scholarly journals Birth environment of circumbinary planets: are there circumbinary planets on inclined orbits?

2020 ◽  
Vol 493 (2) ◽  
pp. 1907-1912 ◽  
Author(s):  
Chuan-Tao Ma ◽  
Yan-Xiang Gong ◽  
Xiao-Mei Wu ◽  
Jianghui Ji
Keyword(s):  
Binary Star ◽  
Outer Region ◽  
Close Binary ◽  
Close Binaries ◽  
Occurrence Rate ◽  
Single Star ◽  
Orbital Inclination ◽  
Close Encounters ◽  
Birth Environment ◽  
Circumbinary Planets

ABSTRACT The distribution of the orbital inclination angles of circumbinary planets (CBPs) is an important scientific issue, and it is of great significance for estimating the occurrence rate of CBPs and studying their formation and evolution. Although the CBPs currently discovered by the transit method are nearly coplanar, the true distribution of the inclinations of CBPs is still unknown. Previous research on CBPs has mostly regarded them as isolated binary-planet systems, without considering the birth environment of their host binaries. It is generally believed that almost all stars are born in clusters. Therefore, it is necessary to consider the effects of the close encounters of stars on CBP systems. In this paper, we discuss how the close encounters of fly-by stars affect the inclinations of CBPs. Based on extensive numerical simulations, we have found that CBPs in a close binary with a spacing of ∼0.2 au are almost unaffected by fly-by stars. Their orbits remain coplanar. However, when the spacing of the binary stars is greater than 1 au, two to three fly-bys of an intruding star can excite a considerable inclination, even for a CBP near the unstable boundary of the binary. For CBPs in the outer region, the fly-by of a single star can excite an inclination to more than 5°. In particular, CBPs in near polar or retrograde orbits can naturally form through binary–star encounters. If close binaries are born in open clusters, our simulations suggest that there may be high-inclination CBPs in binaries with a spacing >1 au.

scholarly journals Surface flux patterns on planets in circumbinary systems and potential for photosynthesis

2014 ◽  
Vol 14 (3) ◽  
pp. 465-478 ◽  
Author(s):  
Duncan H. Forgan ◽  
Alexander Mead ◽  
Charles S. Cockell ◽  
John A. Raven
Keyword(s):  
Binary Star ◽  
Surface Flux ◽  
Close Binary ◽  
Mass Motion ◽  
Single Star ◽  
Photosynthetic Organisms ◽  
Spatial And Temporal Distributions ◽  
Close Binary Star ◽  
Binary Star System ◽  
Circumbinary Planets

AbstractRecently, the Kepler Space Telescope has detected several planets in orbit around a close binary star system. These so-called circumbinary planets will experience non-trivial spatial and temporal distributions of radiative flux on their surfaces, with features not seen in their single-star orbiting counterparts. Earth-like circumbinary planets inhabited by photosynthetic organisms will be forced to adapt to these unusual flux patterns. We map the flux received by putative Earth-like planets (as a function of surface latitude/longitude and time) orbiting the binary star systems Kepler-16 and Kepler-47, two star systems which already boast circumbinary exoplanet detections. The longitudinal and latitudinal distribution of flux is sensitive to the centre-of-mass motion of the binary, and the relative orbital phases of the binary and planet. Total eclipses of the secondary by the primary, as well as partial eclipses of the primary by the secondary add an extra forcing term to the system. We also find that the patterns of darkness on the surface are equally unique. Beyond the planet's polar circles, the surface spends a significantly longer time in darkness than latitudes around the equator, due to the stars’ motions delaying the first sunrise of spring (or hastening the last sunset of autumn). In the case of Kepler-47, we also find a weak longitudinal dependence for darkness, but this effect tends to average out if considered over many orbits. In the light of these flux and darkness patterns, we consider and discuss the prospects and challenges for photosynthetic organisms, using terrestrial analogues as a guide.

scholarly journals The Impact of Large Databases on the Knowledge of Late-Type Close Binaries

