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Rogerio Deienno

Publications and source records attributed to Rogerio Deienno.

At least 37 records · Page 2Linked to original sources
arXiv2023

NEOMOD: A New Orbital Distribution Model for Near Earth Objects

Near Earth Objects (NEOs) are a transient population of small bodies with orbits near or in the terrestrial planet region. They represent a mid-stage in the dynamical cycle of asteroids and comets, which starts with their removal from the respective source regions -- the main belt and trans-Neptunian scattered disk -- and ends as bodies impact planets, disintegrate near the Sun, or are ejected from the Solar System. Here we develop a new orbital model of NEOs by numerically integrating asteroid orbits from main belt sources and calibrating the results on observations of the Catalina Sky Survey. The results imply a size-dependent sampling of the main belt with the $ν_6$ and 3:1 resonances producing $\simeq 30$\% of NEOs with absolute magnitudes $H = 15$ and $\simeq 80$\% of NEOs with $H = 25$. Hence, the large and small NEOs have different orbital distributions. The inferred flux of $H<18$ bodies into the 3:1 resonance can be sustained only if the main-belt asteroids near the resonance drift toward the resonance at the maximal Yarkovsky rate ($\simeq 2 \times 10^{-4}$ au Myr$^{-1}$ for diameter $D=1$ km and semimajor axis $a=2.5$~au). This implies obliquities $θ\simeq 0^\circ$ for $a<2.5$~au and $θ\simeq 180^\circ$ for $a>2.5$~au, both in the immediate neighborhood of the resonance (the same applies to other resonances as well). We confirm the size-dependent disruption of asteroids near the Sun found in previous studies. An interested researcher can use the publicly available NEOMOD Simulator to generate user-defined samples of NEOs from our model.

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arXiv2023

Early Bombardment of the Moon: Connecting the Lunar Crater Record to the Terrestrial Planet Formation

The lunar crater record features $\sim 50$ basins. The radiometric dating of Apollo samples indicates that the Imbrium basin formed relatively late -- from the planet formation perspective -- some $\simeq 3.9$ Ga. Here we develop a dynamical model for impactors in the inner solar system to provide context for the interpretation of the lunar crater record. The contribution of cometary impactors is found to be insignificant. Asteroids produced most large impacts on the terrestrial worlds in the last $\simeq 3$ Gyr. The great majority of early impactors were rocky planetesimals left behind at $\sim 0.5$--1.5 au after the terrestrial planet accretion. The population of terrestrial planetesimals was reduced by disruptive collisions in the first $t \sim 20$ Myr after the gas disk dispersal. We estimate that there were $\sim 4 \times 10^5$ diameter $d>10$ km bodies when the Moon formed (total planetesimal mass $\sim 0.015$ $M_{\rm Earth}$ at $t \sim 50$ Myr). The early bombardment of the Moon was intense. To accommodate $\sim 50$ known basins, the lunar basins that formed before $\simeq 4.35$--4.41 Ga must have been erased. The late formation of Imbrium occurs with a $\sim 15$--35\% probability in our model. About 20 $d>10$-km bodies were expected to hit the Earth between 2.5 and 3.5 Ga, which is comparable to the number of known spherule beds in the late Archean. We discuss implications of our model for the lunar/Martian crater chronologies, Late Veneer, and noble gases in the Earth atmosphere.

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arXiv2022

Formation of Lunar Basins from Impacts of Leftover Planetesimals

The Moon holds important clues to the early evolution of the Solar System. Some 50 impact basins (crater diameter D>300 km) have been recognized on the lunar surface, implying that the early impact flux was much higher than it is now. The basin-forming impactors were suspected to be asteroids released from an inner extension of the main belt (1.8-2.0 au). Here we show that most impactors were instead rocky planetesimals left behind at 0.5-1.5 au after the terrestrial planet accretion. The number of basins expected from impacts of leftover planetesimals largely exceeds the number of known lunar basins, suggesting that the first 200 Myr of impacts is not recorded on the lunar surface. The Imbrium basin formation (age 3.92 Gyr; impactor diameter d~100 km) occurs with a 15-35% probability in our model. Imbrium must have formed unusually late to have only two smaller basins (Orientale and Schrodinger) forming afterwards. The model predicts 20 d>10-km impacts on the Earth 2.5-3.5 Gyr ago (Ga), which is comparable to the number of known spherule beds in the late Archean.

