scholarly journals Criteria of Dynamical Isolation of Binaries and Multiples

1996 ◽  
Vol 169 ◽  
pp. 531-532
Author(s):  
Ludmila Kiseleva ◽  
Joanna Anosova
Keyword(s):  
Strong Influence ◽  
Dynamical Behavior ◽  
Close Binary ◽  
Dynamical Processes ◽  
Objective Criterion ◽  
Triple Systems ◽  
Mass Ratios ◽  
Hierarchical Stability ◽  
New Criterion

In order to obtain an objective criterion for dynamical isolation of binaries within systems of large multiplicity we study numerically the dynamical behavior and average parameters of stable hierarchical triple systems containing a close binary. Using the new criterion for hierarchical stability of triple systems with different mass ratios of components (Kiseleva, Eggleton, Anosova 1994; Kiseleva, Eggleton, Orlov 1994) the perturbing force from the outer body on the close inner binary is estimated. On this basis, the critical separations are obtained when both inner and outer orbits are practically not perturbed. Because the dispersion of masses has a very strong influence on dynamical processes in N-body systems, mass ratios of subsystems, and sometimes within subsystems, should always be taken into account.

scholarly journals The Binaries from Unstable Triples. Dynamical Processes of Formation

1989 ◽  
Vol 8 ◽  
pp. 143-144
Author(s):  
Joanna P. Anosova
Keyword(s):  
Computer Simulations ◽  
Dynamical Evolution ◽  
Close Binary ◽  
Close Binaries ◽  
State University ◽  
Dynamical Processes ◽  
Triple Systems ◽  
Gravitational Problem ◽  
Three Body

The dynamical processes of formation, evolution and disruption of binaries may be effectively studied by computer simulations in the N > 3-body gravitational problem. As a result of analysis of these investigations of diverse authors, the classification of the dynamical processes of formation of wide and close binaries may be proposed (see Table 1). This Table shows the following general processes: I-triple approaches of the single bodies; II-approaches of binaries with single bodies; Ill-escape from physical triples. The actions of these processes, and kinetics of a frequency of binaries in general field were studied at the Astronomical Observatory of the Leningrad State University (1965-1988) by computer simulations in the three-body problem. More than 3.104 orbits with negative total energy E < 0 and 5.104 with E > 0 have been run on the computers. The film “Dynamical evolution of triple systems” was produced. Part I of this movie shows the evolution of the unstable non-hierarchical triplet as well as the processes of formation, evolution, and disruption of temporary wide and final close binaries inside the physical triples. Part II of film presents in detail the trajectories of the bodies on the triple approaches of “fly-by”-and of “exchange”-types. The triple approach of “fly-by”-type results often in an escape from triple as well as the formation of final close binary. The triple approach of “exchange”-type consists as a rule of a few close double approaches of bodies and rarely results in an escape from triplet, it results in formation of temporary wide binary inside triplet. Part III of movie presents the trajectories of the different-mass bodies: an escape of the minimum-mass body, the intermediate-mass body, and the maximum-mass body as well as a formation of binaries with different-mass components.

scholarly journals Statistical Properties of Solar-Type Close Binaries

2004 ◽  
Vol 191 ◽  
pp. 20-27
Author(s):  
J.-L. Halbwachs ◽  
M. Mayor ◽  
S. Udry ◽  
F. Arenou
Keyword(s):  
Binary Stars ◽  
Equal Mass ◽  
Open Clusters ◽  
Statistical Properties ◽  
Spectroscopic Binaries ◽  
Close Binary ◽  
Close Binaries ◽  
Multiple Systems ◽  
Short Period ◽  
Mass Ratios

AbstractTwo Coravel radial velocity surveys dedicated to F7-K field dwarfs and to open clusters are merged in order to investigate the statistical properties of binaries with periods up to 10 years. Thanks to the accurate trigonometric parallaxes provided by Hipparcos, an unbiased sample of spectroscopic binaries (SB) is selected. After correction for the uncertainties of the measurements, the following results are obtained: 1. The distribution of mass ratios exhibits a peak for equal-mass binaries (twins), which is higher for short-period binaries than for long-period binaries. 2. Apart from the twins, the distribution of mass ratios exhibits a broad peak from 0.2 to 0.6. 3. The orbital eccentricities of twins are slightly smaller than those of other binaries. 4. An excess of SB is observed with periods shorter than about 50 days in comparison with the Duquennoy and Mayor log-normal distribution of periods. These features suggest that close binary stars are generated by two different processes. A possible difference could come from the accretion onto the binary, for instance from a common envelope or from a circumbinary disk. Alternatively, twins could come from dynamic evolution of multiple systems. It is not clear whether the formation models are already sufficiently elaborated to reproduce our statistics.

