The terrestrial planet formation paradox inferred from high-resolution N-body simulations

Woo, Jason Man Yin; Brasser, R.; Grimm, Simon L.; Timpe, Miles L.; Stadel, Joachim

doi:10.1016/j.icarus.2021.114692

Cited by 21 publications

(11 citation statements)

References 139 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Traces of such giant impacts can be found on most terrestrial planets in our Solar System, the most iconic of which is thought to lead to the formation of the Earth-Moon system (Wyatt & Jackson 2016). Estimates for the epoch of the latter event -which is thought to be one of the last giant collisions between planetary bodies in the Solar System -range between 50 and 200 million years after the condensation of calcium-aluminum rich inclusions (Lock et al 2020), more likely occurring within 80 Myr (Woo et al 2022). The migration models of the formation of super-Earths predict resulting configuration with planets in resonant chains.…”

Section: Giant Collision Related To Terrestrial Planet Formationmentioning

confidence: 99%

Mid-infrared time-domain study of recent dust production events in the extreme debris disc of TYC 4209-1322-1

Moór

Ábrahám

Kóspál

et al. 2022

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Extreme debris discs are characterized by unusually strong mid-infrared excess emission, which often proves to be variable. The warm dust in these discs is of transient nature and is likely related to a recent giant collision occurring close to the star in the terrestrial region. Here we present the results of a 877 days long, gap-free photometric monitoring performed by the Spitzer Space Telescope of the recently discovered extreme debris disc around TYC 4209-1322-1. By combining these observations with other time-domain optical and mid-infrared data, we explore the disc variability of the last four decades, with particular emphasis on the last 12 years. During the latter interval the disc showed substantial changes, the most significant was the brightening and subsequent fading between 2014 and 2018 as outlined in WISE data. The Spitzer light curves outline the fading phase and a subsequent new brightening of the disc after 2018, revealing an additional flux modulation with a period of ∼39 days on top of the long-term trend. We found that all these variations can be interpreted as the outcome of a giant collision that happened at an orbital radius of ∼0.3 au sometime in 2014. Our analysis implies that a collision on a similar scale could have taken place around 2010, too. The fact that the disc was already peculiarly dust rich 40 years ago, as implied by IRAS data, suggests that these dust production events belong to a chain of large impacts triggered by an earlier even more catastrophic collision.

show abstract

Section: Giant Collision Related To Terrestrial Planet Formationmentioning

confidence: 99%

Mid-infrared time-domain study of recent dust production events in the extreme debris disc of TYC 4209-1322-1

Moór

Ábrahám

Kóspál

et al. 2022

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…This requires limited stirring by Jupiter, in strong contrast with models where Jupiter penetrates the terrestrial planet region during its early migration (Walsh et al 2011). This scenario where Jupiter does not stir the planetesimals in the terrestrial planet zone nevertheless makes it challenging to reach Mars' current mass in N-body simulations (Woo et al 2022). In the alternative pebble accretion model for terrestrial planet formation (Johansen et al 2021), the drifting pebbles contain largely reduced iron that is later oxidized by dissolution in hot water within the growing Venus, Earth and Mars (Johansen et R core /R = 0.9 R core /R = 0.8 R core /R = 0.7 R core /R = 0.6 R core /R = 0.547 (Earth-like) pure MgSiO 3 Fig.…”

Section: Introductionmentioning

confidence: 99%

Nucleation and growth of iron pebbles explains the formation of iron-rich planets akin to Mercury

Johansen,

Dorn

2022

Preprint

View full text Add to dashboard Cite

The pathway to forming the iron-rich planet Mercury remains mysterious. Mercury's core makes up 70% of the planetary mass, which implies a significant enrichment of iron relative to silicates, while its mantle is strongly depleted in oxidized iron. The high core mass fraction is traditionally ascribed to evaporative loss of silicates, e.g. following a giant impact, but the high abundance of moderately volatile elements in the mantle of Mercury is inconsistent with reaching temperatures much above 1,000 K during its formation. Here we explore the nucleation of solid particles from a gas of solar composition that cools down in the hot inner regions of the protoplanetary disc. The high surface tension of iron causes iron particles to nucleate homogeneously (i.e., not on a more refractory substrate) under very high supersaturation. The low nucleation rates lead to depositional growth of large iron pebbles on a sparse population of nucleated iron nano-particles. Silicates in the form of iron-free MgSiO 3 nucleate at similar temperatures but obtain smaller sizes due to the much higher number of nucleated particles. This results in a chemical separation of large iron particles from silicate particles with ten times lower Stokes numbers. We propose that such conditions lead to the formation of ironrich planetesimals by the streaming instability. In this view, Mercury formed by accretion of iron-rich planetesimals with a sub-solar abundance of highly reduced silicate material. Our results imply that the iron-rich planets known to orbit the Sun and other stars are not required to have experienced mantle-stripping impacts. Instead their formation could be a direct consequence of temperature fluctuations in protoplanetary discs and chemical separation of distinct crystal species through the ensuing nucleation process.