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arXiv2022

Rethinking the role of the giant planet instability in terrestrial planet formation models

Advances in computing power and numerical methodologies over the past several decades sparked a prolific output of dynamical investigations of the late stages of terrestrial planet formation. Among other peculiar inner solar system qualities, the ability of simulations to reproduce the small mass of Mars within the planets' geochemically inferred accretion timescale of <10 Myr after the appearance of calcium aluminum-rich inclusions (CAIs) is arguably considered the gold standard for judging evolutionary hypotheses. At present, a number of independent models are capable of consistently generating Mars-like planets and simultaneously satisfying various important observational and geochemical constraints. However, all models must still account for the effects of the epoch of giant planet migration and orbital instability; an event which dynamical and cosmochemical constraints indicate occurred within the first 100 Myr after nebular gas dispersal. If the instability occurred in the first few Myr of this window, the disturbance might have affected the bulk of Mars' growth. In this manuscript, we turn our attention to a scenario where the instability took place after t=50 Myr. Specifically, we simulate the instability's effects on three nearly-assembled terrestrial systems that were generated via previous embryo accretion models and contain three large proto-planets with orbits interior to a collection of ~Mars-mass embryos and debris. While the instability consistently triggers a Moon-forming impact and efficiently removes excessive material from the Mars-region in our models, we find that our final systems are too dynamically excited and devoid of Mars and Mercury analogs. Thus, we conclude that, while possible, our scenario is far more improbable than one where the instability either occurred earlier, or at a time where Earth and Venus' orbits were far less dynamically excited.

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arXiv2022

Implications of Jupiter Inward Gas-Driven Migration for the Inner Solar System

The migration history of Jupiter in the sun's natal disk remains poorly constrained. Here we consider how Jupiter's migration affects small-body reservoirs and how this constrains its original orbital distance from the Sun. We study the implications of large-scale and inward radial migration of Jupiter for the inner solar system while considering the effects of collisional evolution of planetesimals. We use analytical prescriptions to simulate the growth and migration of Jupiter in the gas disk. We assume the existence of a planetesimal disk inside Jupiter's initial orbit. This planetesimal disk received an initial total mass and size-frequency distribution (SFD). Planetesimals feel the effects of aerodynamic gas drag and collide with one another, mostly while shepherded by the migrating Jupiter. Our main goal is to measure the amount of mass in planetesimals implanted into the main asteroid belt (MAB) and the SFD of the implanted population. We also monitor the amount of dust produced during planetesimal collisions. We find that the SFD of the planetesimal population implanted into the MAB tends to resemble that of the original planetesimal population interior to Jupiter. We also find that unless very little or no mass existed between 5 au and Jupiter's original orbit, it would be difficult to reconcile the current low mass of the MAB with the possibility that Jupiter migrated from distances beyond 15 au. This is because the fraction of the original disk mass that gets implanted into the MAB is very large. Finally, we discuss the implications of our results in terms of dust production to the so-called NC-CC isotopic dichotomy.

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arXiv2022

Implications for the collisional strength of Jupiter Trojans from the Eurybates family

In this work, we model the collisional evolution of the Jupiter Trojans and determined under which conditions the Eurybates-Queta system survives. We show that the collisional strength of the Jupiter Trojans and the age of the Eurybates family and by extension Queta are correlated. The collisional grinding of the Jupiter Trojan population over 4.5 Gy results in a size-frequency distribution (SFD) that remains largely unaltered at large sizes (>10 km) but is depleted at small sizes (10 m to 1 km). This results in a turnover in the SFD, the location of which depends on the collisional strength of the material. It is to be expected that the Trojan SFD bends between 1 and 10 km. Based on the SFD of the Eurybates family, we find that the family was likely the result of a catastrophic impact onto a 100 km rubble pile target. This corresponds to objects with a rather low collisional strength (10 times weaker than that of basaltic material studied in Benz & Asphaug1999). Assuming this weak strength, and an initial cumulative slope of the size frequency distribution of 2.1 between diameters of 2 m and 100 km when the Trojans were captured, the existence of Queta, the satellite of Eurybates, implies an upper limit for the family age of 3.7 Gy. Alternatively, we demonstrate that an unconventional collisional strength with a minimum at 20 m is a plausible candidate to ensure the survival of Queta over the age of the Solar System. Finally, we show how different collisional histories change the expected number of craters on the targets of the Lucy mission and that Lucy will be able to differentiate between them.

