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Frederic A Rasio - One of the best experts on this subject based on the ideXlab platform.
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extreme Orbital Evolution from hierarchical secular coupling of two giant planets
The Astrophysical Journal, 2013Co-Authors: Jean Teyssandier, Smadar Naoz, Ian Lizarraga, Frederic A RasioAbstract:Observations of exoplanets over the last two decades have revealed a new class of Jupiter-size planets with Orbital periods of a few days, the so-called hot Jupiters. Recent measurements using the Rossiter-McLaughlin effect have shown that many (∼50%) of these planets are misaligned; furthermore, some (∼15%) are even retrograde with respect to the stellar spin axis. Motivated by these observations, we explore the possibility of forming retrograde orbits in hierarchical triple configurations consisting of a star-planet inner pair with another giant planet, or brown dwarf, in a much wider orbit. Recently, it was shown that in such a system, the inner planet's orbit can flip back and forth from prograde to retrograde and can also reach extremely high eccentricities. Here we map a significant part of the parameter space of dynamical outcomes for these systems. We derive strong constraints on the Orbital configurations for the outer perturber (the tertiary) that could lead to the formation of hot Jupiters with misaligned or retrograde orbits. We focus only on the secular Evolution, neglecting other dynamical effects such as mean-motion resonances, as well as all dissipative forces. For example, with an inner Jupiter-like planet initially on a nearly circular orbit at 5 AU, we show that a misaligned hot Jupiter is likely to be formed in the presence of a more massive planetary companion (>2 MJ ) within ∼140 AU of the inner system, with mutual inclination >50° and eccentricity above ∼0.25. This is in striking contrast to the test particle approximation, where an almost perpendicular configuration can still cause large-eccentricity excitations, but flips of an inner Jupiter-like planet are much less likely to occur. The constraints we derive can be used to guide future observations and, in particular, searches for more distant companions in systems containing a hot Jupiter. © 2013. The American Astronomical Society. All rights reserved..
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extreme Orbital Evolution from hierarchical secular coupling of two giant planets
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: Jean Teyssandier, Smadar Naoz, Ian Lizarraga, Frederic A RasioAbstract:Observations of exoplanets over the last two decades have revealed a new class of Jupiter-size planets with Orbital periods of a few days, the so-called "hot Jupiters". Recent measurements using the Rossiter-McLaughlin effect have shown that many (~ 50%) of these planets are misaligned; furthermore, some (~ 15%) are even retrograde with respect to the stellar spin axis. Motivated by these observations, we explore the possibility of forming retrograde orbits in hierarchical triple configurations consisting of a star-planet inner pair with another giant planet, or brown dwarf, in a much wider orbit. Recently Naoz et al. (2011) showed that in such a system, the inner planet's orbit can flip back and forth from prograde to retrograde, and can also reach extremely high eccentricities. Here we map a significant part of the parameter space of dynamical outcomes for these systems. We derive strong constraints on the Orbital configurations for the outer perturber that could lead to the formation of hot Jupiters with misaligned or retrograde orbits. We focus only on the secular Evolution, neglecting other dynamical effects such as mean-motion resonances, as well as all dissipative forces. For example, with an inner Jupiter-like planet initially on a nearly circular orbit at 5 AU, we show that a misaligned hot Jupiter is likely to be formed in the presence of a more massive planetary companion (> 2 MJ) within 140 AU of the inner system, with mutual inclination 50 degrees and eccentricity above 0.25. This is in striking contrast to the test-particle approximation, where an almost perpendicular configuration can still cause large eccentricity excitations, but flips of an inner Jupiter-like planet are much less likely to occur. The constraints we derive can be used to guide future observations, and, in particular, searches for more distant companions in systems containing a hot Jupiter.
