scholarly journals Angular Momentum Loss and Transfer in Close Binaries: Effects on a Human Time-Scale?

1998 ◽  
Vol 11 (1) ◽  
pp. 353-353
Author(s):  
C. Maceroni
Keyword(s):  
Angular Momentum ◽  
Orbital Period ◽  
Dynamical Evolution ◽  
Cumulative Effect ◽  
Great Accuracy ◽  
Close Binaries ◽  
Late Type ◽  
Secular Evolution ◽  
Evolutionary Changes ◽  
Orbital Periods

The orbital periods of binaries are known to great accuracy, their changes produce an easily detectable cumulative effect and many systems have been observed for more than a century. In tidually locked late-type binaries the orbital period changes are often related to structural or evolutionary changes. The study of the orbital period secular evolution can therefore provide information on phenomena taking place on timescales very short when compared to the typical stellar evolutionary scales, but still much longer thant the human lifetime. This paper focuses on the dynamical evolution due to magnetic braking in late-type close binaries and on the detectability of angular momentum transfer among the stellar layers.

scholarly journals The Cumulative Effect of Stellar Encounters on Multi-Planet Systems in Star Clusters

2012 ◽  
Vol 8 (S293) ◽  
pp. 171-173
Author(s):  
Wei Hao ◽  
M. B. N. Kouwenhoven
Keyword(s):  
Planetary System ◽  
Star Clusters ◽  
Planetary Systems ◽  
Dynamical Evolution ◽  
Cumulative Effect ◽  
Star Cluster ◽  
Secular Evolution ◽  
Perturbed System ◽  
Orbital Periods

AbstractDistant stellar encouters can substantially affect the dynamical evolution of existing stellar and planetary systems (e.g., Malmberg et al. 2007; Spurzem et al. 2009). Although planets with small orbital periods are not directly affected by encountering stars, the secular evolution of a perturbed system may result in the ejection of the innermost planets, or physical collisions between the innermost planets and the host star, hundreds of thousands of years after a weak encounter with a neighboring star occurs. Here we present the results of our study on the cumulative effect of distant stellar encounters on multi-planet systems in star clusters, and how these results depend on the properties of the star cluster in which a planetary system is born (for details we refer to Hao & Kouwenhoven, in prep.). With our simulations we explain the scarcity of exoplanets in star clusters, not only for those in wide orbits (affected by stellar encounters), but also in close orbits (affected by the secular evolution of the system following an encounter).

scholarly journals Changing-look active galactic nuclei: close binaries of supermassive black holes in action

2020 ◽  
Vol 643 ◽  
pp. L9
Author(s):  
Jian-Min Wang ◽  
Edi Bon
Keyword(s):  
Black Holes ◽  
Angular Momentum ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Extreme Case ◽  
Supermassive Black Holes ◽  
Close Binaries ◽  
Orbital Periods

Changing-look active galactic nuclei (CL-AGNs) as a new subpopulation challenge some fundamental physics of AGNs because the timescales of the phenomenon can hardly be reconciled with accretion disk models. In this Letter, we demonstrate the extreme case: close binaries of supermassive black holes (CB-SMBHs) with high eccentricities are able to trigger the CL transition through one orbit. In this scenario, binary black holes build up their own mini-disks by peeling gas off the inner edges of the circumbinary disk during the apastron phase, after which they tidally interact with the disks during the periastron phase to efficiently exchange angular momentum within one orbital period. For mini-disks rotating retrograde to the orbit, the tidal torque rapidly squeezes the tidal parts of the mini-disks into a much smaller radius, which rapidly results in higher accretion and short flares before the disks decline into type-2 AGNs. Prograde-rotation mini-disks gain angular momentum from the binary and rotate outward, which causes a rapid turn-off from type-1 to type-2. Turn-on occurs around the apastron phase. CB-SMBHs control cycle transitions between type-1 and type-2 with orbital periods but allow diverse properties in CL-AGN light curves.

scholarly journals The Braking Law of Solar Type Stars as Derived from Close Binary Dynamical Evolution

1993 ◽  
Vol 137 ◽  
pp. 374-376 ◽  
Author(s):  
Carla Maceroni
Keyword(s):  
Angular Momentum ◽  
Orbital Period ◽  
Dynamical Evolution ◽  
Close Binary System ◽  
Rigid Bodies ◽  
Close Binary ◽  
Typical Result ◽  
Stiff Ordinary Differential Equations ◽  
Solar Type ◽  
Evolution Function

