Orbital stability of S-type circumbinary planets

Abstract Nowadays, more than 4,000 exoplanets have been discovered, including a hundred of circumbinary planets. In the following work, the orbital variations of 67 S-type circumbinary planets have been studied. Their orbital evolutions for a thousand years are simulated using the REBOUND package. The published physical and orbital parameters of the systems are used to computed the systems’ orbital instability limits: Roche limit and Hill’s sphere. From 67 systems, there are two unstable circumbinary systems: Kepler-420 and GJ 86. Kepler-420 Ab orbit passes into the system’s Roche limit due to its high orbital eccentricity. For GJ 86 Ab, the planet orbits outside its Hill’s sphere. The instability of GJ 86 Ab might be caused by an inaccurate measurement of GJ 86 A physical parameters. Using the GJ 86 A mass obtained from Farihi et al., the planet orbits in the stable orbit zone.

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The wind-wind collision hole in eta Car

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317002630 ◽

2016 ◽

Vol 12 (S329) ◽

pp. 186-190

Author(s):

A. Damineli ◽

M. Teodoro ◽

N. D. Richardson ◽

T. R. Gull ◽

M. F. Corcoran ◽

...

Keyword(s):

Light Curve ◽

Accurate Determination ◽

Physical Parameters ◽

Electromagnetic Spectrum ◽

Orbital Eccentricity ◽

Orbital Parameters ◽

Eta Carinae ◽

Secondary Star ◽

Reflected Light

AbstractEta Carinae is one of the most massive observable binaries. Yet determination of its orbital and physical parameters is hampered by obscuring winds. However the effects of the strong, colliding winds changes with phase due to the high orbital eccentricity. We wanted to improve measures of the orbital parameters and to determine the mechanisms that produce the relatively brief, phase-locked minimum as detected throughout the electromagnetic spectrum. We conducted intense monitoring of the He ii λ4686 line in η Carinae for 10 months in the year 2014, gathering ~300 high S/N spectra with ground- and space-based telescopes. We also used published spectra at the FOS4 SE polar region of the Homunculus, which views the minimum from a different direction. We used a model in which the He ii λ4686 emission is produced by two mechanisms: a) one linked to the intensity of the wind-wind collision which occurs along the whole orbit and is proportional to the inverse square of the separation between the companion stars; and b) the other produced by the ‘bore hole’ effect which occurs at phases across the periastron passage. The opacity (computed from 3D SPH simulations) as convolved with the emission reproduces the behavior of equivalent widths both for direct and reflected light. Our main results are: a) a demonstration that the He ii λ4686 light curve is exquisitely repeatable from cycle to cycle, contrary to previous claims for large changes; b) an accurate determination of the longitude of periastron, indicating that the secondary star is ‘behind’ the primary at periastron, a dispute extended over the past decade; c) a determination of the time of periastron passage, at ~4 days after the onset of the deep light curve minimum; and d) show that the minimum is simultaneous for observers at different lines of sight, indicating that it is not caused by an eclipse of the secondary star, but rather by the immersion of the wind-wind collision interior to the inner wind of the primary.

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Twin stars as tracers of binary evolution in the Kepler era

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab343 ◽

2021 ◽

Author(s):

Sara Bulut ◽

Baris Hoyman ◽

Ahmet Dervisoglu ◽

Orkun Özdarcan ◽

Ömür Cakilrli

Keyword(s):

High Resolution ◽

Internal Structure ◽

Spectroscopic Analysis ◽

Independent Method ◽

Eclipsing Binaries ◽

Physical Parameters ◽

Evolutionary Status ◽

Mass Ratio ◽

Orbital Parameters ◽

Binary Evolution

Abstract We present results of the combined photometric and spectroscopic analysis of four systems, which are eclipsing binaries with a twin–component (mass ratio q ≃ 1). These are exceptional tools to provide information for probing the internal structure of stars. None of the systems were previously recognized as twin binaries. We used a number of high–resolution optical spectra to calculate the radial velocities and later combined them with photometry to derive orbital parameters. Temperatures and metallicities of systems were estimated from high-resolution spectra. For each binary, we obtained a full set of orbital and physical parameters, reaching precision below 3 per cent in masses and radii for whole pairs. By comparing our results with PARSEC and MIST isochrones, we assess the distance, age and evolutionary status of the researched objects. The primary and/or secondary stars of EPIC 216075815 and EPIC 202843107 are one of the cases where asteroseismic parameters of δ Sct and γ Dor pulsators were confirmed by an independent method and rare examples of the twin–eclipsing binaries, therefore the following analyses and results concern the pulsating nature of the components.

