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Sean N Raymond - One of the best experts on this subject based on the ideXlab platform.
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formation of Planetary Systems by pebble accretion and migration growth of gas giants
Astronomy and Astrophysics, 2019Co-Authors: Bertram Bitsch, Andre Izidoro, Anders Johansen, Sean N Raymond, Alessandro Morbidelli, Michiel Lambrechts, Seth A JacobsonAbstract:Giant planets migrate though the protoPlanetary disc as they grow their solid core and attract their gaseous envelope. Previously, we have studied the growth and migration of an isolated planet in an evolving disc. Here, we generalise such models to include the mutual gravitational interaction between a high number of growing Planetary bodies. We have investigated how the formation of Planetary Systems depends on the radial flux of pebbles through the protoPlanetary disc and on the planet migration rate. Our N-body simulations confirm previous findings that Jupiter-like planets in orbits outside the water ice line originate from embryos starting out at 20-40 AU when using nominal type-I and type-II migration rates and a pebble flux of approximately 100-200 Earth masses per million years, enough to grow Jupiter within the lifetime of the solar nebula. The Planetary embryos placed up to 30 AU migrate into the inner system (r P < 1AU). There they form super-Earths or hot and warm gas giants, producing Systems that are inconsistent with the configuration of the solar system, but consistent with some exoPlanetary Systems. We also explored slower migration rates which allow the formation of gas giants from embryos originating from the 5-10 AU region, which are stranded exterior to 1 AU at the end of the gas-disc phase. These giant planets can also form in discs with lower pebbles fluxes (50-100 Earth masses per Myr). We identify a pebble flux threshold below which migration dominates and moves the Planetary core to the inner disc, where the pebble isolation mass is too low for the planet to accrete gas efficiently. In our model, giant planet growth requires a sufficiently high pebble flux to enable growth to out-compete migration. An even higher pebble flux produces Systems with multiple gas giants. We show that Planetary embryos starting interior to 5 AU do not grow into gas giants, even if migration is slow and the pebble flux is large. These embryos instead grow to just a few Earth masses, the mass regime of super-Earths. This stunted growth is caused by the low pebble isolation mass in the inner disc and is therefore independent of the pebble flux. Additionally, we show that the long-term evolution of our formed Planetary Systems can naturally produce Systems with inner super-Earths and outer gas giants as well as Systems of giant planets on very eccentric orbits.
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formation of Planetary Systems by pebble accretion and migration growth of gas giants
arXiv: Earth and Planetary Astrophysics, 2019Co-Authors: Bertram Bitsch, Andre Izidoro, Anders Johansen, Sean N Raymond, Alessandro Morbidelli, Michiel Lambrechts, Seth A JacobsonAbstract:Giant planets migrate though the protoPlanetary disc as they grow. We investigate how the formation of Planetary Systems depends on the radial flux of pebbles through the protoPlanetary disc and on the planet migration rate. Our N-body simulations confirm previous findings that Jupiter-like planets in orbits outside the water ice line originate from embryos starting out at 20-40 AU when using nominal type-I and type-II migration rates and a pebble flux of 100-200 Earth masses per million years, enough to grow Jupiter within the lifetime of the solar nebula. The Planetary embryos placed up to 30AU migrate into the inner system (r<1AU) and form super-Earths or hot and warm gas giants, producing Systems that are inconsistent with the configuration of the solar system, but consistent with some exoPlanetary Systems. We also explore slower migration rates which allow the formation of gas giants from embryos originating from the 5-10AU region, which are stranded exterior to 1 AU at the end of the gas-disc phase. We identify a pebble flux threshold below which migration dominates and moves the Planetary core to the inner disc, where the pebble isolation mass is too low for the planet to accrete gas efficiently. Giant planet growth requires a sufficiently-high pebble flux to enable growth to out-compete migration. Even higher pebble fluxes produce Systems with multiple gas giants. We show that Planetary embryos starting interior to 5AU do not grow into gas giants, even if migration is slow and the pebble flux is large. Instead they grow to the mass regime of super-Earths. This stunted growth is caused by the low pebble isolation mass in the inner disc and is independent of the pebble flux. Additionally we show that the long term evolution of our formed Planetary Systems can produce Systems with hot super-Earths and outer gas giants as well as Systems of giants on eccentric orbits (abridged).
