Prospecting for exo-Earths in multiple planet systems with a gas giant

Agnew, Matthew T.; Maddison, Sarah; Horner, Jonathan

doi:10.1093/mnras/sty2509

Cited by 19 publications

(38 citation statements)

References 57 publications

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“…For discs which are dispersed more rapidly than this, giant planet formation may be curtailed. Giant planets play an important role in planetary dynamics and the distribution of molecules towards the inner terrestrial planets (e.g Chambers & Wetherill 2001;Batygin & Laughlin 2015;Agnew et al 2018). Hence, quantifying the factors that determine PPD dispersal are important in understanding observed exoplanet architectures and chemistry.…”

Section: Introductionmentioning

confidence: 99%

A solution to the proplyd lifetime problem

Winter

Clarke

Rosotti

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Protoplanetary discs (PPDs) in the Orion Nebula Cluster (ONC) are irradiated by UV fields from the massive star θ 1 C. This drives thermal winds, inducing mass loss rates of up to M wind ∼ 10 −7 M yr −1 in the 'proplyds' (ionised PPDs) close to the centre. For the mean age of the ONC and reasonable initial PPD masses, such mass loss rates imply that discs should have been dispersed. However, ∼ 80% of stars still exhibit a NIR excess, suggesting that significant circumstellar mass remains. This 'proplyd lifetime problem' has persisted since the discovery of photoevaporating discs in the core of the ONC by O' Dell & Wen (1994). In this work, we demonstrate how an extended period of star formation can solve this problem. Coupling N-body calculations and a viscous disc evolution model, we obtain high disc fractions at the present day. This is partly due to the migration of older stars outwards, and younger stars inwards such that the most strongly irradiated PPDs are also the youngest. We show how the disc mass distribution can be used to test the recent claims in the literature for multiple stellar populations in the ONC. Our model also explains the recent finding that host mass and PPD mass are only weakly correlated, in contrast with other regions of similar age. We conclude that the status of the ONC as the archetype for understanding the influence of environment on planet formation is undeserved; the complex star formation history (involving star formation episodes within ∼ 0.8 Myr of the present day) results in confusing signatures in the PPD population.

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Section: Introductionmentioning

confidence: 99%

A solution to the proplyd lifetime problem

Winter

Clarke

Rosotti

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Since our simulations use massless TPs, they do not take into account mutual gravitational interactions between the planet and any companion -represented by the TPs -orbit. In order to use TPs to predict the stability of massive bodies with any confidence (such as demonstrated by Agnew et al 2017Agnew et al , 2018b, we only need to consider those TPs that are not excited (in other words, the gravitational influence of the known exoplanet is not destabilising it). The gravitational influence of the less massive Earth-mass planet is also unlikely to perturb the known exoplanet in this scenario.…”

Section: Discussionmentioning

confidence: 99%

“…When a multiple planet system is discovered, we can utilise our tool to dynamically assess the stability of the system given the inferred orbital parameters. While our approach will miss more complex destabilising behaviour (such as the influence of secular resonant interactions as demonstrated by Agnew et al 2018b), it can conservatively assess the dynamical stability of a system "on the fly". Demonstrating instability using a conservative approach would suggest further observations are required to better constrain the orbital parameters of the planets, or to reassess the number of planets in the system in the cases of potential eccentricity harmonics and aliasing Anglada-Escudé & Dawson 2010;Wittenmyer et al 2013).…”

Section: Dynamical Predictionsmentioning

confidence: 99%

“…The inference of stability is determined as outlined in section 3: below the conservative line corresponds with the unexcited, Eccentricity, e 1:10 1:5 1:4 1:3 2:5 1:2 2:3 1:1 3:2 2:1 5:2 3:1 4: Eccentricity, e 1:5 1:4 1:3 2:5 1:2 2:3 1:1 3:2 2:1 5:2 3:1 4:1 5:1 10:1 Figure 7. A comparison between the predictions made using our method, and a previously run numerical simulation conducted by Agnew et al (2018b) for HD 5319. For each planet we overlay its stability signature and assess the location of the other planet with respect to the first.…”

Section: Multiple Planet Stabilitymentioning

confidence: 99%

“…We test the robustness our stability signature predictions with the dynamical stability of systems found through numerical simulations. Agnew et al (2018b) conducted such a study, simulating all multiple planet systems with a gas giant within the then known exoplanet population for 10 8 years in order to assess their dynamical stability. Figure 7 shows the HD 5319 system, which Agnew et al (2018b) found to be dynamically unstable.…”

Section: Multiple Planet Stabilitymentioning

confidence: 99%

See 2 more Smart Citations

Predicting multiple planet stability and habitable zone companions in the TESS era

Agnew

Maddison

Horner

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present an approach that is able to both rapidly assess the dynamical stability of multiple planet systems, and determine whether an exoplanet system would be capable of hosting a dynamically stable Earth-mass companion in its habitable zone. We conduct a suite of numerical simulations using a swarm of massless test particles in the vicinity of the orbit of a massive planet, in order to develop a predictive tool which can be used to achieve these desired outcomes. In this work, we outline both the numerical methods we used to develop the tool, and demonstrate its use. We find that the test particles survive in systems either because they are unperturbed due to being so far removed from the massive planet, or due to being trapped in stable mean motion resonant orbits with the massive planet. The resulting unexcited test particle swarm produces a unique signature in (a,e) space that represents the stable regions within the system. We are able to scale and translate this stability signature, and combine several together in order to conservatively assess the dynamical stability of newly discovered multiple planet systems. We also assess the stability of a system's habitable zone and determine whether an Earth-mass companion could remain on a stable orbit, without the need for exhaustive numerical simulations.

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Updated studies on exomoons in the HD 23079 system

Jagtap

Quarles

Cuntz

2021

Publ. Astron. Soc. Aust.

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We re-evaluate the outer edge of orbital stability for possible exomoons orbiting the radial velocity planet discovered in the HD 23079 system. In this system, a solar-type star hosts a Jupiter-mass planet in a nearly circular orbit in the outer stellar habitable zone. The outer stability limit of exomoons is deduced using N-body and tidal migration simulations considering a large range of initial conditions, encompassing both prograde and retrograde orbits. In particular, we extend previous works by evaluating many values in the satellite mean anomaly to identify and exclude regions of quasi-stability. Future observations of this system can make use of our results through a scale factor relative to the currently measured minimum mass. Using a constant time lag tidal model (Hut 1981), we find that plausible tidal interactions within the system are insufficient to induce significant outward migration toward the theoretical stability limit. While current technologies are incapable of detecting exomoons in this system, we comment on the detectability of putative moons through Doppler monitoring within direct imaging observations in view of future research capacities.

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Prospecting for exo-Earths in multiple planet systems with a gas giant

Cited by 19 publications

References 57 publications

A solution to the proplyd lifetime problem

A solution to the proplyd lifetime problem

Predicting multiple planet stability and habitable zone companions in the TESS era

Updated studies on exomoons in the HD 23079 system

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