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Tidal evolution of circumbinary systems with arbitrary eccentricities: applications for Kepler systems

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937248 ◽

2020 ◽

Vol 634 ◽

pp. A12

Author(s):

F. A. Zoppetti ◽

A. M. Leiva ◽

C. Beaugé

Keyword(s):

Time Lag ◽

Semimajor Axis ◽

Tidal Flow ◽

Orbital Evolution ◽

Axis Ratio ◽

Tidal Evolution ◽

Tidal Interactions ◽

Orbital Instability ◽

Outward Migration ◽

Circumbinary Planets

We present an extended version of the Constant Time Lag analytical approach for the tidal evolution of circumbinary planets introduced in our previous work. The model is self-consistent, in the sense that all tidal interactions between pairs are computed, regardless of their size. We derive analytical expressions for the variational equations governing the spin and orbital evolution, which are expressed as high-order elliptical expansions in the semimajor axis ratio but retain closed form in terms of the binary and planetary eccentricities. These are found to reproduce the results of the numerical simulations with arbitrary eccentricities very well, as well as reducing to our previous results in the low-eccentric case. Our model is then applied to the well-characterised Kepler circumbinary systems by analysing the tidal timescales and unveiling the tidal flow around each different system. In all cases we find that the spins reach stationary values much faster than the characteristic timescale of the orbital evolution, indicating that all Kepler circumbinary planets are expected to be in a sub-synchronous state. On the other hand, all systems are located in a tidal flow leading to outward migration; thus the proximity of the planets to the orbital instability limit may have been even greater in the past. Additionally, Kepler systems may have suffered a significant tidally induced eccentricity damping, which may be related to their proximity to the capture eccentricity. To help understand the predictions of our model, we also offer a simple geometrical interpretation of our results.

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New Orbits for Enceladus and Dione Based on the Photographic Observations

International Astronomical Union Colloquium ◽

10.1017/s0252921100062333 ◽

1978 ◽

Vol 41 ◽

pp. 239-239

Author(s):

W.H. Jefferys ◽

J.D. Mulholland ◽

L.M. Ries

Keyword(s):

Gravitational Field ◽

Computer Software ◽

Physical Parameters ◽

Theoretical Studies ◽

Orbital Theory ◽

Orbital Parameters ◽

Outer Planets ◽

Computer Software System ◽

Near Future ◽

Orbit Problem

AbstractA program is underway at the McDonald Observatory to extend the series of photographic observations of the satellites of the outer planets (Abbot, Mulholland and Shelus, A.J. 80, 1975), and concurrent theoretical studies have led to a new orbital theory for the resonant pair of satellites, Enceladus and Dione (Jefferys and Ries, A.J. 80, 1975). The construction of the new theory, using the computer software system TRIGMAN, has provided Fortran subroutines for the computation of the planetocentric coordinates of the two satellites, as well as partial derivatives for the orbit elements and certain other physical parameters of the orbit problem, including some of the harmonics of the gravitational field of Saturn. The available photographic observations for these two objects are currently being discussed with the new theory, and improved values of the orbital parameters are expected in the near future.

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Planets in Double Stars: The ϒ Cephei System

International Astronomical Union Colloquium ◽

10.1017/s0252921100008800 ◽

2004 ◽

Vol 191 ◽

pp. 222-226 ◽

Cited By ~ 4

Author(s):

R. Dvorak ◽

E. Pilat-Lohinger ◽

E. Bois ◽

B. Funk ◽

F. Freistetter ◽

...