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The Long-Term Dynamical Evolution of Planetary Systems
2013Co-Authors: Melvyn B. Davies, Sean N Raymond, Alessandro Morbidelli, Fred C. Adams, Philip Armitage, John Chambers, Eric Ford, Dimitri VerasAbstract:This chapter concerns the long-term dynamical evolution of Planetary Systems from both theoretical and observational perspectives. We begin by discussing the planet-planet interactions that take place within our own Solar System. We then describe such interactions in more tightly-packed Planetary Systems. As planet-planet interactions build up, some Systems become dynamically unstable, leading to strong encounters and ultimately either ejections or collisions of planets. After discussing the basic physical processes involved, we consider how these interactions apply to extrasolar Planetary Systems and explore the constraints provided by observed Systems. The presence of a residual planetesimal disc can lead to Planetary migration and hence cause instabilities induced by resonance crossing; however, such discs can also stabilise Planetary Systems. The crowded birth environment of a Planetary system can have a significant impact: close encounters and binary companions can act to destabilise Systems, or sculpt their properties. In the case of binaries, the Kozai mechanism can place planets on extremely eccentric orbits which may later circularise to produce hot Jupiters.
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planet planet scattering in planetesimal disks ii predictions for outer extrasolar Planetary Systems
The Astrophysical Journal, 2010Co-Authors: Sean N Raymond, Philip J. Armitage, Noel GorelickAbstract:We develop an idealized dynamical model to predict the typical properties of outer extrasolar Planetary Systems, at radii comparable to the Jupiter-to-Neptune region of the solar system. The model is based upon the hypothesis that dynamical evolution in outer Planetary Systems is controlled by a combination of planet-planet scattering and Planetary interactions with an exterior disk of small bodies ('planetesimals'). Our results are based on 5000 long duration N-body simulations that follow the evolution of three planets from a few to 10 AU, together with a planetesimal disk containing 50 M{sub +} from 10 to 20 AU. For large planet masses (M {approx}> M{sub Sat}), the model recovers the observed eccentricity distribution of extrasolar planets. For lower-mass planets, the range of outcomes in models with disks is far greater than that which is seen in isolated planet-planet scattering. Common outcomes include strong scattering among massive planets, sudden jumps in eccentricity due to resonance crossings driven by divergent migration, and re-circularization of scattered low-mass planets in the outer disk. We present the distributions of the eccentricity and inclination that result, and discuss how they vary with planet mass and initial system architecture. In agreement with other studies, we find that themore » currently observed eccentricity distribution (derived primarily from planets at a {approx}< 3 AU) is consistent with isolated planet-planet scattering. We explain the observed mass dependence-which is in the opposite sense from that predicted by the simplest scattering models-as a consequence of strong correlations between planet masses in the same system. At somewhat larger radii, initial Planetary mass correlations and disk effects can yield similar modest changes to the eccentricity distribution. Nonetheless, strong damping of eccentricity for low-mass planets at large radii appears to be a secure signature of the dynamical influence of disks. Radial velocity measurements capable of detecting planets with K {approx} 5 m s{sup -1} and periods in excess of 10 years will provide constraints on this regime. Finally, we present an analysis of the predicted separation of planets in two-planet Systems, and of the population of planets in mean-motion resonances (MMRs). We show that, if there are Systems with {approx} Jupiter-mass planets that avoid close encounters, the planetesimal disk acts as a damping mechanism and populates MMRs at a very high rate (50%-80%). In many cases, resonant chains (in particular the 4:2:1 Laplace resonance) are set up among all three planets. We expect such resonant chains to be common among massive planets in outer Planetary Systems.« less