scholarly journals Close Binary Star Observables: Modeling Innovations 2003-06

2006 ◽  
Vol 2 (S240) ◽  
pp. 188-197
Author(s):  
R. E. Wilson
Keyword(s):  
Parameter Estimation ◽  
Binary System ◽  
Binary Star ◽  
Thomson Scattering ◽  
Stellar Atmospheres ◽  
Light Curves ◽  
Close Binary ◽  
Line Profiles ◽  
Radiative Transfer Problem ◽  
Mass Ratios

AbstractInnovative work on close binary models in 2003-06 improved upon synthesized line spectra, line profiles, and polarimetry; developed new ways of parameter estimation; and increased solution effectiveness and efficiency. Recent applications demonstrate the analytic power of binary system line spectrum models that pre-date the triennium. X-ray binary line profiles and radial velocity curves were refined by solution of the radiative transfer problem with specific inclusion of X-irradiation. Model polarization curves were generated by Monte Carlo experiments with multiple Thomson scattering in thin and thick binary system disks. In the parameter estimation area, independent developments by two groups now allow measurement of ephemerides, apsidal motion, and third body parameters from whole light and velocity curves, to supplement the traditional way of eclipse timings. Although the new route to those parameters is not well known within the ephemeris community, there are accuracy advantages and the number of applications is increasing. Numerical solution experiments on photometric mass ratios have checked two views of their intuitive basis, and show that mass ratios are well determined where star radii and limiting lobe radii are both well determined, which is for semi-detached or over-contact binaries with total-annular eclipses. Solution efficiency and automatic operation is needed for processing of light curves from large surveys, and will also be valuable for preliminary solutions of individually observed binaries. Neural networks have mainly been used for classification, and now a neural network program reliably finds preliminary solutions for W UMa binaries. Archived model light curves and Fourier fitting also are being pursued for classification and for preliminary solutions. Light curves in physical units such as erg·sec−1·cm−3 now allow direct distance estimation by combining the absolute accuracy of model stellar atmospheres with the astrophysical detail of a physical close binary model, by means of rigorous scaling between surface emission and observable flux. A Temperature-distance (T-d) theorem specifies conditions under which temperatures of both stars and distance can be found from light and velocity curves.

scholarly journals A Gentle Process for the Formation of Algols

1989 ◽  
Vol 107 ◽  
pp. 369-369
Author(s):  
C. A. Tout ◽  
P. P. Eggleton
Keyword(s):  
Mass Transfer ◽  
Magnetic Fields ◽  
Mass Loss ◽  
White Dwarf ◽  
Binary Systems ◽  
Roche Lobe ◽  
Close Binary ◽  
Red Giants ◽  
Convective Envelope ◽  
Mass Ratios

AbstractThis work is concerned with binary systems that we call ‘moderately close’. These are systems in which the primary (by which we mean the initially more massive star) fills its Roche lobe when it is on the giant branch with a deep convective envelope but before helium ignition (late case B). We find that if the mass ratio q(= M1/M2) < qCrit = 0.7 when the primary fills its Roche lobe positive feedback will lead to a rapid hydrodynamic phase of mass transfer which will probably lead to common envelope evolution and thence to either coalescence or possibly to a close binary in a planetary nebula. Although most Algols have probably filled their Roche lobes before evolving off the main-sequence we find that some could not have and are therefore ‘moderately close’. Since rapid overflow is unlikely to lead to an Algol-like system there must be some way of avoiding it. The most likely possibility is that the primary can lose sufficient mass to reduce q below qcrit before overflow begins. Ordinary mass loss rates are insufficient but evidence that enhanced mass loss does take place is provided by RS CVn systems that have inverted mass ratios but have not yet begun mass transfer. We postulate that the cause of enhanced mass loss lies in the heating of the corona by by magnetic fields maintained by an α-ω dynamo which is enhanced by tidal effects associated with corotation. In order to model the the effects of enhanced mass loss we ignore the details and adopt an empirical approach calibrating a simple formula with the RS CVn system Z Her. Using further empirical relations (deduced from detailed stellar models) that describe the evolution of red giants we have investigated the effect on a large number of systems of various initial mass ratios and periods. These are notable in that some systems can now enter a much gentler Algol-like overflow phase and others are prevented from transferring mass altogether. We have also investigated the effects of enhanced angular momentum loss induced by corotation of the wind in the strong magnetic fields and consider this in relation to observed period changes. We find that a typical ‘moderately close’ Algol-like system evolves through an RS CVn like system and then possibly a symbiotic state before becoming an Algol and then goes on through a red giant-white dwarf state which may become symbiotic before ending up as a double white dwarf system in either a close or wide orbit depending on how much mass is lost before the secondary fills its Roche lobe.