The orbital period of a close binary system (P ~ a few days), formed by two solar type components, evolves under the influence of angular momentum loss (AML) by electromagnetic braking and of spin↔orbit angular momentum transfer (AMT) by tidal coupling. Because of AMT, which tends to reestablish the spin-orbit synchronization destroyed by AML, the loss of AM takes finally place at the expenses of the orbital reservoir and produces shrinking of the orbit and spinning-up of the components. The variation with time of wK and w, respectively the orbital and the rotational angular velocity, is expressed by a system of (stiff) ordinary differential equations and the results of the (numerical) integration strongly depend on the AML and AMT laws. A series of recent papers (Maceroni and Van ’t Veer 1991, 1992, Van’t Veer and Macerord 1992, hereafter MVI, MV2 and VM) presents the resulting orbital period evolution function (PEF) with a variety of choices. A typical result, in terms of orbital period, and for a binary formed by two identical G5 V components, is shown in fig. IA. The solution shown here corresponds to the braking law a) of fig. IB, to the AMT according to Zahn (1977) and to stars rotating as rigid bodies; different assumptions have been tried in MVland VM.

scholarly journals J-, H-, and K-band Spectra of Three SU UMa-Type Dwarf Novae

2006 ◽  
Vol 2 (S240) ◽  
pp. 547-549
Author(s):  
Ryoko Ishioka ◽  
Kazuhiro Sekiguchi ◽  
Hiroyuki Maehara
Keyword(s):  
Orbital Period ◽  
Spectral Features ◽  
Late Type ◽  
Power Law Distribution ◽  
Dwarf Novae ◽  
Evolutionary Path ◽  
Secondary Star ◽  
Orbital Periods ◽  
Band Spectra ◽  
Absorption Features

AbstractWe present the results of J-, H-, and K-band spectroscopy on three SU UMa-type dwarf novae with orbital periods of 1.33 – 1.37 hr. We performed the SED fitting for the obtained spectra by assuming a power-law distribution for the accretion disk and using template spectra of late-type dwarfs for secondary star. ASAS 002511+1217.2 and EQ J183926+260409 are WZ Sge-type or WX Cet-type dwarf novae. We found strong water absorption features in their spectra, which are characteristic in late M- or L-type dwarfs. The SED fitting suggests that their secondary contributions to the overall SED are less than one third. We identified the secondary stars as M9 and L1 type dwarfs, which are rather less massive but still normal stars. The spectrum of SDSS J013701−091235 is dominated by the secondary component. Spectral features of this object are similar to those of an early M-type dwarf in spite of its short orbital period. The spectrum of SDSS 0137 strongly suggests that the evolutionary path of this object is different from that of ordinary CVs, and this object is a candidate of EI Psc-like systems.

scholarly journals Secular period decreasing of 17 detached chromospherically active binaries

2008 ◽  
Vol 4 (S252) ◽  
pp. 437-438
Author(s):  
C. Q. Luo ◽  
Y. P. Luo ◽  
X. B. Zhang ◽  
L. C. Deng ◽  
Z. Q. Luo ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Period ◽  
Close Binaries ◽  
Momentum Loss ◽  
System A ◽  
Angular Momentum Loss ◽  
Theoretical Predictions

AbstractThe long-term orbital period changes of detached chromospheric active binaries were surveyed. 17 of such systems are found to be undergoing secular period decreasing with the rates (dP/dt) of −3.05 × 10−9 to −3.77 × 10−5 days per year. The longer the orbital period, the more rapidly the period decreases. Following Stepien (1995), the period decreasing rate due to the angular momentum loss (AML) caused by magnetic wind is computed for each system. A comparison shows that the observed dP/dt's are obviously higher than that of the theoretical predictions by 1-3 orders of magnitude. It suggests that the magnetic wind is not likely the determinant mechanism driving the AML in close binaries.

Origin of Very-Short Orbital-Period Binary Systems

1983 ◽  
Vol 72 ◽  
pp. 263-267
Author(s):  
Shigeki Miyaji
Keyword(s):  
Binary System ◽  
Globular Cluster ◽  
Orbital Period ◽  
Binary Systems ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Close Binaries ◽  
X Ray ◽  
Evolutionary Scenario ◽  
Orbital Periods

Recent observations of four close binaries have established that there is a group of very-short orbital-period (VSOP) binaries whose orbital periods are less than 60 minutes. The VSOP binaries consist of both x-ray close binaries (4U1626-67; Middleditch et al. 1981 and 4U1916 -0.5; White and Swank 1982) and cataclysmic variables (AM CVn; Faulkner et al. 1972 and G61-29; Nather et al. 1981). Their orbital periods are too short to have a main-sequence companion. However, four binaries, none of them belongs to any globular cluster, are too abundant to be explained by capturing mechanism of a white dwarf. Therefore it seemed to be worth to present an evolutionary scenario from an original binary system which can be applied for all of VSOP binaries.