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Planet-planet scattering in planetesimal disks II: Predictions for outer extrasolar Planetary Systems
The Astrophysical Journal, 2010Co-Authors: Sean N Raymond, Philip J. Armitage, Noel GorelickAbstract:We develop an idealized dynamical model to predict the typical properties of outer extrasolar Planetary Systems, at radii beyond 5 AU. Our hypothesis is that dynamical evolution in outer Planetary Systems is controlled by a combination of planet-planet scattering and Planetary interactions with an exterior disk of small bodies ("planetesimals"). Using 5,000 long duration N-body simulations, we follow the evolution of three planets surrounded by a 50 Earth mass primordial planetesimal disk. For large planet masses (above that of Saturn) the influence of the disk is modest, and we recover the observed eccentricity distribution of extrasolar planets (observed primarily at smaller radii). We explain the observed mass dependence of the eccentricity by invoking strong correlations between planet masses in the same system. For lower mass planets we observe diverse dynamical behavior: strong scattering events, sudden jumps in eccentricity due to resonance crossings, and re-circularization of scattered low-mass planets in the disk. We present distributions of the final eccentricity and inclination, and discuss how they vary with planet mass and initial system architecture. We predict a transition to lower eccentricities for low mass planets at radii where disks influence the dynamics. Radial velocity measurements capable of detecting planets with K~5 m/s and periods in excess of 10 years will constrain this regime. We also study the population of resonant and non-resonant multiple planet Systems. We show that, among Systems with Jupiter-mass planets that avoid close encounters, the planetesimal disk acts as a damping mechanism that frequently populates mean motion resonances. Resonant chains ought to be common among massive planets in outer Planetary Systems.
Frederic A Rasio - One of the best experts on this subject based on the ideXlab platform.
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probing the survival of Planetary Systems in globular clusters with tidal disruption events
The Astrophysical Journal, 2019Co-Authors: Kyle Kremer, S Chatterjee, Daniel J Dorazio, Johan Samsing, Frederic A RasioAbstract:Among the growing list of confirmed exoplanets, the number of planets identified in dense star clusters remains sparse. Previous analyses have suggested this may be due in part to dynamical interactions that unbind large fractions of planets from their host stars, limiting the survival of Planetary Systems in clusters. Thus, alternative detection strategies may be necessary to study planets in clusters that may no longer be bound to a host star. Here, we use the cluster Monte Carlo code CMC to explore the evolution of Planetary Systems in dense star clusters. Depending on a number of initial conditions, we show that $10-50\%$ of primordial Planetary Systems are broken through dynamical encounters over a cluster's full lifetime, populating clusters with "free-floating" planets. Furthermore, a large number ($30-80\%$) of planets are ejected from their host cluster through strong dynamical encounters and/or tidal loss. Additionally, we show that planets naturally mix with stellar-mass black holes (BHs) in the central regions of their host cluster. As a consequence, up to a few hundreds of planets will be tidally disrupted through close passages of BHs. We show these BH-planet tidal disruption events (TDEs) occur in clusters at a rate of up to $10^{-5}\,\rm{yr}^{-1}$ in a Milky Way-type galaxy. We predict BH-planet TDEs should be detected by upcoming transient surveys such as LSST at a rate of roughly a few events per year. The observed rate of BH-planet TDEs would place new constraints upon the formation and survival of both Planetary Systems and BHs in dense star clusters. Additionally, depending on various assumptions including the initial number of planets and their orbital properties, we predict that typical globular clusters may contain a few dynamically-formed NS-planet Systems at present as well as up to roughly 100 dynamically-formed WD-planet Systems.
