The Long-Term Dynamical Evolution of Planetary Systems

Davies, Melvyn B.; Adams, Fred C.; Armitage, Philip J.; Chambers, John E.; Morbidelli, Alessandro; Raymond, Sean N.; Veras, Dimitri

doi:10.2458/azu_uapress_9780816531240-ch034

Cited by 69 publications

(44 citation statements)

References 141 publications

(243 reference statements)

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“…His results imply that planet formation is likely inhibited between 1.75 AU and 4 AU around Kepler-16 meaning that its planet either has migrated (e.g. Goldreich & Tremaine 1979, 1980Lin et al 1996;Ward 1997;Rasio & Ford 1996;Baruteau et al 2014;Davies et al 2014) or has formed in situ. In situ formation would probably reproduce fairly well the pileup that we observe however, gas giant formation inside the snow line requires specific conditions (Bodenheimer et al 2000) and is not expected to take place in circumbinary discs (Paardekooper et al 2012).…”

Section: Bate 2012mentioning

confidence: 99%

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Planets transiting non-eclipsing binaries

Martin

Triaud

2014

A&A

106

141

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The majority of binary stars do not eclipse. Current searches for transiting circumbinary planets concentrate on eclipsing binaries, and are therefore restricted to a small fraction of potential hosts. We investigate the concept of finding planets transiting non-eclipsing binaries, whose geometry would require mutually inclined planes. Using an N-body code we explore how the number and sequence of transits vary as functions of observing time and orbital parameters. The concept is then generalised thanks to a suite of simulated circumbinary systems. Binaries are constructed from radial-velocity surveys of the solar neighbourhood. They are then populated with orbiting gas giants, drawn from a range of distributions. The binary population is shown to be compatible with the Kepler eclipsing binary catalogue, indicating that the properties of binaries may be as universal as the initial mass function. These synthetic systems produce transiting circumbinary planets occurring on both eclipsing and non-eclipsing binaries. Simulated planets transiting eclipsing binaries are compared with published Kepler detections. We find 1) that planets transiting non-eclipsing binaries are probably present in the Kepler data; 2) that observational biases alone cannot account for the observed over-density of circumbinary planets near the stability limit, which implies a physical pile-up; and 3) that the distributions of gas giants orbiting single and binary stars are likely different. Estimating the frequency of circumbinary planets is degenerate with the spread in mutual inclination. Only a minimum occurrence rate can be produced, which we find to be compatible with 9%. Searching for inclined circumbinary planets may significantly increase the population of known objects and will test our conclusions. Their presence, or absence, will reveal the true occurrence rate and help develop circumbinary planet formation theories.

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Section: Bate 2012mentioning

confidence: 99%

“…It would be interesting to know if planet formation -and the planets' subsequent orbital evolution (e.g. Lin et al 1996;Rasio & Ford 1996;Baruteau et al 2014;Davies et al 2014) -happens in a similar manner around single stars and multiple stars. Any difference might offer crucial clues about which formation and evolution scenarios are dominant.…”

mentioning

confidence: 99%

Planets transiting non-eclipsing binaries

Martin

Triaud

2014

A&A

106

141

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“…The eccentricity enables planets on more widely separated orbits to look like HR 8799 during parts of the orbits. A wider separation between the orbits in a system can make the system survive longer than the estimated age of HR 8799 as the stability timescale is strongly dependent on orbital separation (Davies et al 2014).…”

Section: A Stable Solution Without Resonant Lockmentioning

confidence: 99%

“…The timescale of phase A is what we referred to as the stability timescale, which is the time it takes before the first close encounter occurs. This timescale is strongly dependent on orbital separation (Davies et al 2014). The timescale of phase B is independent of initial orbit separation and we measure it to vary between 10 4 to 10 7 years, peaking at 10 6 years.…”