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interacting binaries with eccentric orbits iii Orbital Evolution due to direct impact and self accretion
The Astrophysical Journal, 2010Co-Authors: J F Sepinsky, B Willems, V Kalogera, Frederic A RasioAbstract:The rapid circularization and synchronization of the stellar components in an eccentric binary system at the onset of Roche lobe overflow is a fundamental assumption common to all binary stellar Evolution and population synthesis codes, even though the validity of this assumption is questionable both theoretically and observationally. Here we calculate the Evolution of the Orbital elements of an eccentric binary through the direct three-body integration of a massive particle ejected through the inner Lagrangian point of the donor star at periastron. The trajectory of this particle leads to three possible outcomes: direct accretion onto the companion star within a single orbit, self-accretion back onto the donor star within a single orbit, or a quasi-periodic orbit around the companion star, possibly leading to the formation of a disk. We calculate the secular Evolution of the binary orbit in the first two cases and conclude that direct impact accretion can increase as well as decrease the Orbital semimajor axis and eccentricity, while self-accretion always decreases the Orbital semimajor axis and eccentricity. In cases where mass overflow contributes to circularizing the orbit, circularization can set in on timescales as short as a few percent of the mass-transfer timescale. In cases where mass overflow increases the eccentricity, the Orbital Evolution is governed by competition between mass overflow and tidal torques. In the absence of tidal torques, mass overflow results in direct impact can lead to substantially subsynchronously rotating donor stars. Contrary to assumptions common in the literature, direct impact accretion furthermore does not always provide a strong sink of Orbital angular momentum in close mass-transferring binaries; in fact, we instead find that a significant part can be returned to the orbit during the particle orbit. The formulation presented in this paper together with our previous work can be combined with stellar and binary Evolution codes to generate a better picture of the Evolution of eccentric, Roche lobe overflowing binary star systems.
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interacting binaries with eccentric orbits iii Orbital Evolution due to direct impact and self accretion
arXiv: Solar and Stellar Astrophysics, 2010Co-Authors: J F Sepinsky, B Willems, V Kalogera, Frederic A RasioAbstract:The rapid circularization and synchronization of the stellar components in an eccentric binary system at the onset of Roche lobe overflow (RLO) is a fundamental assumption common to all binary stellar Evolution and population synthesis codes, even though the validity of this assumption is questionable both theoretically and observationally. Here we calculate the Evolution of the Orbital elements of an eccentric binary through the direct three-body integration of a massive particle ejected through the inner Lagrangian point of the donor star at periastron. The trajectory of this particle leads to three possible outcomes: direct accretion (DA) onto the companion star within a single orbit, self-accretion (SA) back onto the donor star within a single orbit, or a quasi-periodic orbit around the companion star. We calculate the secular Evolution of the binary orbit in the first two cases and conclude that DA can increase or decrease the Orbital semi-major axis and eccentricity, while SA always decreases the Orbital both Orbital elements. In cases where mass overflow contributes to circularizing the orbit, circularization can set in on timescales as short as a few per cent of the mass transfer timescale. In cases where mass overflow increases the eccentricity, the Orbital Evolution is governed by competition between mass overflow and tidal torques. In the absence of tidal torques, mass overflow resulting in DI can lead to substantially subsynchronously rotating donor stars. Contrary to common assumptions, DI furthermore does not always provide a strong sink of Orbital angular momentum in close mass-transferring binaries; in fact we instead find that a significant part can be returned to the orbit during the particle orbit. The formulation presented here can be combined with stellar and binary Evolution codes to generate a better picture of the Evolution of eccentric, RLO binary star systems.
J F Sepinsky - One of the best experts on this subject based on the ideXlab platform.
