The fragility of the terrestrial planets during a giant-planet instability

Kaib, Nathan A.; Chambers, John E.

doi:10.1093/mnras/stv2554

Cited by 91 publications

(99 citation statements)

References 34 publications

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“…Our calculations thus refer to the cometary component of the LHB in case the timing of the planetary migration is relevant for offering an explanation of the LHB . In case the migration occurred at a much earlier time (Kaib & Chambers 2016;Weaver et al 2016), our results would refer to a much earlier cometary bombardment. This would be unrelated to the LHB, and the LHB would need to be explained in a different way.…”

Section: Discussionmentioning

confidence: 90%

Cometary impact rates on the Moon and planets during the late heavy bombardment

Rickman

Wiśniowski

Gabryszewski

et al. 2017

A&A

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Context. The Nice model predicts that the trans-planetary planetesimal disk made a large or even dominant contribution to the cratering in the inner solar system during the late heavy bombardment (LHB). In the presence of evidence that lunar craters and mare basins may be mainly of asteroidal origin, there is a dilemma of the missing comets that is not yet resolved. Aims. We aim to revisit the problem of cometary impact rates on the Moon and the terrestrial planets during the LHB with a flexible model, allowing us to study the influences of physical destruction of comets, the mass of the primordial disk, and the distribution of this mass over the entire size range. Methods. We performed a Monte Carlo study of the dynamics of the cometary LHB projectiles and derive the impact rates by calculating individual collision probabilities for a huge sample of projectile orbits. We used Minimum Orbit Intersection Distances (MOIDs) according to a new scheme introduced here. Different calculations were performed using different models for the physical evolution of comet nuclei and for the properties of the primordial, trans-planetary disk. Results. Based on the capture probability of Jupiter Trojans, we find a best fit radius of the largest LHB comet impacting the Moon for a low-mass primordial disk. For this disk mass, the LHB cratering of the Moon, Mercury and Mars were dominated by asteroids. However, some smaller lunar maria were likely preceded by comet impacts. The volatile delivery to the Earth and Mars by LHB comets was much less than their water inventories. Conclusions. There is no excessive cometary cratering, if the LHB was caused by a late planetary instability in the Nice Model. The Earth and Mars obtained their water very early in their histories. The Noachian water flows on Mars cannot be attributed to the arrival of LHB-related H 2 O or CO 2 .

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Section: Discussionmentioning

confidence: 90%

Cometary impact rates on the Moon and planets during the late heavy bombardment

Rickman

Wiśniowski

Gabryszewski

et al. 2017

A&A

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“…This constrain is especially important if the instability happened late, because in this case it is strictly required that the orbits of Jupiter and Saturn experienced a discontinuity during their encounters with a third, planetary-size object (the so-called jumping-Jupiter model; Morbidelli et al 2009Morbidelli et al , 2010Brasser et al 2009). Moreover, it was shown that only a small measure of the jumping-Jupiter models is fully satisfactory (e.g., Kaib & Chambers 2016, while most lead to an excessive excitation of the terrestrial planet orbits. The constraint on the jumping-Jupiter model would be relaxed if the instability happened early.…”

Section: Caveats For T Inst < 100 Myrmentioning

confidence: 99%

Modeling the Historical Flux of Planetary Impactors

Nesvorný¹,

Roig²,

Bottke³

2017

117

221

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The impact cratering record of the Moon and the terrestrial planets provides important clues about the formation and evolution of the Solar System. Especially intriguing is the epoch ≃3.8-3.9 Gyr ago (Ga), known as the Late Heavy Bombardment (LHB), when the youngest lunar basins such as Imbrium and Orientale formed. The LHB was suggested to originate from a slowly declining impactor flux or from a late dynamical instability. Here we develop a model for the historical flux of large asteroid impacts and discuss how it depends on various parameters, including the time and nature of the planetary migration/instability. We find that the asteroid impact flux dropped by 1 to 2 orders of magnitude during the first 1 Gyr and remained relatively unchanged over the last 3 Gyr. The early impacts were produced by asteroids whose orbits became excited during the planetary migration/instability, and by those originating from the inner extension of the main belt (E-belt; semimajor axis 1.6 < a < 2.1 au). The inner main belt dominated the asteroid impact record after ∼3-4 Ga. The profiles obtained for the early and late versions of the planetary instability initially differ, but end up being similar after ∼3 Ga. Thus, the time of the instability can only be determined by considering the cratering and other constraints during the first ≃1.5 Gyr of the Solar System history. Our absolute calibration of the impact flux indicates that asteroids were probably not responsible for the LHB, independently of whether the instability happened early or late, because the calibrated flux is not large enough to explain Imbrium/Orientale and a significant share of large lunar craters. Comets and leftovers of the terrestrial planet formation provided additional, and probably dominant source of impacts during early epochs. The cometary impacts occur during a narrow interval after the instability and would not be recorded on surfaces if the planetary instability happened early.-2 -

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“…These very late instabilities in our systems occur even though the orbits of Jupiter and Saturn are effectively fixed for the entire integration. The rate of instabilities would likely be significantly higher if the orbits of the gas giants evolved substantially over time (Brasser et al 2009;Agnor & Lin 2012;Brasser et al 2013;Kaib & Chambers 2016). In Figure 5, we look at the mass distributions for the last planet lost from each system with an instability after t = 200 Myrs.…”

Section: System Evolution Beyond 200 Myrsmentioning

confidence: 99%

Prevalence of chaos in planetary systems formed through embryo accretion

Clement¹,

Kaib²

2017

Icarus

Self Cite

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The formation of the solar system's terrestrial planets has been numerically modeled in various works, and many other studies have been devoted to characterizing our modern planets' chaotic dynamical state. However, it is still not known whether our planets fragile chaotic state is an expected outcome of terrestrial planet accretion. We use a suite of numerical simulations to present a detailed analysis and characterization of the dynamical chaos in 145 different systems produced via terrestrial planet formation in Kaib & Cowan (2015). These systems were created in the presence of a fully formed Jupiter and Saturn, using a variety of different initial conditions. They are not meant to provide a detailed replication of the actual present solar system, but rather serve as a sample of similar systems for comparison and analysis. We find that dynamical chaos is prevalent in roughly half of the systems we form. We show that this chaos disappears in the majority of such systems when Jupiter is removed, implying that the largest source of chaos is perturbations from Jupiter. Chaos is most prevalent in systems that form 4 or 5 terrestrial planets. Additionally, an eccentric Jupiter and Saturn is shown to enhance the prevalence of chaos in systems. Furthermore, systems in our sample with a center of mass highly concentrated between ∼0.8-1.2 AU generally prove to be less chaotic than systems with more exotic mass distributions. Through the process of evolving systems to the current epoch, we show that late instabilities are quite common in our systems. Of greatest interest, many of the sources of chaos observed in our own solar system (such as the secularly driven chaos between Mercury and Jupiter) are shown to be common outcomes of terrestrial planetary formation. Thus, consistent with previous studies such as Laskar (1996), the solar system's marginally stable, chaotic state may naturally arise from the process of terrestrial planet formation.

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The fragility of the terrestrial planets during a giant-planet instability

Cited by 91 publications

References 34 publications

Cometary impact rates on the Moon and planets during the late heavy bombardment

Cometary impact rates on the Moon and planets during the late heavy bombardment

Modeling the Historical Flux of Planetary Impactors

Prevalence of chaos in planetary systems formed through embryo accretion

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