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arXiv2021

Planetesimal rings as the cause of the Solar System's planetary architecture

Astronomical observations reveal that protoplanetary disks around young stars commonly have ring- and gap-like structures in their dust distributions. These features are associated with pressure bumps trapping dust particles at specific locations, which simulations show are ideal sites for planetesimal formation. Here we show that our Solar System may have formed from rings of planetesimals -- created by pressure bumps -- rather than a continuous disk. We model the gaseous disk phase assuming the existence of pressure bumps near the silicate sublimation line (at $T \sim$1400~K), water snowline (at $T \sim$170~K), and CO-snowline (at $T \sim$30~K). Our simulations show that dust piles up at the bumps and forms up to three rings of planetesimals: a narrow ring near 1~au, a wide ring between $\sim$3-4~au and $\sim$10-20~au, and a distant ring between $\sim$20~au and $\sim$45~au. We use a series of simulations to follow the evolution of the innermost ring and show how it can explain the orbital structure of the inner Solar System and provides a framework to explain the origins of isotopic signatures of Earth, Mars and different classes of meteorites. The central ring contains enough mass to explain the rapid growth of the giant planets' cores. The outermost ring is consistent with dynamical models of Solar System evolution proposing that the early Solar System had a primordial planetesimal disk beyond the current orbit of Uranus.

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arXiv2021

The "Breaking The Chains" migration model for super-Earths formation: the effect of collisional fragmentation

Planets between 1-4 Earth radii with orbital periods <100 days are strikingly common. The migration model proposes that super-Earths migrate inwards and pile up at the disk inner edge in chains of mean motion resonances. After gas disk dispersal, simulations show that super-Earth's gravitational interactions can naturally break their resonant configuration leading to a late phase of giant impacts. The instability phase is key to matching the orbital spacing of observed systems. Yet, most previous simulations have modelled collisions as perfect accretion events, ignoring fragmentation. In this work, we investigate the impact of imperfect accretion on the breaking the chains scenario. We performed N-body simulations starting from distributions of planetary embryos and modelling the effects of pebble accretion and migration in the gas disk. Our simulations also follow the long-term dynamical evolution of super-Earths after the gas disk dissipation. We compared the results of simulations where collisions are treated as perfect merging events with those where imperfect accretion and fragmentation are allowed. We concluded that the perfect accretion is a suitable approximation in this regime, from a dynamical point of view. Although fragmentation events are common, only ~10% of the system mass is fragmented during a typical "late instability phase", with fragments being mostly reacreted by surviving planets. This limited total mass in fragments proved to be insufficient to alter qualitatively the final system dynamical configuration -- e.g. promote strong dynamical friction or residual migration -- compared to simulations where fragmentation is neglected.

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arXiv2021

iSyMBA: A Symplectic Massive Bodies Integrator with Planets Interpolation

A planetary instability occurring at time $<100$ My after formation of the giant planets in our solar system can be responsible for some characteristics of the inner solar system. However, the actual influence of the instability on the terrestrial planet formation is not well understood. The simulations of terrestrial planet formation are very CPU-expensive, and this limits the exploration of different instability scenarios. To include the effects of the giant planets instability in the simulations of terrestrial planets formation in a feasible way, we approach the problem in two steps. First, we model and record an evolution of the giant planets that replicates the present outer solar system in the end. Then, we use that orbital record, properly interpolated, as the input for a second step to simulate its effects on the terrestrial planet formation. For this second step, we developed iSyMBA, a symplectic massive bodies algorithm, where ``i'' stands for interpolation. iSyMBA is a very useful code to accurately evaluate the effects of planetary instabilities on minor body reservoirs, while accounting for close encounters among massive objects. We provide a detailed description of how iSyMBA was developed and implemented to study terrestrial planet formation. Adapting iSyMBA for other problems that demand interpolation from previous simulations can be done following the method described here.

