Fuel (UNF) have already been unloaded from the reactor cores corresponding to 7,000 tons discharged per year worldwide. By 2030, this amount could exceed 400,000 tHM and annual unloading 14,000 tHM/year. AREVA believes that closing the nuclear fuel cycle through the treatment and recycling of Used Nuclear Fuel sustains the worldwide nuclear power expansion. It is an economically sound and environmentally responsible choice, based on the preservation of natural resources through the recycling of used fuel. It furthermore provides a safe and secure management of wastes while significantly minimizing the burden left to future generations. (authors)

  18. Reconciliation with non-binary species trees.

    PubMed

    Vernot, Benjamin; Stolzer, Maureen; Goldman, Aiton; Durand, Dannie

    2008-10-01

    Reconciliation extracts information from the topological incongruence between gene and species trees to infer duplications and losses in the history of a gene family. The inferred duplication-loss histories provide valuable information for a broad range of biological applications, including ortholog identification, estimating gene duplication times, and rooting and correcting gene trees. While reconciliation for binary trees is a tractable and well studied problem, there are no algorithms for reconciliation with non-binary species trees. Yet a striking proportion of species trees are non-binary. For example, 64% of branch points in the NCBI taxonomy have three or more children. When applied to non-binary species trees, current algorithms overestimate the number of duplications because they cannot distinguish between duplication and incomplete lineage sorting. We present the first algorithms for reconciling binary gene trees with non-binary species trees under a duplication-loss parsimony model. Our algorithms utilize an efficient mapping from gene to species trees to infer the minimum number of duplications in O(|V(G) | x (k(S) + h(S))) time, where |V(G)| is the number of nodes in the gene tree, h(S) is the height of the species tree and k(S) is the size of its largest polytomy. We present a dynamic programming algorithm which also minimizes the total number of losses. Although this algorithm is exponential in the size of the largest polytomy, it performs well in practice for polytomies with outdegree of 12 or less. We also present a heuristic which estimates the minimal number of losses in polynomial time. In empirical tests, this algorithm finds an optimal loss history 99% of the time. Our algorithms have been implemented in NOTUNG, a robust, production quality, tree-fitting program, which provides a graphical user interface for exploratory analysis and also supports automated, high-throughput analysis of large data sets.

  19. OSRI: a rotationally invariant binary descriptor.

    PubMed

    Xu, Xianwei; Tian, Lu; Feng, Jianjiang; Zhou, Jie

    2014-07-01

    Binary descriptors are becoming widely used in computer vision field because of their high matching efficiency and low memory requirements. Since conventional approaches, which first compute a floating-point descriptor then binarize it, are computationally expensive, some recent efforts have focused on directly computing binary descriptors from local image patches. Although these binary descriptors enable a significant speedup in processing time, their performances usually drop a lot due to orientation estimation errors and limited description abilities. To address these issues, we propose a novel binary descriptor based on the ordinal and spatial information of regional invariants (OSRIs) over a rotation invariant sampling pattern. Our main contributions are twofold: 1) each bit in OSRI is computed based on difference tests of regional invariants over pairwise sampling-regions instead of difference tests of pixel intensities commonly used in existing binary descriptors, which can significantly enhance the discriminative ability and 2) rotation and illumination changes are handled well by ordering pixels according to their intensities and gradient orientations, meanwhile, which is also more reliable than those methods that resort to a reference orientation for rotation invariance. Besides, a statistical analysis of discriminative abilities of different parts in the descriptor is conducted to design a cascade filter which can reject nonmatching descriptors at early stages by comparing just a small portion of the whole descriptor, further reducing the matching time. Extensive experiments on four challenging data sets (Oxford, 53 Objects, ZuBuD, and Kentucky) show that OSRI significantly outperforms two state-of-the-art binary descriptors (FREAK and ORB). The matching performance of OSRI with only 512 bits is also better than the well-known floating-point descriptor SIFT (4K bits) and is comparable with the state-of-the-art floating-point descriptor MROGH (6K bits

  20. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. I. S-TYPE BINARIES

    SciTech Connect

    Kaltenegger, Lisa; Haghighipour, Nader

    2013-11-10

    We have developed a comprehensive methodology for calculating the boundaries of the habitable zone (HZ) of planet-hosting S-type binary star systems. Our approach is general and takes into account the contribution of both stars to the location and extent of the binary HZ with different stellar spectral types. We have studied how the binary eccentricity and stellar energy distribution affect the extent of the HZ. Results indicate that in binaries where the combination of mass-ratio and orbital eccentricity allows planet formation around a star of the system to proceed successfully, the effect of a less luminous secondary on the location of the primary's HZ is generally negligible. However, when the secondary is more luminous, it can influence the extent of the HZ. We present the details of the derivations of our methodology and discuss its application to the binary HZ around the primary and secondary main-sequence stars of an FF, MM, and FM binary, as well as two known planet-hosting binaries α Cen AB and HD 196886.