scholarly journals Simulating the formation of η Carinae’s surrounding nebula through unstable triple evolution and stellar merger-induced eruption

2021 ◽  
Vol 503 (3) ◽  
pp. 4276-4296
Author(s):  
Ryosuke Hirai ◽  
Philipp Podsiadlowski ◽  
Stanley P Owocki ◽  
Fabian R N Schneider ◽  
Nathan Smith
Keyword(s):  
Massive Star ◽  
Theoretical Calculations ◽  
Strong Support ◽  
Close Binary ◽  
Triple Systems ◽  
Surrounding Structure ◽  
Mass Outflow ◽  
Key Aspects ◽  
Mass Ejection ◽  
Primary Agent

ABSTRACT η Carinae is an extraordinary massive star famous for its 19th century Great Eruption and the surrounding Homunculus nebula ejected in that event. The cause of this eruption has been the centre of a long-standing mystery. Recent observations, including light-echo spectra of the eruption, suggest that it most likely resulted from a stellar merger in an unstable triple system. Here we present a detailed set of theoretical calculations for this scenario; from the dynamics of unstable triple systems and the mass ejection from close binary encounters, to the mass outflow from the eruption caused by the stellar merger and the post-merger wind phase. In our model the bipolar post-merger wind is the primary agent for creating the Homunculus, as it sweeps up external eruption ejecta into a thin shell. Our simulations reproduce many of the key aspects of the shape and kinematics of both the Homunculus nebula and its complex surrounding structure, providing strong support for the merger-in-a-triple scenario.

A New Criterion for Classification of Flows

2003 ◽  
Author(s):  
Roney Leon Thompson ◽  
Paulo Roberto de Souza Mendes
Keyword(s):  
Relative Rate ◽  
Objective Criterion ◽  
Local Frame ◽  
Flow Classification ◽  
General Flow ◽  
Stress Relieving ◽  
Flowing Material ◽  
New Criterion ◽  
Flow Criterion

Astarita (1979) proposed a local and objective criterion to classify flows. His criterion is not restricted to MWCSH, and is essentially an attempt to quantify the stress-relieving rotation experiences by the flowing material. Huilgol (1980) analyzed Astarita’s work and showed, through examples, some inconsistencies which rendered it useless as a general flow criterion. The present work revisits Huilgol’s examples and discusses in detaile the underlying physics that mark Astarita’s criterion to fail for certain flows. This analysis leads to a new criterion for flow classification involving the concept of persistence of straining. A key kinematic entity introduced in the proposed criterion is the π-plane, a plane that is normal to the relative-rate-of-rotation vector. For a more comprehensive criterion, other parameters are needed in addition to a persistence-of-straining parameter. One of them is a measure of the deformation rate in the π-plane. Emphasis is given to isochoric motions. The proposed kinematic criterion is local, frame-different and is not restricted to particular classes of flows.

scholarly journals Triage of astrometric binaries – how to find triple systems and dormant black hole secondaries in the Gaia orbits

2019 ◽  
Vol 487 (4) ◽  
pp. 5610-5617 ◽  
Author(s):  
S Shahaf ◽  
T Mazeh ◽  
S Faigler ◽  
B Holl
Keyword(s):  
Black Hole ◽  
Semimajor Axis ◽  
Compact Object ◽  
Simple Algorithm ◽  
Close Binary ◽  
Mass Ratio ◽  
Suggested Approach ◽  
Triple Systems ◽  
Primary Mass ◽  
Astrometric Binaries

