scholarly journals Tidal Modulation of Radial Oscillations in Components of Circular-Orbit Close Binaries

2002 ◽  
Vol 185 ◽  
pp. 80-81
Author(s):  
T. Reyniers ◽  
P. Smeyers
Keyword(s):  
Circular Orbit ◽  
Orbital Motion ◽  
Theoretical Description ◽  
Radial Oscillation ◽  
Close Binary ◽  
Close Binaries ◽  
Rotating Star

AbstractA theoretical description is presented of the modulation of a radial oscillation in a uniformly rotating star in a close binary that is subject to the tidal action of a companion moving in a circular orbit. The star is assumed to rotate non-synchronously with the companion’s orbital motion. A tidal modulation of a radial oscillation has been observed in the star θ Tucanae by Sterken (1997) and De Mey et al. (1998).

scholarly journals Pulsars and Close Binary Systems

1971 ◽  
Vol 46 ◽  
pp. 273-278
Author(s):  
Virginia Trimble ◽  
Martin Rees
Keyword(s):  
Mass Transfer ◽  
Neutron Stars ◽  
Binary Systems ◽  
Alternative Explanation ◽  
Galactic Plane ◽  
Orbital Motion ◽  
Close Binary ◽  
Close Binaries ◽  
Close Binary Systems ◽  
Supernova Explosions

It is first considered what must happen if pulsars (i.e. neutron stars) are formed in close binary systems (CBS), and whether the resulting orbital motion and mass transfer should be observable. As this set of alternatives seems unlikely, there follow suggestions of how one might prevent the formation of neutron stars in close binaries. Finally, it is shown that ‘runaway’ pulsars with velocities larger than about 15 km/sec cannot be produced by isotropic supernova explosions within close binaries, and an alternative explanation is suggested for the observed correlation of periods of pulsars with their distances from the galactic plane.

scholarly journals Probing the elliptical orbital configuration of the close binary of supermassive black holes with differential interferometry

2020 ◽  
Vol 644 ◽  
pp. A88
Author(s):  
Andjelka B. Kovačević ◽  
Yu-Yang Songsheng ◽  
Jian-Min Wang ◽  
Luka Č. Popović
Keyword(s):  
Black Holes ◽  
Near Infrared ◽  
Orbital Motion ◽  
Supermassive Black Holes ◽  
Spectral Lines ◽  
Close Binary ◽  
Close Binaries ◽  
Large Telescope ◽  
Differential Phase ◽  
Differential Interferometry

Context. Obtaining detections of electromagnetic signatures from the close binaries of supermassive black holes (CB-SMBH) is still a great observational challenge. The Very Large Telescope Interferometer (VLTI) and the Extremely Large Telescope (ELT) will serve as a robust astrophysics suite offering the opportunity to probe the structure and dynamics of CB-SMBH at a high spectral and angular resolution. Aims. Here, we explore and illustrate the application of differential interferometry on unresolved CB-SMBH systems in elliptical orbital configurations. We also investigate certain peculiarities of interferometry signals for a single SMBH with clouds in elliptical orbital motion. Methods. Photocentre displacements between each SMBH and the regions in their disc-like broad line regions (BLR) appear as small interferometric differential phase variability. To investigate the application of interferometric phases for the detection of CB-SMBH systems, we simulated a series of differential interferometry signatures, based on our model comprising ensembles of clouds surrounding each supermassive black hole in a CB-SMBH. By setting the model to the parameters of a single SMBH with elliptical cloud motion, we also calculated a series of differential interferometry observables for this case. Results. We found various deviations from the canonical S-shape of the CB-SMBH phase profile for elliptically configured CB-SMBH systems. The amplitude and specific shape of the interferometry observables depend on the orbital configurations of the CB-SMBH system. We get distinctive results when considering anti-aligned angular momenta of cloud orbits with regard to the total CB-SMBH angular momentum. We also show that their velocity distributions differ from the aligned cloud orbital motion. Some simulated spectral lines from our model closely resemble observations from the Paα line obtained from near-infrared AGN surveys. We found differences between the “zoo” of differential phases of single SMBH and CB-SMBH systems. The “zoo” of differential phases for a single SMBH take a deformed S shape. We also show how their differential phase shape, amplitude, and slope evolve with various sets of cloud orbital parameters and the observer’s position. Conclusions. We calculate an extensive atlas of the interferometric observables, revealing distinctive signatures for the elliptical configuration CB-SMBH. We also provide an interferometry atlas for the case of a single SMBH with clouds with an elliptical motion, which differs from those of a CB-SMBH. These maps can be useful for extracting exceptional features of the BLR structure from future high-resolution observations of CB-SMBH systems, but also of a single SMBH with clouds in an elliptical orbital setup.