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interacting binaries with eccentric orbits iii Orbital Evolution due to direct impact and self accretion
The Astrophysical Journal, 2010Co-Authors: J F Sepinsky, B Willems, V Kalogera, Frederic A RasioAbstract:The rapid circularization and synchronization of the stellar components in an eccentric binary system at the onset of Roche lobe overflow is a fundamental assumption common to all binary stellar Evolution and population synthesis codes, even though the validity of this assumption is questionable both theoretically and observationally. Here we calculate the Evolution of the Orbital elements of an eccentric binary through the direct three-body integration of a massive particle ejected through the inner Lagrangian point of the donor star at periastron. The trajectory of this particle leads to three possible outcomes: direct accretion onto the companion star within a single orbit, self-accretion back onto the donor star within a single orbit, or a quasi-periodic orbit around the companion star, possibly leading to the formation of a disk. We calculate the secular Evolution of the binary orbit in the first two cases and conclude that direct impact accretion can increase as well as decrease the Orbital semimajor axis and eccentricity, while self-accretion always decreases the Orbital semimajor axis and eccentricity. In cases where mass overflow contributes to circularizing the orbit, circularization can set in on timescales as short as a few percent of the mass-transfer timescale. In cases where mass overflow increases the eccentricity, the Orbital Evolution is governed by competition between mass overflow and tidal torques. In the absence of tidal torques, mass overflow results in direct impact can lead to substantially subsynchronously rotating donor stars. Contrary to assumptions common in the literature, direct impact accretion furthermore does not always provide a strong sink of Orbital angular momentum in close mass-transferring binaries; in fact, we instead find that a significant part can be returned to the orbit during the particle orbit. The formulation presented in this paper together with our previous work can be combined with stellar and binary Evolution codes to generate a better picture of the Evolution of eccentric, Roche lobe overflowing binary star systems.
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interacting binaries with eccentric orbits iii Orbital Evolution due to direct impact and self accretion
arXiv: Solar and Stellar Astrophysics, 2010Co-Authors: J F Sepinsky, B Willems, V Kalogera, Frederic A RasioAbstract:The rapid circularization and synchronization of the stellar components in an eccentric binary system at the onset of Roche lobe overflow (RLO) is a fundamental assumption common to all binary stellar Evolution and population synthesis codes, even though the validity of this assumption is questionable both theoretically and observationally. Here we calculate the Evolution of the Orbital elements of an eccentric binary through the direct three-body integration of a massive particle ejected through the inner Lagrangian point of the donor star at periastron. The trajectory of this particle leads to three possible outcomes: direct accretion (DA) onto the companion star within a single orbit, self-accretion (SA) back onto the donor star within a single orbit, or a quasi-periodic orbit around the companion star. We calculate the secular Evolution of the binary orbit in the first two cases and conclude that DA can increase or decrease the Orbital semi-major axis and eccentricity, while SA always decreases the Orbital both Orbital elements. In cases where mass overflow contributes to circularizing the orbit, circularization can set in on timescales as short as a few per cent of the mass transfer timescale. In cases where mass overflow increases the eccentricity, the Orbital Evolution is governed by competition between mass overflow and tidal torques. In the absence of tidal torques, mass overflow resulting in DI can lead to substantially subsynchronously rotating donor stars. Contrary to common assumptions, DI furthermore does not always provide a strong sink of Orbital angular momentum in close mass-transferring binaries; in fact we instead find that a significant part can be returned to the orbit during the particle orbit. The formulation presented here can be combined with stellar and binary Evolution codes to generate a better picture of the Evolution of eccentric, RLO binary star systems.
M I Saladino - One of the best experts on this subject based on the ideXlab platform.