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unstable Planetary Systems emerging out of gas disks
The Astrophysical Journal, 2010Co-Authors: Soko Matsumura, Edward W Thommes, S Chatterjee, Frederic A RasioAbstract:The discovery of over 400 extrasolar planets allows us to statistically test our understanding of the formation and dynamics of Planetary Systems via numerical simulations. Traditional N-body simulations of multiple-planet Systems without gas disks have successfully reproduced the eccentricity (e) distribution of the observed Systems by assuming that the Planetary Systems are relatively closely packed when the gas disk dissipates, so that they become dynamically unstable within the stellar lifetime. However, such studies cannot explain the small semimajor axes a of extrasolar Planetary Systems, if planets are formed, as the standard planet formation theory suggests, beyond the ice line. In this paper, we numerically study the evolution of three-planet Systems in dissipating gas disks, and constrain the initial conditions that reproduce the observed a and e distributions simultaneously. We adopt initial conditions that are motivated by the standard planet formation theory, and self-consistently simulate the disk evolution and planet migration, by using a hybrid N-body and one-dimensional gas disk code. We also take into account eccentricity damping, and investigate the effect of saturation of corotation resonances on the evolution of Planetary Systems. We find that the a distribution is largely determined in a gas disk, while the e distribution is determined after the disk dissipation. We also find that there may be an optimum disk mass which leads to the observed a-e distribution. Our simulations generate a larger fraction of Planetary Systems trapped in mean-motion resonances (MMRs) than the observations, indicating that the disk's perturbation to the Planetary orbits may be important to explain the observed rate of MMRs. We also find a much lower occurrence of planets on retrograde orbits than the current observations of close-in planets suggest.
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gas disks to gas giants simulating the birth of Planetary Systems
EXOPLANETS AND DISKS: THEIR FORMATION AND DIVERSITY: Proceedings of the International Conference, 2009Co-Authors: Soko Matsumura, Edward W Thommes, Frederic A RasioAbstract:The ensemble of now well over 300 discovered Planetary Systems displays a wide range of masses, orbits and—in multiple Systems—dynamical interactions. These represent the endpoint of a complex sequence of events, wherein an entire protostellar disk converts itself into a small number of Planetary bodies. Here we present self‐consistent numerical simulations of this process, which produce results in agreement with some of the key trends observed in the properties of the exoplanets. Though the typical formation history of a Planetary system is highly stochastic, there are nevertheless clear correlations between a system’s birth disk and the characteristics of the mature Planetary system which ultimately grows from it. Analogues to our own Solar System appear to be a less common outcome, originating from disks near the boundary between barren and (giant) planet‐forming.
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unstable Planetary Systems emerging out of gas disks
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: Soko Matsumura, Edward W Thommes, S Chatterjee, Frederic A RasioAbstract:The discovery of over 400 extrasolar planets allows us to statistically test our understanding of formation and dynamics of Planetary Systems via numerical simulations. Traditional N-body simulations of multiple-planet Systems without gas disks have successfully reproduced the eccentricity (e) distribution of the observed Systems, by assuming that the Planetary Systems are relatively closely packed when the gas disk dissipates, so that they become dynamically unstable within the stellar lifetime. However, such studies cannot explain the small semi-major axes (a) of extrasolar Planetary Systems, if planets are formed, as the standard planet formation theory suggests, beyond the ice line. In this paper, we numerically study the evolution of three-planet Systems in dissipating gas disks, and constrain the initial conditions that reproduce the observed semi-major axis and eccentricity distributions simultaneously. We adopt the initial conditions that are motivated by the standard planet formation theory, and self-consistently simulate the disk evolution, and planet migration by using a hybrid N-body and 1D gas disk code. We also take account of eccentricity damping, and investigate the effect of saturation of corotation resonances on the evolution of Planetary Systems. We find that the semi-major axis distribution is largely determined in a gas disk, while the eccentricity distribution is determined after the disk dissipation. We also find that there may be an optimum disk mass which leads to the observed a-e distribution. Our simulations generate a larger fraction of Planetary Systems trapped in mean-motion resonances (MMRs) than the observations, indicating that the disk's perturbation to the Planetary orbits may be important to explain the observed rate of MMRs. We also find much lower occurrence of planets on retrograde orbits than the current observations of close-in planets suggest.
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gas disks to gas giants simulating the birth of Planetary Systems
DPS, 2009Co-Authors: Soko Matsumura, Edward W Thommes, Frederic A RasioAbstract:The ensemble of now more than 250 discovered Planetary Systems displays a wide range of masses, orbits and, in multiple Systems, dynamical interactions. These represent the end point of a complex sequence of events, wherein an entire protostellar disk converts itself into a small number of Planetary bodies. Here, we present self-consistent numerical simulations of this process, which produce results in agreement with some of the key trends observed in the properties of the exoplanets. Analogs to our own solar system do not appear to be common, originating from disks near the boundary between barren and (giant) planet-forming.
