Disrupting primordial planet signatures: the close encounter of two single-planet exosystems in the Galactic disc

Aims. We perform a simulation using the Astrophysical Multipurpose Software Environment of the Orion Trapezium star cluster in which the evolution of the stars and the dynamics of planetary systems are taken into account. Methods. The initial conditions from earlier simulations were selected in which the size and mass distributions of the observed circumstellar disks in this cluster are satisfactorily reproduced. Four, five, or size planets per star were introduced in orbit around the 500 solar-like stars with a maximum orbital separation of 400 au.Results. Our study focuses on the production of free-floating planets. A total of 357 become unbound from a total of 2522 planets in the initial conditions of the simulation. Of these, 281 leave the cluster within the crossing timescale of the star cluster; the others remain bound to the cluster as free-floating intra-cluster planets. Five of these free-floating intra-cluster planets are captured at a later time by another star.Conclusions. The two main mechanisms by which planets are lost from their host star, ejection upon a strong encounter with another star or internal planetary scattering, drive the evaporation independent of planet mass of orbital separation at birth. The effect of small perturbations due to slow changes in the cluster potential are important for the evolution of planetary systems. In addition, the probability of a star to lose a planet is independent of the planet mass and independent of its initial orbital separation. As a consequence, the mass distribution of free-floating planets is indistinguishable from the mass distribution of planets bound to their host star.Article number, page 3 of 17

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“…6 and Fig. 7: the ejection of planets is independent of their mass (see also Malmberg et al 2011;Veras & Moeckel 2012).…”

Section: Production Of Free-floating Planetsmentioning

confidence: 95%

Survivability of planetary systems in young and dense star clusters

Elteren

Zwart

Pelupessy

et al. 2019

A&A

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“…We also do not include flybys from passing stars, for both computational reasons and so that we can focus on the unpacking process. In reality, we should expect, over the age of the Universe, one Galactic field star to come within a few hundred au of another (Zakamska & Tremaine 2004;Veras & Moeckel 2012). However, post-main-sequence mass loss occurs for just a small fraction of this time.…”

Section: Terrestrial Planetsmentioning

confidence: 99%

Detectable close-in planets around white dwarfs through late unpacking

Veras

Gänsicke

2014

Monthly Notices of the Royal Astronomical Society

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120

129

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Although 25%-50% of white dwarfs (WDs) display evidence for remnant planetary systems, their orbital architectures and overall sizes remain unknown. Vibrant close-in (≃ 1R ⊙ ) circumstellar activity is detected at WDs spanning many Gyrs in age, suggestive of planets further away. Here we demonstrate how systems with 4 and 10 closely-packed planets that remain stable and ordered on the main sequence can become unpacked when the star evolves into a WD and experience pervasive inward planetary incursions throughout WD cooling. Our full-lifetime simulations run for the age of the Universe and adopt main sequence stellar masses of 1.5M ⊙ , 2.0M ⊙ and 2.5M ⊙ , which correspond to the mass range occupied by the progenitors of typical present-day WDs. These results provide (i) a natural way to generate an ever-changing dynamical architecture in post-main-sequence planetary systems, (ii) an avenue for planets to achieve temporary close-in orbits that are potentially detectable by transit photometry, and (iii) a dynamical explanation for how residual asteroids might pollute particularly old WDs.

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“…In some cases, however, one might be able to utilize the impulse approximation. This approximation holds if both the perturber is quick and the encounter time-scale is shorter than the moon's orbital period about the planet (Zakamska & Tremaine 2004;Veras & Moeckel 2012;Jackson et al 2014). This condition is…”

Section: A P P E N D I X C : a Na Ly T I C A P P Rox I M At I O N Smentioning

confidence: 99%

Liberating exomoons in white dwarf planetary systems

Payne¹,

Veras²,

Holman³

et al. 2016

Mon. Not. R. Astron. Soc.

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Previous studies indicate that more than a quarter of all white dwarf (WD) atmospheres are polluted by remnant planetary material, with some WDs being observed to accrete the mass of Pluto in 10 6 yr. The short sinking time-scale for the pollutants indicates that the material must be frequently replenished. Moons may contribute decisively to this pollution process if they are liberated from their parent planets during the post-main-sequence evolution of the planetary systems. Here, we demonstrate that gravitational scattering events amongst planets in WD systems easily trigger moon ejection. Repeated close encounters within tenths of planetary Hill radii are highly destructive to even the most massive, close-in moons. Consequently, scattering increases both the frequency of perturbing agents in WD systems, as well as the available mass of polluting material in those systems, thereby enhancing opportunities for collision and fragmentation and providing more dynamical pathways for smaller bodies to reach the WD. Moreover, during intense scattering, planets themselves have pericentres with respect to the WD of only a fraction of an astronomical unit, causing extreme Hill-sphere contraction, and the liberation of moons into WD-grazing orbits. Many of our results are directly applicable to exomoons orbiting planets around main-sequence stars.

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Disrupting primordial planet signatures: the close encounter of two single-planet exosystems in the Galactic disc

Cited by 41 publications

References 59 publications

Survivability of planetary systems in young and dense star clusters

Survivability of planetary systems in young and dense star clusters

Detectable close-in planets around white dwarfs through late unpacking

Liberating exomoons in white dwarf planetary systems

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