2004 ◽  
Vol 191 ◽  
pp. 239-246
Author(s):  
C. Maceroni
Keyword(s):  
Binary Star ◽  
Eclipsing Binaries ◽  
Close Binary ◽  
Close Binaries ◽  
Future Space ◽  
Large Databases ◽  
Interesting Object ◽  
Close Binary Star ◽  
The Impact

AbstractThis paper presents some results of the analysis of the eclipsing binaries samples that came out as by-products of the OGLE microlensing surveys. These experiments monitored millions of stars in the direction of the galactic bulge (OGLE-I), and of the Small Magellanic Cloud (OGLE-II). Their completeness allowed the discovery of rare and interesting systems. An example is a new group of long period binaries in the SMC with presumably a giant component in contact with the critical lobe, which dominates the systemic light variation (“β -contacts”). These systems obey a period-luminosity-color relation and could be used as an auxiliary, but independent, tool for distance determination. Another very interesting object, for its implications in the studies of angular momentum loss processes by magnetic braking and of stellar activity, is the system of shortest known period with M dwarf components, discovered by OGLE-I, BW3 V38, that is the target of a spectroscopic follow-up. The perspectives for close binary star research in view of future space missions, such as COROT and Eddington are briefly discussed.

scholarly journals Doppler Imaging of Stars with Roche–Geometry

2006 ◽  
Vol 2 (S240) ◽  
pp. 587-592
Author(s):  
Zs. Kővári ◽  
J. Bartus ◽  
K. Oláh ◽  
K.G. Strassmeier ◽  
J.B. Rice ◽  
...  
Keyword(s):  
Binary Star ◽  
Real Data ◽  
Doppler Imaging ◽  
Close Binary ◽  
Close Binaries ◽  
Spherical Approximation ◽  
Close Binary Star

AbstractTests are carried out on retrieving Doppler maps from distorted stars in close binaries to estimate how Doppler imaging may be aliased by ellipticity. Maps obtained for the distorted shape are compared with the results of the simple spherical approximation, using real data of the RS CVn-type close binary star ζ Andromedae.

scholarly journals Asteroseismology of Close Binary Stars: Tides and Mass Transfer

2021 ◽  
Vol 8 ◽  
Author(s):  
Zhao Guo
Keyword(s):  
Mass Transfer ◽  
Binary Stars ◽  
Binary Systems ◽  
Binary Star ◽  
Close Binary ◽  
Close Binaries ◽  
Linear Mode ◽  
Stellar Oscillations ◽  
Theoretical Approaches ◽  
Stellar Interiors

The study of stellar oscillations allows us to infer the properties of stellar interiors. Meanwhile, fundamental parameters such as mass and radius can be obtained by studying stars in binary systems. The synergy between binarity and asteroseismology can constrain the parameter space of stellar properties and facilitate the asteroseismic inference. On the other hand, binarity also introduces additional complexities such tides and mass transfer. From an observational perspective, we briefly review the recent advances in the study of tidal effects on stellar oscillations, focusing on upper main sequence stars (F-, A-, or OB- type). The effect can be roughly divided into two categories. The first one concerns the tidally excited oscillations (TEOs) in eccentric binaries where TEOs are mostly due to resonances between dynamical tides and gravity modes of the star. TEOs appear as orbital-harmonic oscillations on top of the eccentric ellipsoidal light curve variations (the “heartbeat” feature). The second category is regarding the self-excited oscillations perturbed by static tides in circularized and synchronized close binaries. It includes the tidal deformation of the propagation cavity and its effect on eigenfrequencies, eigenfunctions, and the pulsation alignment. We list binary systems that show these two types of tidal effect and summarize the orbital and pulsation observables. We also discuss the theoretical approaches used to model these tidal oscillations and relevant complications such as non-linear mode coupling and resonance locking. Further information can be extracted from the observations of these oscillations which will improve our understanding of tides. We also discuss the effect of mass transfer, the extreme result of tides, on stellar oscillations. We bring to the readers' attention: (1) oscillating stars undergoing mass accretion (A-, F-, and OB type pulsators and white dwarfs), for which the pulsation properties may be changed significantly by accretion; (2) post-mass transfer pulsators, which have undergone a stable or unstable Roche-Lobe overflow. These pulsators have great potential in probing detailed physical processes in stellar interiors and mass transfer, as well as in studying the binary star populations.