Adrian Brunini - One of the best experts on this subject based on the ideXlab platform.
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core instability models of giant planet accretion ii forming Planetary Systems
Monthly Notices of the Royal Astronomical Society, 2009Co-Authors: Yamila Miguel, Adrian BruniniAbstract:We develop a simple model for computing Planetary formation based on the core instability model for the gas accretion and the oligarchic growth regime for the accretion of the solid core. In this model several planets can form simultaneously in the disc, a fact that has important implications especially for the changes in the dynamic of the planetesimals and the growth of the cores since we consider the collision between them as a source of potential growth. The type I and type II migration of the embryos and the migration of the planetesimals due to the interaction with the disc of gas are also taken into account. With this model we consider different initial conditions to generate a variety of Planetary Systems and analyse them statistically. We explore the effects of using different type I migration rates on the final number of planets formed per Planetary system such as on the distribution of masses and semimajor axis of extrasolar planets, where we also analyse the implications of considering different gas accretion rates. A particularly interesting result is the generation of a larger population of habitable planets when the gas accretion rate and type I migration are slower.
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core instability models of giant planet accretion ii forming Planetary Systems
arXiv: Astrophysics, 2008Co-Authors: Yamila Miguel, Adrian BruniniAbstract:We develop a simple model for computing Planetary formation based on the core instability model for the gas accretion and the oligarchic growth regime for the accretion of the solid core. In this model several planets can form simultaneously in the disc, a fact that has important implications specially for the changes in the dynamic of the planetesimals and the growth of the cores since we consider the collision between them as a source of potential growth. The type I and II migration of the embryos and the migration of the planetesimals due to the interaction with the disc of gas are also taken into account. With this model we consider different initial conditions to generate a variety of Planetary Systems and analyse them statistically. We explore the effects of using different type I migration rates on the final number of planets formed per Planetary system such as on the distribution of masses and semimajor axis of extrasolar planets, where we also analyse the implications of considering different gas accretion rates. A particularly interesting result is the generation of a larger population of habitable planets when the gas accretion rate and type I migration are slower.
Jeanluc Margot - One of the best experts on this subject based on the ideXlab platform.
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are Planetary Systems filled to capacity a study based on kepler results
The Astrophysical Journal, 2013Co-Authors: Julia Fang, Jeanluc MargotAbstract:We used a sample of Kepler candidate planets with orbital periods less than 200 days and radii between 1.5 and 30 Earth radii (R ⊕) to determine the typical dynamical spacing of neighboring planets. To derive the intrinsic (i.e., free of observational bias) dynamical spacing of neighboring planets, we generated populations of Planetary Systems following various dynamical spacing distributions, subjected them to synthetic observations by the Kepler spacecraft, and compared the properties of observed planets in our simulations with actual Kepler detections. We found that, on average, neighboring planets are spaced 21.7 mutual Hill radii apart with a standard deviation of 9.5. This dynamical spacing distribution is consistent with that of adjacent planets in the solar system. To test the packed Planetary Systems hypothesis, the idea that all Planetary Systems are dynamically packed or filled to capacity, we determined the fraction of Systems that are dynamically packed by performing long-term (108 years) numerical simulations. In each simulation, we integrated a system with planets spaced according to our best-fit dynamical spacing distribution but containing an additional planet on an intermediate orbit. The fraction of simulations exhibiting signs of instability provides an approximate lower bound on the fraction of Systems that are dynamically packed; we found that ≥31%, ≥35%, and ≥45% of two-planet, three-planet, and four-planet Systems are dynamically packed, respectively. Such sizeable fractions suggest that many Planetary Systems are indeed filled to capacity. This feature of Planetary Systems is another profound constraint that formation and evolution models must satisfy.