ABSTRACT Preparing for the expected wealth of Gaia detections, we consider here a simple algorithm for classifying unresolved astrometric binaries with main-sequence (MS) primary into three classes: binaries with a probable MS secondary, with two possible values for the mass ratio; probable hierarchical triple MS systems with an astrometric secondary as a close binary, with a limited range of mass-ratio values; and binaries with a compact-object secondary, with a minimal value of the mass ratio. This is done by defining a unitless observational parameter ‘Astrometric Mass-Ratio Function’ (AMRF), $\mathcal {A}$, of a binary, based on primary-mass estimation, in addition to the astrometric parameters – the angular semimajor axis, the period, and the parallax. We derive the $\mathcal {A}$ value that differentiates the three classes by forward modelling representative binaries of each class, assuming some mass–luminosity relation. To demonstrate the potential of the algorithm, we consider the orbits of 98 Hipparcos astrometric binaries with MS primaries, using the Hipparcos parallaxes and the primary-mass estimates. For systems with known spectroscopic orbital solution, our results are consistent with the spectroscopic elements, validating the suggested approach. The algorithm will be able to identify hierarchical triple systems and dormant neutron star and black hole companions in the Gaia astrometric binaries.

scholarly journals Stability and Instability of Hierarchical Triple Systems

1995 ◽  
Vol 164 ◽  
pp. 370-370 ◽  
Author(s):  
L. Kiseleva ◽  
J. Anosova ◽  
P. Eggleton ◽  
J. Colin ◽  
V. Orlov
Keyword(s):  
Initial Period ◽  
Dynamical Evolution ◽  
Limited Range ◽  
Integration Time ◽  
Small Range ◽  
Period Ratio ◽  
Triple Systems ◽  
Stability And Instability ◽  
Mass Ratios ◽  
Distant Body

We computed the dynamical evolution of hierarchical triple stars in which both orbits are initially circular, and determine the lower limit to the ratio of periods (outer/inner) for which there is dynamical stability. We found for some mass ratios resonance-like behaviour that occurs in a limited range of initial period ratio. Some resonances are ‘disruptive’; that is, for a small range of initial period ratio we find that the system is not able to settle down to a quasi-steady hierarchical state, but instead disrupts. However, below as well as above this disruptive range there are considerable ranges of initial period ratio where the hierarchical state appears to be stable, at least for the length of integration time we took which was sometimes as much as 10,000 outer orbits. The mass ratios are identified for which different types of unstable behaviour, such as an escape of the distant body without exchange, many exchanges in the limited space without escape, formation of new long-live hierarchy, or an escape of one body after a few exchanges, occur for ratios of periods slightly below the limit of stability. We discuss the relevance of the above behaviour to observed close triples, the closest of which is λ Tau (period ratio 8.3).

scholarly journals Evolutionary computations for intermediate mass close binary systems

1981 ◽  
Vol 59 ◽  
pp. 503-506
Author(s):  
Th. J. van der Linden
Keyword(s):  
Mass Transfer ◽  
Numerical Simulations ◽  
Binary Systems ◽  
Close Binary ◽  
Close Binaries ◽  
Intermediate Mass ◽  
Evolutionary Computations ◽  
Primary Mass ◽  
Close Binary Systems ◽  
Mass Ratios

AbstractNumerical simulations of the evolution of close binaries with primary mass between 3 and 15 Mʘ and mass ratios of ~ 1.5 were carried out. These results show that after mass transfer the system consists of a bright main-sequence.star together with a faint He-star in a rather wide orbit (p> 60d) Evolution of this kind predicts isotope anomalies for the CNO-elements with respect to their solar values.

scholarly journals MASS RATIOS OF LONG-PERIOD BINARY STARS RESOLVED IN PRECISION ASTROMETRY CATALOGS OF TWO EPOCHS

2021 ◽  
Vol 57 (2) ◽  
pp. 399-405
Author(s):  
Valeri V. Makarov
Keyword(s):  
Binary Stars ◽  
Center Of Mass ◽  
Physical Parameters ◽  
Triple Systems ◽  
Long Period ◽  
Mass Ratios ◽  
Space Astrometry ◽  
Estimation Of Uncertainties ◽  
External Forces ◽  
Astrometric Data

Mass ratios of widely separated, long-period, resolved binary stars can be directly estimated from the available data in major space astrometry catalogs, such as the ESA's Hipparcos and Gaia mission results. The method is based on the universal principle of inertial motion of the system's center of mass in the absence of external forces, and is independent of any assumptions about the physical parameters or stellar models. The application is limited by the precision of input astrometric data, the orbital period and distance to the system, and possible presence of other attractors in the vicinity, such as in triple systems. A generalization of this technique to triples is proposed, as well as approaches to estimation of uncertainties. The known long-period binary HIP 473 AB is discussed as an application example, for which a m2/ m1 = 0.996+0.026 −0.026 is obtained.

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