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gone with the wind the impact of wind mass transfer on the Orbital Evolution of agb binary systems
Astronomy and Astrophysics, 2018Co-Authors: M I Saladino, O R Pols, Inti Pelupessy, E Van Der Helm, Portegies S ZwartAbstract:In low-mass binary systems, mass transfer is likely to occur via a slow and dense stellar wind when one of the stars is in the asymptotic giant branch (AGB) phase. Observations show that many binaries that have undergone AGB mass transfer have Orbital periods of 1–10 yr, at odds with the predictions of binary population synthesis models. In this paper we investigate the mass-accretion efficiency and angular-momentum loss via wind mass transfer in AGB binary systems and we use these quantities to predict the Evolution of the orbit. To do so, we perform 3D hydrodynamical simulations of the stellar wind lost by an AGB star in the time-dependent gravitational potential of a binary system, using the AMUSE framework. We approximate the thermal Evolution of the gas by imposing a simple effective cooling balance and we vary the Orbital separation and the velocity of the stellar wind. We find that for wind velocities higher than the relative Orbital velocity of the system the flow is described by the Bondi-Hoyle-Lyttleton approximation and the angular-momentum loss is modest, which leads to an expansion of the orbit. On the other hand, for low wind velocities an accretion disk is formed around the companion and the accretion efficiency as well as the angular-momentum loss are enhanced, implying that the orbit will shrink. We find that the transfer of angular momentum from the binary orbit to the outflowing gas occurs within a few Orbital separations from the centre of mass of the binary. Our results suggest that the Orbital Evolution of AGB binaries can be predicted as a function of the ratio of the terminal wind velocity to the relative Orbital velocity of the system, v ∞ /v orb . Our results can provide insight into the puzzling Orbital periods of post-AGB binaries. The results also suggest that the number of stars entering into the common-envelope phase will increase, which can have significant implications for the expected formation rates of the end products of low-mass binary Evolution, such as cataclysmic binaries, type Ia supernovae, and double white-dwarf mergers.
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gone with the wind the impact of wind mass transfer on the Orbital Evolution of agb binary systems
Astronomy and Astrophysics, 2018Co-Authors: M I Saladino, O R Pols, E Van Der Helm, Inti Pelupessy, S Portegies F ZwartAbstract:In low-mass binary systems, mass transfer is likely to occur via a slow and dense stellar wind when one of the stars is in the AGB phase. Observations show that many binaries that have undergone AGB mass transfer have Orbital periods of 1-10 yr, at odds with the predictions of binary population synthesis models. We investigate the mass-accretion efficiency and angular-momentum loss via wind mass transfer in AGB binary systems. We use these quantities to predict the Evolution of the orbit. We perform 3D hydrodynamical simulations of the stellar wind lost by an AGB star using the AMUSE framework. We approximate the thermal Evolution of the gas by imposing a simple effective cooling balance and we vary the Orbital separation and the velocity of the stellar wind. We find that for wind velocities $v_{\infty}$ larger than the relative Orbital velocity of the system $v_\mathrm{orb}$ the flow is described by the Bondi-Hoyle-Lyttleton approximation and the angular-momentum loss is modest, leading to an expansion of the orbit. For low wind velocities an accretion disk is formed around the companion and the accretion efficiency as well as the angular-momentum loss are enhanced, implying that the orbit will shrink. We find that the transfer of angular momentum from the orbit to the outflowing gas occurs within a few Orbital separations from the center of mass of the binary. Our results suggest that the Orbital Evolution of AGB binaries can be predicted as a function of the ratio $v_{\infty}/v_\mathrm{orb}$. Our results can provide insight into the puzzling Orbital periods of post-AGB binaries and suggest that the number of stars entering into the common-envelope phase will increase. The latter can have significant implications for the expected formation rates of the end products of low-mass binary Evolution, such as cataclysmic binaries, type Ia supernova and double white-dwarf mergers. [ABRIDGED]
Ryan Miranda - One of the best experts on this subject based on the ideXlab platform.