show abstract

“…As the giant planets' gaseous compositions indicate that they formed within the lifetime of the Sun's primordial gas disk ( 1-5 Myr: Haisch et al 2001;Hernández et al 2007), their presence in simulations of the terrestrial world's ultimate accretion is essential (Chambers & Wetherill 1998;Levison & Agnor 2003). If the giant planets' orbits remain circular through the duration of terrestrial planet formation as predicted in hydrodynamical disk models (Papaloizou & Larwood 2000;Masset & Snellgrove 2001;Pierens & Nelson 2008;Zhang & Zhou 2010), the final masses of Mars and the asteroid belt are too massive by at least an order of magnitude (Chambers 2001;Raymond et al 2006Raymond et al , 2009Lykawka & Ito 2019;Woo et al 2022). However, the moderate degree of radial mixing in such a scenario also has the advantage of aiding in the replication of Earth's water content (Raymond et al 2004) and disparities between the isotopic compositions of Earth and Mars (Tang & Dauphas 2014;Dauphas 2017;Woo et al 2021b).…”

Section: Introductionmentioning

confidence: 99%

“…An additional complication on this series of events is the giant planets' acquisition of their modern, moderately eccentric orbits (Hahn & Malhotra 1999;Tsiganis et al 2005) through an epoch of mutual encounters (Morbidelli et al 2009;Nesvorný 2011). While a lowmass Mars is a regular outcome in simulations where the giant planets' inhabit their current dynamical configuration for the duration of the simulation (Raymond et al 2009;Kaib & Cowan 2015;Lykawka & Ito 2019;Woo et al 2021a;Nesvorný et al 2021), such a scenario conflicts with the predictions of many disk models of giant planet formation and early evolution Pierens & Nelson 2008;Zhang & Zhou 2010), and also cannot explain Earth and Mars' disparate compositions (Woo et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Mercury's formation within the Early Instability Scenario

Clement¹,

Chambers²,

Kaib³

et al. 2023

Preprint

View full text Add to dashboard Cite

The inner solar system's modern orbital architecture provides inferences into the epoch of terrestrial planet formation; a ∼100 Myr time period of planet growth via collisions with planetesimals and other proto-planets. While classic numerical simulations of this scenario adequately reproduced the correct number of terrestrial worlds, their semi-major axes and approximate formation timescales, they struggled to replicate the Earth-Mars and Venus-Mercury mass ratios (∼9 and 15, respectively). In a series of past independent investigations, we demonstrated that Mars' mass is possibly the result of Jupiter and Saturn's early orbital evolution, while Mercury's diminutive size might be the consequence of a primordial mass deficit in the region (potentially the result of the growing Earth's early outward migration). Here, we combine these ideas in a single modeled scenario designed to simultaneously reproduce the formation of all four terrestrial planets and the modern orbits of the giant planets in broad strokes. By evaluating our Mercury analogs' core mass fractions, masses, and orbital offsets from Venus, we favor a scenario where Mercury forms through a series of violent erosive collisions between a number of ∼Mercury-mass embryos in the inner part of the terrestrial disk. We also compare cases where the gas giants begin the simulation locked in a compact 3:2 resonant configuration to a more relaxed 2:1 orientation and find the former to be more successful. In 2:1 cases, the entire Mercury-forming region is often depleted due to strong sweeping secular resonances that also tend to overly excite the orbits of Earth and Venus as they grow. While our model is quite successful at replicating Mercury's massive core and dynamically isolated orbit, the planets' low mass remains extremely challenging to match. Indeed, the majority of our Mercury analogs have masses that are 2-4 times that of the real planet. Finally, we discuss the merits and drawbacks of alternative evolutionary scenarios and initial disk conditions (specifically a narrow annulus of material between 0.7-1.0 au). We argue that the results of our N-body accretion models are not sufficient to break degeneracies between these different models, and implore future studies to apply further cosmochemical and dynamical constraints on terrestrial planet formation models.

show abstract

The terrestrial planet formation paradox inferred from high-resolution N-body simulations

Cited by 21 publications

References 139 publications

Mid-infrared time-domain study of recent dust production events in the extreme debris disc of TYC 4209-1322-1

Mid-infrared time-domain study of recent dust production events in the extreme debris disc of TYC 4209-1322-1

Nucleation and growth of iron pebbles explains the formation of iron-rich planets akin to Mercury

Mercury's formation within the Early Instability Scenario

Contact Info

Product

Resources

About