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are Planetary Systems filled to capacity a study based on kepler results
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: Julia Fang, Jeanluc MargotAbstract:We used a sample of Kepler candidate planets with orbital periods less than 200 days and radii between 1.5 and 30 Earth radii to determine the typical dynamical spacing of neighboring planets. To derive the intrinsic (i.e., free of observational bias) dynamical spacing of neighboring planets, we generated populations of Planetary Systems following various dynamical spacing distributions, subjected them to synthetic observations by the Kepler spacecraft, and compared the properties of observed planets in our simulations with actual Kepler detections. We found that, on average, neighboring planets are spaced 21.7 mutual Hill radii apart with a standard deviation of 9.5. This dynamical spacing distribution is consistent with that of adjacent planets in the Solar System. To test the packed Planetary Systems hypothesis, the idea that all Planetary Systems are dynamically packed or filled to capacity, we determined the fraction of Systems that are dynamically packed by performing long-term (10^8 years) numerical simulations. In each simulation, we integrated a system with planets spaced according to our best-fit dynamical spacing distribution but containing an additional planet on an intermediate orbit. The fraction of simulations exhibiting signs of instability provides an approximate lower bound on the fraction of Systems that are dynamically packed; we found that >31%, >35%, and >45% of 2-planet, 3-planet, and 4-planet Systems are dynamically packed, respectively. Such sizeable fractions suggest that many Planetary Systems are indeed filled to capacity. This feature of Planetary Systems is another profound constraint that formation and evolution models must satisfy.
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architecture of Planetary Systems based on kepler data number of planets and coplanarity
The Astrophysical Journal, 2012Co-Authors: Julia Fang, Jeanluc MargotAbstract:We investigated the underlying architecture of Planetary s ystems by deriving the distribution of planet multiplicity (number of planets) and the distribution of orbital inclinations based on the sample of planet candidates discovered by the Kepler mission. The scope of our study included solar-like stars an d planets with orbital periods less than 200 days and with radii between 1.5 and 30 Earth radii, and was based on Kepler planet candidates detected during Quarters 1 through 6. We created models of Planetary Systems with different distributions of planet multiplicity and inclinations, simulated observat ions of these Systems by Kepler, and compared the properties of the transits of detectable objects to actual Kepler planet detections. Specifically, we compared with both the Kepler sample’s transit numbers and normalized transit duration r atios in order to determine each model’s goodness-of-fit. We did not include any constra ints from radial velocity surveys. Based on our best-fit models, 75-80% of Planetary Systems have 1 or 2 plane ts with orbital periods less than 200 days. In addition, over 85% of planets have orbital inclinations les s than 3 degrees (relative to a common reference plane). This high degree of coplanarity is comparable to tha t seen in our Solar System. These results have implications for planet formation and evolution theories. Low inclinations are consistent with planets forming in a protoPlanetary disk, without significant and lasting pe rturbations from other bodies capable of increasing inclinations. Subject headings:methods: statistical ‐ Planetary Systems ‐ planets and sate llites: general ‐ planets and satellites: detection
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architecture of Planetary Systems based on kepler data number of planets and coplanarity
arXiv: Earth and Planetary Astrophysics, 2012Co-Authors: Julia Fang, Jeanluc MargotAbstract:We investigated the underlying architecture of Planetary Systems by deriving the distribution of planet multiplicity (number of planets) and the distribution of orbital inclinations based on the sample of planet candidates discovered by the Kepler mission. The scope of our study included solar-like stars and planets with orbital periods less than 200 days and with radii between 1.5 and 30 Earth radii, and was based on Kepler planet candidates detected during Quarters 1 through 6. We created models of Planetary Systems with different distributions of planet multiplicity and inclinations, simulated observations of these Systems by Kepler, and compared the properties of the transits of detectable objects to actual Kepler planet detections. Specifically, we compared with both the Kepler sample's transit numbers and normalized transit duration ratios in order to determine each model's goodness-of-fit. We did not include any constraints from radial velocity surveys. Based on our best-fit models, 75-80% of Planetary Systems have 1 or 2 planets with orbital periods less than 200 days. In addition, over 85% of planets have orbital inclinations less than 3 degrees (relative to a common reference plane). This high degree of coplanarity is comparable to that seen in our Solar System. These results have implications for planet formation and evolution theories. Low inclinations are consistent with planets forming in a protoPlanetary disk, followed by evolution without significant and lasting perturbations from other bodies capable of increasing inclinations.
Noel Gorelick - One of the best experts on this subject based on the ideXlab platform.