Section: Evolutionary Phasesmentioning

confidence: 99%

Long-term stability of the HR 8799 planetary system without resonant lock

Götberg

Davies

Mustill

et al. 2016

A&A

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HR 8799 is a star accompanied by four massive planets on wide orbits. The observed planetary configuration has been shown to be unstable on a timescale much shorter than the estimated age of the system (∼30 Myr) unless the planets are locked into mean motion resonances. This condition is characterised by small-amplitude libration of one or more resonant angles that stabilise the system by preventing close encounters. We simulate planetary systems similar to the HR 8799 planetary system, exploring the parameter space in separation between the orbits, planetary masses and distance from the Sun to the star. We find systems that look like HR 8799 and remain stable for longer than the estimated age of HR 8799. None of our systems are forced into resonances. We find, with nominal masses (M b = 5 M Jup and M c,d,e = 7 M Jup ) and in a narrow range of orbit separations, that 5 of 100 systems match the observations and lifetime. Considering a broad range of orbit separations, we find 12 of 900 similar systems. The systems survive significantly longer because of their slightly increased initial orbit separations compared to assuming circular orbits from the observed positions. A small increase in separation leads to a significant increase in survival time. The low eccentricity the orbits develop from gravitational interaction is enough for the planets to match the observations. With lower masses, but still comfortably within the estimated planet mass uncertainty, we find 18 of 100 matching and long-lived systems in a narrow orbital separation range. In the broad separation range, we find 82 of 900 matching systems. Our results imply that the planets in the HR 8799 system do not have to be in strong mean motion resonances. We also investigate the future of wide-orbit planetary systems using our HR 8799 analogues. We find that 80% of the systems have two planets left after strong planet-planet scattering and these are on eccentric orbits with semi-major axes of a 1 ∼ 10 AU and a 2 ∼ 30−1000 AU. We speculate that other wide-orbit planetary systems, such as AB Pic and HD 106906, are the remnants of HR 8799 analogues that underwent close encounters and dynamical instability.

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“…All of these mechanisms theoretically can produce gas giants between 1 and 10 Jupiter masses, making it difficult to disentangle the origins of individual planetary systems. Observational tests of these models are further complicated by high extinction at young ages as well as orbital evolution through disk migration, dynamical scattering from other planets or stars, and secular effects like Kozai-Lidov oscillations, all of which gradually erode the fragile fossilized signatures of planet formation (Davies et al 2014).…”

Section: Introductionmentioning

confidence: 99%

NEAR-INFRARED SPECTROSCOPY OF 2M0441+2301 AabBab: A QUADRUPLE SYSTEM SPANNING THE STELLAR TO PLANETARY MASS REGIMES

Bowler

Hillenbrand

2015

ApJ

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We present Keck/NIRC2 and OSIRIS near-infrared imaging and spectroscopy of 2M0441+2301 AabBab, a young (1-3 Myr) hierarchical quadruple system comprising a low-mass star, two brown dwarfs, and a planetarymass companion in Taurus. All four components show spectroscopic signs of low surface gravity, and both 2M0441+2301 Aa and Ab possess Paβ emission indicating they each harbor accretion subdisks. Astrometry spanning 2008-2014 reveals orbital motion in both the Aab (0 23 separation) and Bab (0 095 separation) pairs, although the implied orbital periods of >300 years mean dynamical masses will not be possible in the near future. The faintest component (2M0441+2301 Bb) has an angular H-band shape, strong molecular absorption (VO, CO, H 2 O, and FeH), and shallow alkali lines, confirming its young age, late spectral type (L1 ± 1), and low temperature (≈1800 K). With individual masses of 200 50 100 -+ M Jup , 35 ± 5 M Jup , 19 ± 3 M Jup , and 9.8 ± 1.8 M Jup , 2M0441 +2301 AabBab is the lowest-mass quadruple system known. Its hierarchical orbital architecture and mass ratios imply that it formed from the collapse and fragmentation of a molecular cloud core, demonstrating that planetarymass companions can originate from a stellar-like pathway analogous to higher-mass quadruple star systems as first speculated by Todorov et al. More generally, cloud fragmentation may be an important formation pathway for the massive exoplanets that are now regularly being imaged on wide orbits.

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The Long-Term Dynamical Evolution of Planetary Systems

Cited by 69 publications

References 141 publications

Planets transiting non-eclipsing binaries

Planets transiting non-eclipsing binaries

Long-term stability of the HR 8799 planetary system without resonant lock

NEAR-INFRARED SPECTROSCOPY OF 2M0441+2301 AabBab: A QUADRUPLE SYSTEM SPANNING THE STELLAR TO PLANETARY MASS REGIMES

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