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hydrodynamics of circumbinary accretion angular momentum transfer and binary Orbital Evolution
The Astrophysical Journal, 2019Co-Authors: Diego J Munoz, Ryan MirandaAbstract:We carry out 2D viscous hydrodynamical simulations of circumbinary accretion using the AREPO code. We self-consistently compute the accretion flow over a wide range of spatial scales, from the circumbinary disk (CBD) far from the central binary, through accretion streamers, to the disks around individual binary components, resolving the flow down to 2% of the binary separation. We focus on equal-mass binaries with arbitrary eccentricities. We evolve the flow over long (viscous) timescales until a quasi-steady is reached, in which the mass supply rate at large distances $\dot{M}_0$ (assumed constant) equals the time-averaged mass transfer rate across the disk and the total mass accretion rate onto the binary components. This quasi-steady state allows us to compute the secular angular momentum transfer rate onto the binary, $\langle\dot{J}_b\rangle$, and the resulting Orbital Evolution. Through direct computation of the gravitational and accretion torques on the binary, we find that $\langle\dot{J}_b\rangle$ is consistently positive (i.e., the binary gains angular momentum), with $l_0\equiv\langle\dot{J}_b\rangle/\dot M_0$ in the range of $(0.4-0.8)a_b^2\Omega_b$, depending on the binary eccentricity (where $a_b,~\Omega_b$ are the binary semi-major axis and angular frequency); we also find that this $\langle\dot{J}_b\rangle$ is equal to the net angular momentum current across the CBD, indicating that global angular momentum balance is achieved in our simulations. We compute the time-averaged rate of change of the binary Orbital energy for eccentric binaries, and thus obtain the secular rates $\langle\dot a_b\rangle$ and $\langle \dot{e}_b\rangle$. In all cases, $\langle\dot{a}_b\rangle$ is positive, i.e., the binary expands while accreting. We discuss the implications of our results for the merger of supermassive binary black holes and for the formation of close stellar binaries.
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hydrodynamics of circumbinary accretion angular momentum transfer and binary Orbital Evolution
The Astrophysical Journal, 2019Co-Authors: Diego J Munoz, Ryan Miranda, Dong LaiAbstract:NSF [AST1715246]; NASA [NNX14AP31G]; Office of the Provost; Northwestern University Information Technology
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hydrodynamics of circumbinary accretion angular momentum transfer and binary Orbital Evolution
arXiv: High Energy Astrophysical Phenomena, 2018Co-Authors: Diego J Munoz, Ryan Miranda, Dong LaiAbstract:We carry out 2D viscous hydrodynamical simulations of circumbinary accretion using the AREPO code. We self-consistently compute the accretion flow over a wide range of spatial scales, from the circumbinary disk (CBD) far from the central binary, through accretion streamers, to the disks around individual binary components, resolving the flow down to 2% of the binary separation. We focus on equal-mass binaries with arbitrary eccentricities. We evolve the flow over long (viscous) timescales until a quasi-steady is reached, in which the mass supply rate at large distances $\dot{M}_0$ (assumed constant) equals the time-averaged mass transfer rate across the disk and the total mass accretion rate onto the binary components. This quasi-steady state allows us to compute the secular angular momentum transfer rate onto the binary, $\langle\dot{J}_b\rangle$, and the resulting Orbital Evolution. Through direct computation of the gravitational and accretion torques on the binary, we find that $\langle\dot{J}_b\rangle$ is consistently positive (i.e., the binary gains angular momentum), with $l_0\equiv\langle\dot{J}_b\rangle/\dot M_0$ in the range of $(0.4-0.8)a_b^2\Omega_b$, depending on the binary eccentricity (where $a_b,~\Omega_b$ are the binary semi-major axis and angular frequency); we also find that this $\langle\dot{J}_b\rangle$ is equal to the net angular momentum current across the CBD, indicating that global angular momentum balance is achieved in our simulations. We compute the time-averaged rate of change of the binary Orbital energy for eccentric binaries, and thus obtain the secular rates $\langle\dot a_b\rangle$ and $\langle \dot{e}_b\rangle$. In all cases, $\langle\dot{a}_b\rangle$ is positive, i.e., the binary expands while accreting. We discuss the implications of our results for the merger of supermassive binary black holes and for the formation of close stellar binaries.
Diego J Munoz - One of the best experts on this subject based on the ideXlab platform.