Keyword(s):

Solar System ◽

The Sun ◽

Stable Orbit ◽

Orbital Parameters ◽

Double Stars ◽

The Stability

AbstractUp to now we have evidence for some 15 planets moving in double stars. They are all of the so-called S-type, which means that they are orbiting one of the primaries. Only two of the binaries have separations in the order of the distances where the planets in our Solar system orbit the Sun, namely Gliese 86 and ϒ Cep. In this study we investigate the stability of the recently discovered planet in ϒ Cep with respect to the orbital parameters of the binary and of the planet. Additionally we check the region inside and outside the planet’s orbit (a = 2.1 AU). Even when the mass of an additional planet in 1 AU would be in the order of that of Jupiter, the discovered planet would be in a stable orbit.

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HADES RV program with HARPS-N at the TNG

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834868 ◽

2019 ◽

Vol 622 ◽

pp. A193 ◽

Cited By ~ 10

Author(s):

L. Affer ◽

M. Damasso ◽

G. Micela ◽

E. Poretti ◽

G. Scandariato ◽

...

Keyword(s):

Rotation Period ◽

Activity Cycle ◽

Physical Parameters ◽

Correlated Noise ◽

Minimum Mass ◽

Stellar Rotation ◽

Orbital Parameters ◽

Photometric Observations ◽

Depth Analysis ◽

Low Mass

Aims. The HArps-n red Dwarf Exoplanet Survey (HADES) is providing a major contribution to the widening of the current statistics of low-mass planets, through the in-depth analysis of precise radial-velocity (RV) measurements in a narrow range of spectral sub-types. Using the HARPS-N spectrograph we reach the precision needed to detect small planets with a few earth masses. Our survey is mainly focused on the M-dwarf population of the northern hemisphere. Methods. As part of that program, we obtained RV measurements of Gl 686, an M1 dwarf at d = 8.2 pc. These measurements show a dispersion much in excess of their internal errors. The analysis of data obtained within an intensive observing campaign demonstrates that the excess dispersion is due to a coherent signal with a period of 15.53 d. Almost simultaneous photometric observations were carried out within the APACHE and EXORAP programs to characterize the stellar activity and to distinguish periodic variations related to activity from signals due to the presence of planetary companions, complemented also with ASAS photometric data. We used a Bayesian framework to estimate the orbital parameters and the planet minimum mass, and to properly treat the activity noise. We took advantage of the available RV measurements for this target from other observing campaigns. The analysis of the RV composite time series from the HIRES, HARPS, and HARPS-N spectrographs, consisting of 198 measurements taken over 20 yr, enabled us to address the nature of periodic signals and also to characterize stellar physical parameters (mass, temperature, and rotation). Results. We report the discovery of a super-Earth orbiting at a distance of 0.092 AU from the host star Gl 686. The planet has a minimum mass of 7.1 ± 0.9 M⊕ and an orbital period of 15.532 ± 0.002 d. The analysis of the activity indexes, of the correlated noise through a Gaussian process framework, and of the photometry provides an estimate of the stellar rotation period at 37 d, and highlights the variability of the spot configuration during the long timespan covering 20 yr. The observed periodicities around 2000 d likely point to the existence of an activity cycle.

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Orbital stability of solitary waves for the generalized long-short wave resonance equations with a cubic-quintic strong nonlinear term

Journal of Inequalities and Applications ◽

10.1186/s13660-020-02505-7 ◽

2020 ◽

Vol 2020 (1) ◽

Author(s):

Xiaoxiao Zheng ◽

Huafei Di ◽

Xiaoming Peng

Keyword(s):