scholarly journals The Evolution of Pre-Main Sequence Close Binaries

1980 ◽  
Vol 88 ◽  
pp. 149-153 ◽  
Author(s):  
Jon K. West ◽  
Kwan-Yu Chen
Keyword(s):  
Mass Transfer ◽  
Binary System ◽  
Total Mass ◽  
Main Sequence ◽  
Binary Star ◽  
Computer Models ◽  
Close Binary ◽  
Close Binaries ◽  
Close Binary Star ◽  
Conventional Computer

Conventional computer models of close binary star systems usually start with at least one component on the main sequence. Models of premain sequence binaries have been computed to study mass transfer (Yamasaki 1971). However no pre-main sequence computations have been published that follow the evolutionary tracks of a binary system onto the main sequence, even though some observed systems appear to be premain sequence (Field 1969). The main purpose of this investigation is the evaluation of individual close binaries with a pre-main sequence model. The evaluation will be accomplished by comparing the positions of the observed binary on the Hertzsprung-Russell diagram with the evolutionary tracks generated by the pre-main sequence model. If both components appear to have the same age and fall near the tracks of the model, then the system is possibly pre-main sequence. Eleven semidetached binaries were considered, each with a total mass between 2.5 and 6 solar masses and with a period between 0.9 and 3.4 days.

scholarly journals Structures of Binary Star Coronae

2004 ◽  
Vol 219 ◽  
pp. 199-210
Author(s):  
Nancy S. Brickhouse
Keyword(s):  
Binary Systems ◽  
Binary Star ◽  
Magnetic Loop ◽  
Close Binaries ◽  
Coronal Emission ◽  
Single Star ◽  
X Ray ◽  
Radio Studies ◽  
Show Evidence ◽  
Contact Binaries

Stellar coronae in binary star systems offer both a puzzle and an opportunity. We might expect that large magnetic loop structures on close binaries, such as RS CVn systems and contact binaries, would show evidence for interactions between the stars. While some radio studies support this scenario, there is surprisingly little evidence from EUV and X-ray observations for differences between binary and single star systems. Meanwhile, the binary systems offer observational opportunities through rotational modulation and eclipses of flaring and non-flaring regions. Localizing the sources of coronal emission is key to making the magnetic connection to the underlying photosphere. We discuss the structure of stellar coronae from the perspective of studies of binary systems.

scholarly journals Close-Binary and Pulsating Central Stars

1989 ◽  
Vol 131 ◽  
pp. 251-260
Author(s):  
Howard E. Bond
Keyword(s):  
Binary Star ◽  
Cataclysmic Variables ◽  
Close Binary ◽  
Close Binaries ◽  
Order Of Magnitude ◽  
Orbital Periods ◽  
Red Giant ◽  
Photometric Monitoring ◽  
Significant Production ◽  
Central Stars

As a result of photometric-monitoring studies, 7 planetary-nebula nuclei are now known to be binaries with orbital periods less than one day. These systems were probably produced via a common-envelope interaction, during which a wide pair was converted to a close binary surrounded by an ejected red-giant envelope. The frequency of occurrence of such close binaries among PNNs is about 10–15%, showing that binary-star interactions are a significant production mechanism for planetary nebulae. The descendants of close-binary PNNs are probably the cataclysmic variables. Two CVs surrounded by nebulae resembling old planetaries, 0623+71 and GK Per, may provide the most direct evidence for the origin of CVs through PN ejection. The observed birth rate for close-binary PNNs is more than an order of magnitude higher than for CVs, possibly indicating that our census of the CV population is very incomplete. The nucleus of K 1-16 is a member of the GW Vir class of extremely hot pulsating pre-white dwarfs, and the only one known to be surrounded by a PN. These objects offer exciting opportunities for direct measurement of evolutionary timescales and for seismological investigations of the interiors of PNNs and their immediate descendants.

scholarly journals The implications of close binary stars for star-disk interactions