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planet planet scattering in planetesimal disks ii predictions for outer extrasolar Planetary Systems
The Astrophysical Journal, 2010Co-Authors: Sean N Raymond, Philip J. Armitage, Noel GorelickAbstract:We develop an idealized dynamical model to predict the typical properties of outer extrasolar Planetary Systems, at radii comparable to the Jupiter-to-Neptune region of the solar system. The model is based upon the hypothesis that dynamical evolution in outer Planetary Systems is controlled by a combination of planet-planet scattering and Planetary interactions with an exterior disk of small bodies ('planetesimals'). Our results are based on 5000 long duration N-body simulations that follow the evolution of three planets from a few to 10 AU, together with a planetesimal disk containing 50 M{sub +} from 10 to 20 AU. For large planet masses (M {approx}> M{sub Sat}), the model recovers the observed eccentricity distribution of extrasolar planets. For lower-mass planets, the range of outcomes in models with disks is far greater than that which is seen in isolated planet-planet scattering. Common outcomes include strong scattering among massive planets, sudden jumps in eccentricity due to resonance crossings driven by divergent migration, and re-circularization of scattered low-mass planets in the outer disk. We present the distributions of the eccentricity and inclination that result, and discuss how they vary with planet mass and initial system architecture. In agreement with other studies, we find that themore » currently observed eccentricity distribution (derived primarily from planets at a {approx}< 3 AU) is consistent with isolated planet-planet scattering. We explain the observed mass dependence-which is in the opposite sense from that predicted by the simplest scattering models-as a consequence of strong correlations between planet masses in the same system. At somewhat larger radii, initial Planetary mass correlations and disk effects can yield similar modest changes to the eccentricity distribution. Nonetheless, strong damping of eccentricity for low-mass planets at large radii appears to be a secure signature of the dynamical influence of disks. Radial velocity measurements capable of detecting planets with K {approx} 5 m s{sup -1} and periods in excess of 10 years will provide constraints on this regime. Finally, we present an analysis of the predicted separation of planets in two-planet Systems, and of the population of planets in mean-motion resonances (MMRs). We show that, if there are Systems with {approx} Jupiter-mass planets that avoid close encounters, the planetesimal disk acts as a damping mechanism and populates MMRs at a very high rate (50%-80%). In many cases, resonant chains (in particular the 4:2:1 Laplace resonance) are set up among all three planets. We expect such resonant chains to be common among massive planets in outer Planetary Systems.« less
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Planet-planet scattering in planetesimal disks II: Predictions for outer extrasolar Planetary Systems
The Astrophysical Journal, 2010Co-Authors: Sean N Raymond, Philip J. Armitage, Noel GorelickAbstract:We develop an idealized dynamical model to predict the typical properties of outer extrasolar Planetary Systems, at radii beyond 5 AU. Our hypothesis is that dynamical evolution in outer Planetary Systems is controlled by a combination of planet-planet scattering and Planetary interactions with an exterior disk of small bodies ("planetesimals"). Using 5,000 long duration N-body simulations, we follow the evolution of three planets surrounded by a 50 Earth mass primordial planetesimal disk. For large planet masses (above that of Saturn) the influence of the disk is modest, and we recover the observed eccentricity distribution of extrasolar planets (observed primarily at smaller radii). We explain the observed mass dependence of the eccentricity by invoking strong correlations between planet masses in the same system. For lower mass planets we observe diverse dynamical behavior: strong scattering events, sudden jumps in eccentricity due to resonance crossings, and re-circularization of scattered low-mass planets in the disk. We present distributions of the final eccentricity and inclination, and discuss how they vary with planet mass and initial system architecture. We predict a transition to lower eccentricities for low mass planets at radii where disks influence the dynamics. Radial velocity measurements capable of detecting planets with K~5 m/s and periods in excess of 10 years will constrain this regime. We also study the population of resonant and non-resonant multiple planet Systems. We show that, among Systems with Jupiter-mass planets that avoid close encounters, the planetesimal disk acts as a damping mechanism that frequently populates mean motion resonances. Resonant chains ought to be common among massive planets in outer Planetary Systems.