Solitary Waves ◽

Nonlinear Term ◽

Orbital Stability ◽

Short Wave ◽

Extended Version ◽

Gamma Delta ◽

Wave Resonance ◽

Stability Of Solitary Waves ◽

Orbital Instability ◽

Stability Results

Abstract In this paper, we investigate the orbital stability of solitary waves for the following generalized long-short wave resonance equations of Hamiltonian form: $$ \textstyle\begin{cases} iu_{t}+u_{{xx}}=\alpha uv+\gamma \vert u \vert ^{2}u+\delta \vert u \vert ^{4}u, \\ v_{t}+\beta \vert u \vert ^{2}_{x}=0. \end{cases} $$ { i u t + u x x = α u v + γ | u | 2 u + δ | u | 4 u , v t + β | u | x 2 = 0 . We first obtain explicit exact solitary waves for Eqs. (0.1). Second, by applying the extended version of the classical orbital stability theory presented by Grillakis et al., the approach proposed by Bona et al., and spectral analysis, we obtain general results to judge orbital stability of solitary waves. We finally discuss the explicit expression of $\det (d^{\prime \prime })$ det ( d ″ ) in three cases and provide specific orbital stability results for solitary waves. Especially, we can get the results obtained by Guo and Chen with parameters $\alpha =1$ α = 1 , $\beta =-1$ β = − 1 , and $\delta =0$ δ = 0 . Moreover, we can obtain the orbital stability of solitary waves for the classical long-short wave equation with $\gamma =\delta =0$ γ = δ = 0 and the orbital instability results for the nonlinear Schrödinger equation with $\beta =0$ β = 0 .

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The supergiant O + O binary system HD 166734: a new study

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317003313 ◽

2016 ◽

Vol 12 (S329) ◽

pp. 402-402 ◽

Cited By ~ 1

Author(s):

E. Gosset ◽

L. Mahy ◽

Y. Damerdji ◽

C. Nitschelm ◽

H. Sana ◽

...

Keyword(s):

Binary System ◽

Light Curve ◽

Radial Velocity ◽

Velocity Curve ◽

Physical Parameters ◽

Radial Velocity Curve ◽

X Ray ◽

Orbital Parameters

AbstractWe present here a modern study of the radial velocity curve and of the photometric light curve of the very interesting supergiant O7.5If + O9I(f) binary system HD 166734. The physical parameters of the stars and the orbital parameters are carefully determined. We also perform the analysis of the observed X-ray light curve of this colliding-wind binary.

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Extremely peculiar spectrum of the primary component of the eclipsing binary HD 66051

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319009190 ◽

2019 ◽

Vol 15 (S350) ◽

pp. 412-414

Author(s):

E. Niemczura ◽

P. A. Kołaczek-Szymański ◽

F. Castelli ◽

S. Hubrig ◽

S. P. Järvinen ◽

...

Keyword(s):

Time Series ◽

Time Series Data ◽

Primary Component ◽

Series Data ◽

Physical Parameters ◽

Orbital Parameters ◽

Chemically Peculiar ◽

Peculiar Stars ◽

Chemically Peculiar Stars ◽

Chemical Peculiarity

AbstractHD 66051 is an eclipsing and spectroscopic double-lined binary (SB2), hosting two chemically peculiar stars: a highly peculiar B star as primary and an Am star as secondary. The investigation of the new high-resolution UVES spectrum of HD 66051 allowed us to decide on the chemical peculiarity type of both components with more reliability. An analysis of TESS photometric time series data will further specify the physical parameters of the stars and the orbital parameters of the system.

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Semidetached double-lined eclipsing binaries: Stellar parameters and rare classes

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3363 ◽

2019 ◽

Vol 491 (4) ◽

pp. 5489-5497 ◽

Cited By ~ 1

Author(s):

Oleg Yu Malkov

Keyword(s):

Radial Velocity ◽

Velocity Curve ◽

Eclipsing Binaries ◽

Physical Parameters ◽

Radial Velocity Curve ◽

Orbital Parameters ◽

Comprehensive List ◽

Use Of Data ◽

Rare Classes

ABSTRACT Semidetached eclipsing systems provide a unique opportunity to derive the basic properties of interacting binaries. The goal of this work is to collect and to make use of data on semidetached systems with available light and radial velocity curve solutions. I have compiled the most comprehensive list to date, of 119 semidetached double-lined eclipsing binaries, containing the orbital parameters and physical parameters of the components. I consider the classification of semidetached binaries and discuss gaps between various classes in the Hertzspung–Russell diagram. I list systems with component parameters that are inverted and briefly discuss their evolutionary state.

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