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hydrodynamics of circumbinary accretion angular momentum transfer and binary Orbital Evolution
The Astrophysical Journal, 2019Co-Authors: Diego J Munoz, Ryan MirandaAbstract:We carry out 2D viscous hydrodynamical simulations of circumbinary accretion using the AREPO code. We self-consistently compute the accretion flow over a wide range of spatial scales, from the circumbinary disk (CBD) far from the central binary, through accretion streamers, to the disks around individual binary components, resolving the flow down to 2% of the binary separation. We focus on equal-mass binaries with arbitrary eccentricities. We evolve the flow over long (viscous) timescales until a quasi-steady is reached, in which the mass supply rate at large distances $\dot{M}_0$ (assumed constant) equals the time-averaged mass transfer rate across the disk and the total mass accretion rate onto the binary components. This quasi-steady state allows us to compute the secular angular momentum transfer rate onto the binary, $\langle\dot{J}_b\rangle$, and the resulting Orbital Evolution. Through direct computation of the gravitational and accretion torques on the binary, we find that $\langle\dot{J}_b\rangle$ is consistently positive (i.e., the binary gains angular momentum), with $l_0\equiv\langle\dot{J}_b\rangle/\dot M_0$ in the range of $(0.4-0.8)a_b^2\Omega_b$, depending on the binary eccentricity (where $a_b,~\Omega_b$ are the binary semi-major axis and angular frequency); we also find that this $\langle\dot{J}_b\rangle$ is equal to the net angular momentum current across the CBD, indicating that global angular momentum balance is achieved in our simulations. We compute the time-averaged rate of change of the binary Orbital energy for eccentric binaries, and thus obtain the secular rates $\langle\dot a_b\rangle$ and $\langle \dot{e}_b\rangle$. In all cases, $\langle\dot{a}_b\rangle$ is positive, i.e., the binary expands while accreting. We discuss the implications of our results for the merger of supermassive binary black holes and for the formation of close stellar binaries.
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hydrodynamics of circumbinary accretion angular momentum transfer and binary Orbital Evolution
The Astrophysical Journal, 2019Co-Authors: Diego J Munoz, Ryan Miranda, Dong LaiAbstract:NSF [AST1715246]; NASA [NNX14AP31G]; Office of the Provost; Northwestern University Information Technology
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hydrodynamics of circumbinary accretion angular momentum transfer and binary Orbital Evolution
arXiv: High Energy Astrophysical Phenomena, 2018Co-Authors: Diego J Munoz, Ryan Miranda, Dong LaiAbstract:We carry out 2D viscous hydrodynamical simulations of circumbinary accretion using the AREPO code. We self-consistently compute the accretion flow over a wide range of spatial scales, from the circumbinary disk (CBD) far from the central binary, through accretion streamers, to the disks around individual binary components, resolving the flow down to 2% of the binary separation. We focus on equal-mass binaries with arbitrary eccentricities. We evolve the flow over long (viscous) timescales until a quasi-steady is reached, in which the mass supply rate at large distances $\dot{M}_0$ (assumed constant) equals the time-averaged mass transfer rate across the disk and the total mass accretion rate onto the binary components. This quasi-steady state allows us to compute the secular angular momentum transfer rate onto the binary, $\langle\dot{J}_b\rangle$, and the resulting Orbital Evolution. Through direct computation of the gravitational and accretion torques on the binary, we find that $\langle\dot{J}_b\rangle$ is consistently positive (i.e., the binary gains angular momentum), with $l_0\equiv\langle\dot{J}_b\rangle/\dot M_0$ in the range of $(0.4-0.8)a_b^2\Omega_b$, depending on the binary eccentricity (where $a_b,~\Omega_b$ are the binary semi-major axis and angular frequency); we also find that this $\langle\dot{J}_b\rangle$ is equal to the net angular momentum current across the CBD, indicating that global angular momentum balance is achieved in our simulations. We compute the time-averaged rate of change of the binary Orbital energy for eccentric binaries, and thus obtain the secular rates $\langle\dot a_b\rangle$ and $\langle \dot{e}_b\rangle$. In all cases, $\langle\dot{a}_b\rangle$ is positive, i.e., the binary expands while accreting. We discuss the implications of our results for the merger of supermassive binary black holes and for the formation of close stellar binaries.