scholarly journals A census of main-sequence interactions in the Multiple Star Catalogue

2020 ◽  
Vol 494 (4) ◽  
pp. 5298-5313 ◽  
Author(s):  
Adrian S Hamers
Keyword(s):  
Main Sequence ◽  
Dynamical Evolution ◽  
Dynamical Instability ◽  
Strong Interactions ◽  
Hierarchical Systems ◽  
Multiple Star ◽  
Additional Information ◽  
Secular Evolution ◽  
Star Catalogue ◽  
Orbital Periods

ABSTRACT Statistics of hierarchical systems containing three or more stars are continuously improving. The Multiple Star Catalogue (MSC) is currently the most comprehensive catalogue of multiple-star systems and contains component masses, orbital periods, and additional information. The systems in the MSC are interesting for several reasons, including the long-term dynamical evolution of few-body systems. Although the secular evolution of triples and quadruples has been explored before, a systematic study of the systems in the MSC including also quintuples and sextuples has not been carried out. Here, we explore the main-sequence (MS) evolution of stars from the MSC based on approximately 2 × 105 secular dynamical integrations. We estimate statistical probabilities for strong interactions during the MS such as tidal evolution and mass transfer, and the onset of dynamical instability. Depending on the assumed model for the unknown orbital elements, we find that the fraction of non-interacting systems is largest for triples (∼0.9), and decreases to ∼0.6–0.8 for sextuples. The fraction of strong interactions increases from ∼0.1 to ∼0.2 from triples to sextuples, and the fraction of dynamically unstable systems increases from ∼0.001 to ∼0.1–0.2. The larger fractions of strong interactions and dynamical instability in systems with increasing multiplicity can be attributed to increasingly complex secular evolution in these systems. Our results indicate that a significant fraction of high-multiplicity systems interact or become dynamically unstable already during the MS, with an increasing importance as the number of stars increases.

scholarly journals A Limit on the Space Density of Short-Period Binary White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 492-497
Author(s):  
Edward L. Robinson ◽  
Allen W. Shafter
Keyword(s):  
Orbital Period ◽  
Binary Stars ◽  
White Dwarfs ◽  
Main Sequence ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Space Density ◽  
Short Period ◽  
Hot Subdwarfs ◽  
Orbital Periods

We infer that detached binary white dwarfs with orbital periods of a few hours exist because we observe both their progenitors and their descendents. The binary LB 3459 has an orbital period of 6.3 hr and contains a pair of hot subdwarfs that will eventually cool to become white dwarfs (Kilkenny, Hill, and Penfold 1981). L870-2 is a pair of white dwarfs and, given enough time, its 1.55 d orbital period will decay to shorter periods (Saffer, Liebert, and Olszewski 1988). GP Com, AM CVn, V803 Cen, and PG1346+082 are interacting binary white dwarfs with orbital periods between 1051 s for AM CVn and 46.5 min for GP Com (Nather, Robinson, and Stover 1981; Solheim et al. 1984; Wood et al. 1987; O’Donoghue and Kilkenny 1988). These ultrashort period systems must be descendents of detached pairs of white dwarfs. We also expect short-period binary white dwarfs to exist for theoretical reasons. All calculations of the evolution of binary stars show that main-sequence binaries can evolve to binary white dwarfs (e.g., Iben and Tutukov 1984). Among Population I stars, 1/2 to 2/3 of all main-sequence stars are binaries and about 20% of these binaries should become double white dwarfs with short orbital periods (Abt 1983, Iben and Tutukov 1986). Thus, about 1/10 of all white dwarfs could be close binaries (Paczynski 1985). Nevertheless, no detached binary white dwarfs with extremely short periods have yet been found.

scholarly journals Periods of Unevolved Late-Type Close Binaries: Evidence of Magnetic Activity

1983 ◽  
Vol 71 ◽  
pp. 391-392
Author(s):  
G. Giuricin ◽  
S. Catalano ◽  
F. Mardirossian ◽  
M. Mezzetti
Keyword(s):  
Angular Momentum ◽  
Orbital Angular Momentum ◽  
Stellar Wind ◽  
Magnetic Activity ◽  
Close Binaries ◽  
Late Type ◽  
Period Distribution ◽  
Short Period ◽  
Angular Momentum Loss ◽  
Magnetic Braking

ABSTRACTOur study of the period distribution of about 200 FGKM-type unevolved close binaries has revealed a strong deficit of short-period systems.This finding may be connected with the occurrence of a very efficient mechanism of orbital angular momentum loss via magnetic braking by stellar wind, in the earliest evolutionary phases.

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