scholarly journals Inverse tides in pulsating binary stars

2020 ◽  
Vol 501 (1) ◽  
pp. 483-490
Author(s):  
Jim Fuller
Keyword(s):  
Binary Stars ◽  
Close Binary ◽  
Close Binaries ◽  
Spin Orbit ◽  
Misalignment Angle ◽  
Stellar Rotation ◽  
Transfer Energy ◽  
Pulsating Stars ◽  
Mode Amplitude ◽  
Rotation Periods

ABSTRACT In close binary stars, the tidal excitation of pulsations typically dissipates energy, causing the system to evolve towards a circular orbit with aligned and synchronized stellar spins. However, for stars with self-excited pulsations, we demonstrate that tidal interaction with unstable pulsation modes can transfer energy in the opposite direction, forcing the spins of the stars away from synchronicity, and potentially pumping the eccentricity and spin–orbit misalignment angle. This ‘inverse’ tidal process only occurs when the tidally forced mode amplitude is comparable to the mode’s saturation amplitude, and it is thus most likely to occur in main-sequence gravity mode pulsators with orbital periods of a few days. We examine the long-term evolution of inverse tidal action, finding the stellar rotation rate can potentially be driven to a very large or very small value, while maintaining a large spin–orbit misalignment angle. Several recent asteroseismic analyses of pulsating stars in close binaries have revealed extremely slow core rotation periods, which we attribute to the action of inverse tides.

On Cluster Rotation in the Galactic Tidal Field

2014 ◽  
Vol 23 (3-4) ◽  
Author(s):  
Leonid P. Ossipkov
Keyword(s):  
Circular Orbit ◽  
Virial Theorem ◽  
Galactic Plane ◽  
Rotation Speed ◽  
Star Cluster ◽  
Rotating Star

AbstractThe dynamics of a rotating star cluster moving along a circular orbit in the axisymmetrical steady Galaxy is considered. The generalized tensor virial theorem allows to estimate its rotation speed. Conditions for direct and retrograde rotation in the galactic plane are found.

scholarly journals Empirical Determination of the Gravity-Darkening Exponent for the Secondary Components Filling the Roche Lobe in Semi-Detached Close Binary Systems

1988 ◽  
Vol 108 ◽  
pp. 217-218
Author(s):  
Masatoshi Kitamura ◽  
Yasuhisa Nakamura
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary System ◽  
Roche Lobe ◽  
Close Binary ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Local Gravity ◽  
Subsurface Layers

The ordinary semi-detached close binary system consists of a main-sequence primary and subgiant (or giant) secondary component where the latter fills the Roche lobe. From a quantitative analysis of the observed ellipticity effect, Kitamura and Nakamura (1986) have deduced empirical values of the exponent of gravity-darkening for distorted main-sequence stars in detached systems and found that the empirical values of the exponent for these stars with early-type spectra are close to the unity, indicating that the subsurface layers of early-main sequence stars in close binaries are actually in radiative equilibrium. The exponent of gravity-darkening can be defined by H ∝ gα with H as the bolonetric surface brightness and g as the local gravity on the stellar surface.

scholarly journals Close-In Substellar Companions and the Formation of sdB-Type Close Binary Stars

2015 ◽  
Vol 2 (1) ◽  
pp. 183-187 ◽  
Author(s):  
L. Y. Zhu ◽  
S. B. Qian ◽  
E.-G. Zhao ◽  
E. Fernández Lajús ◽  
Z.-T. Han
Keyword(s):  
Binary Stars ◽  
Eclipsing Binaries ◽  
Close Binary ◽  
Close Binaries ◽  
Close Binary Stars ◽  
Cataclysmic Binaries ◽  
Low Mass ◽  
Substellar Companions ◽  
Orbital Periods

The sdB-type close binaries are believed to have experienced a common-envelope phase and may evolve into cataclysmic binaries (CVs). About 10% of all known sdB binaries are eclipsing binaries consisting of very hot subdwarf primaries and low-mass companions with short orbital periods. The eclipse profiles of these systems are very narrow and deep, which benefits the determination of high precise eclipsing times and makes the detection of small and close-in tertiary bodies possible. Since 2006 we have monitored some sdB-type eclipsing binaries to search for the close-in substellar companions by analyzing the light travel time effect. Here some progresses of the program are reviewed and the formation of sdB-type binary is discussed.

scholarly journals Stream Parameters in the Neighbourhood of the L1 Point in W Serpentis-type Binaries

1995 ◽  
Vol 151 ◽  
pp. 112-114
Author(s):  
V.G. Karetnikov ◽  
E.V. Luthardt-Menchenkova ◽  
V.V. Nazarenko
Keyword(s):  
Binary Systems ◽  
Great Influence ◽  
Close Binary System ◽  
Small Extent ◽  
Close Binary ◽  
Close Binaries ◽  
Circumstellar Envelope ◽  
Hydrodynamic Method ◽  
Common Deficiency

The gas motion in close binary systems has been investigated by several authors using a hydrodynamic method (e.g. Prendergast & Taam 1974, Flannery 1975, Lubow & Shu 1975, 1976). All these researches have, besides important results, a common deficiency: in the analysis of the gas motion, the extent and velocity of the stream in the neighbourhood of the inner Lagrangian point L1 was not calculated. They have been chosen on the basis of general assumptions (the same for all types of close binaries). A fundamental assumption was the small extent of the stream in the neighbourhood of L1 perpendicular to the line connecting the centers of the stars. At the same time the extent and the velocity of the stream near L1 exert a great influence on the further stream motion, on the formation of the circumstellar envelope and finally on the evolution of the close binary system. Therefore the first step in the investigation of the gas motion in a close binary must be the determination of the initial parameters of the stream in the neighbourhood of the point L1.