2007 ◽  
Vol 3 (S243) ◽  
pp. 315-324 ◽  
Author(s):  
Robert D. Mathieu
Keyword(s):  
Binary Stars ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Close Binary ◽  
Close Binaries ◽  
Spectral Energy ◽  
Stellar Rotation ◽  
Single Star ◽  
Accretion Flows ◽  
T Tauri

AbstractThe presence of close (≲ 0.1 AU) stellar companions must greatly alter the circumstellar environment of classical T Tauri stars, including severe truncation if not elimination of circumstellar disks. It is thus remarkable how little impact the presence of a close companion has on our observable diagnostics for accretion and outflow. Emission line shapes, degrees of continuum veiling, and spectral energy distributions are all indistinguishable between single classical T Tauri stars and classical T Tauri close binaries. Some of the most classical T Tauri stars that laid the foundation for our single-star accretion-disk paradigm have turned out to have close companions. Periodicities in spectral signatures are suggestive of the presence of accretion flows from circumbinary disks to the circumstellar regions; the subsequent flow of material through the circumstellar region to the stellar surface in the presence of a stellar magnetosphere is unstudied. Observations of stellar rotation distributions in close binaries suggest that inner disk regions may act to regulate stellar angular momentum.

scholarly journals Effects of flux variation on the surface temperatures of Earth-analog circumbinary planets

2020 ◽  
Vol 499 (1) ◽  
pp. 1506-1521
Author(s):  
S Karthik Yadavalli ◽  
Billy Quarles ◽  
Gongjie Li ◽  
Nader Haghighipour
Keyword(s):  
Differential Evolution ◽  
Surface Temperature ◽  
Binary Star ◽  
Balance Model ◽  
Flux Variation ◽  
Short Term ◽  
Dynamical Mass ◽  
Single Star ◽  
Hypothetical System ◽  
Circumbinary Planets

ABSTRACT The Kepler Space telescope has uncovered around thirteen circumbinary planets (CBPs) that orbit a pair of stars and experience two sources of stellar flux. We characterize the top-of-atmosphere flux and surface temperature evolution in relation to the orbital short-term dynamics between the central binary star and an Earth-analog CBP. We compare the differential evolution of an Earth-analog CBP’s flux and surface temperature with that of an equivalent single-star (ESS) system to uncover the degree by which the potential habitability of the planet could vary. For a Sun-like primary, we find that the flux variation over a single planetary orbit is greatest when the dynamical mass ratio is $\sim$0.3 for a G-K spectral binary. Using a latitudinal energy balance model, we show that the ice-albedo feedback plays a substantial role in (Earth-analog) CBP habitability due to the interplay between flux redistribution (via obliquity) and changes in the total flux (via binary gyration). We examine the differential evolution of flux and surface temperature for Earth-like analogs of the habitable zone CBPs (4 Kepler and 1 hypothetical system) and find that these analogs are typically warmer than their ESS counterparts.

scholarly journals Magnetic field generation in an accretion disk of close binary star

2012 ◽  
Vol 8 (S294) ◽  
pp. 187-192
Author(s):  
Dmitry V. Bisikalo ◽  
Andrey G. Zhilkin
Keyword(s):  
Magnetic Field ◽  
Numerical Simulations ◽  
Accretion Disk ◽  
Binary Star ◽  
Outer Region ◽  
Close Binary ◽  
Magnetic Field Generation ◽  
Field Generation ◽  
Close Binary Star ◽  
The Magnetic Field

AbstractUsing results of 3D MHD numerical simulations we investigate the generation of the magnetic field in an accretion disk of a close binary star. Analysis of the numerical simulations shows that the magnetic field, which is mainly toroidal, is intensively generated in the accretion disk. In the disk, we can distinguish three regions: inner region of the intensive toroidal field generation due to the differential rotation; region of the current sheets; and outer region of the magnetic field dissipation. In the outer regions of the accretion disk of a magnetic close binary system two types of the dynamo may exist. One of them is the laminar dynamo that occurs as a result of the nonaxisymmetric motions. The other type is the turbulent αω-dynamo. Numerical simulations show that during the disk lifetime the dynamo effect in the outer region of the disk can be significant.

Sign in / Sign up

Export Citation Format

Share Document