42. Close Binary Stars (Etoiles Binaires Serrees)

1988 ◽  
Vol 20 (01) ◽  
pp. 569-594
Author(s):  
J. Smak ◽  
R.H. Koch ◽  
K.D. Abhyankar ◽  
J. Andersen ◽  
A.H. Batten ◽  
...  
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Spectroscopic Binaries ◽  
Close Binary ◽  
Close Binaries ◽  
Stellar Winds ◽  
Space Instruments ◽  
Close Binary Stars ◽  
Nuclear Burning ◽  
Astronomy And Astrophysics

During the XlXth General Assembly of the IAU in Delhi the number of members of Cotrmission 42 increased to 260. This simply reflects the growing interest and importance of our field. Growing is not only the number of astronomers involved in research on CBS but also the number of papers resulting from that activity. As an example one can quote the numbers of papers listed during the last few years in Sections 117 (Close Binaries), 119 (Eelipsing Binaries), and 120 (Spectroscopic Binaries) of theAstronomy and Astrophysics Abstracts:705(1982), 775(1983), 836(1984), 1080(1985), and 911(1986); note that many additional references could be added to these numbers from other sections. Naturally, such numbers alone do not reflect the quality and even less so the position and significance of the CBS field. Here one could perhaps mention an impressive record of successful research proposals involving requests for the observing time on large, ground based telescopes and on space instruments. Indeed, in spite of a very strong competition from other fields, programs involving CBS are usually placed very high on the priority lists (cf. Sections 2D and 2E). Obviously, the close binary systems, their evolution, and the physical processes which occur in them (accretion, stellar winds, nuclear burning, etc) appear interesting and important not only to those who are involved in their studies but also to astronomers from other fields.

scholarly journals Analytic properties of the electromagnetic field of binary compact stars and electromagnetic precursors to gravitational waves

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Tomoki Wada ◽  
Masaru Shibata ◽  
Kunihito Ioka
Keyword(s):  
Electromagnetic Field ◽  
Neutron Star ◽  
Gravitational Waves ◽  
Orbital Motion ◽  
Compact Stars ◽  
Close Binary ◽  
Radio Bursts ◽  
Poynting Flux ◽  
Electromagnetic Precursors ◽  
Spiral Arm

Abstract We analytically study the properties of the electromagnetic field in the vacuum around close binary compact stars containing at least one neutron star. We show that the orbital motion of the neutron star induces high multipole modes of the electromagnetic field just before the merger. These modes are superimposed to form a spiral arm configuration, and its edge is found to be a likely site for magnetic reconnection. These modes also enhance the total Poynting flux from neutron star binaries by a factor of 2–4. We also indicate that the electric field induced by the orbital motion leads to a magnetosphere around binaries and estimate its plasma density, which has a different parameter dependence than the Goldreich–Julian density. With these properties, we discuss possible electromagnetic counterparts to gravitational wave events, and identify radio precursors, such as fast radio bursts, as the most promising observational targets.

scholarly journals Irradiation Effects in Compact Binaries

2002 ◽  
Vol 187 ◽  
pp. 253-258
Author(s):  
Martin E. Beer ◽  
Philipp Podsiadlowski
Keyword(s):  
Binary Systems ◽  
Three Dimensional ◽  
Close Binary ◽  
Close Binaries ◽  
External Irradiation ◽  
Black Hole Binaries ◽  
Compact Binaries ◽  
Critical Configurations ◽  
Main Effects

AbstractIrradiation of the secondaries in close binary systems affects their appearance and can drastically change their internal structure and hence long-term evolution. In this paper we review the main effects of external irradiation in close binaries with compact primaries, such as the distortion of the shape of the secondary and the conditions for the occurrence of outer critical configurations, and apply these to normal X-ray binaries, including systems such as HZ Her/Her X-l, Vela X-l and black-hole binaries during outburst (e.g. Nova Sco). Particular emphasis will be given to the role of circulation driven by the external heating and the radiative surface stress. We have developed a three-dimensional fluid dynamics code for modelling these effects. We present initial results of self-consistent calculations for the circulation in irradiated systems and show how the inclusion of these effects is vital to the understanding and interpretation of any system where external irradiation of the secondary is significant.

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