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arXiv2021

Born extra-eccentric: A broad spectrum of primordial configurations of the gas giants that match their present-day orbits

In a recent paper we proposed that the giant planets' primordial orbits may have been eccentric (~0.05), and used a suite of dynamical simulations to show outcomes of the giant planet instability that are consistent with their present-day orbits. In this follow-up investigation, we present more comprehensive simulations incorporating superior particle resolution, longer integration times, and eliminating our prior means of artificially forcing instabilities to occur at specified times by shifting a planets' position in its orbit. While we find that the residual phase of planetary migration only minimally alters the the planets' ultimate eccentricities, our work uncovers several intriguing outcomes in realizations where Jupiter and Saturn are born with extremely large eccentricities (~0.10 and ~0.25, respectively). In successful simulations, the planets' orbits damp through interactions with the planetesimal disk prior to the instability, thus loosely replicating the initial conditions considered in our previous work. Our results therefore suggest an even wider range of plausible evolutionary pathways are capable of replicating Jupiter and Saturn's modern orbital architecture.

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arXiv2020

The Role of Early Giant Planet Instability in the Terrestrial Planet Formation

The terrestrial planets are believed to have formed by violent collisions of tens of lunar- to Mars-size protoplanets at time t<200 Myr after the protoplanetary gas disk dispersal (t_0). The solar system giant planets rapidly formed during the protoplanetary disk stage and, after t_0, radially migrated by interacting with outer disk planetesimals. An early (t<100 Myr) dynamical instability is thought to have occurred with Jupiter having gravitational encounters with a planetary-size body, jumping inward by ~0.2-0.5 au, and landing on its current, mildly eccentric orbit. Here we investigate how the giant planet instability affected formation of the terrestrial planets. We study several instability cases that were previously shown to match many solar system constraints. We find that resonances with the giant planets help to remove solids available for accretion near ~1.5 au, thus stalling the growth of Mars. It does not matter, however, whether the giant planets are placed on their current orbits at t_0 or whether they realistically evolve in one of our instability models; the results are practically the same. The tight orbital spacing of Venus and Earth is difficult to reproduce in our simulations, including cases where bodies grow from a narrow annulus at 0.7-1 au, because protoplanets tend to radially spread during accretion. The best results are obtained in the narrow-annulus model when protoplanets emerging from the dispersing gas nebula are assumed to have (at least) the Mars mass. This suggests efficient accretion of the terrestrial protoplanets during the first ~10 Myr of the solar system.

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arXiv2020

Efficiency characterization of the V-shape asteroid family detection method

Following the break up of a parent body, the Yarkovsky effect causes asteroid family members to spread in orbital semimajor axis with a rate often inversely proportional to their diameter. This size dependent semimajor axis drift causes family members to form structures in the semimajor axis vs inverse diameter plane that have the shape of the letter V. The V-shape method consists in finding the borders of such V-shapes of unknown center and opening. Although successfully employed to find some very old families in the inner main asteroid belt, the V-shape searching method is very sensitive to many parameters. In this work, we first created and evolved a synthetic asteroid family over billions of years. Then, by adding uncertainties to semimajor axis and diameter of the evolved synthetic family components, we randomly generated additional 99 similar, but not perfectly V-shaped, family clones. We chose a fairly low initial velocity dispersion of 20 m/s for our family. Thus, we can more easily relate the spreading in semimajor axis with the family's age (slope of the evolving V). A synthetic background with an initially randomly distributed components was also created and evolved for 100 Myr. Thus, by setting different levels of ratio of the synthetic family and background asteroids, we derived a detection efficiency map for the V-shape method and determined how sensitive the results can be based on signal-to-noise levels. We also determined optimal parameter values for the method's efficiency. We found that, families older than ~3 Gyr are likely undetectable, with a method efficiency of 50% or less, whereas younger families (0.5--2.5 Gyr) are more easily detected by the method, with an efficiency of >80%.

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arXiv2020

Born eccentric: constraints on Jupiter and Saturn's pre-instability orbits

An episode of dynamical instability is thought to have sculpted the orbital structure of the outer solar system. When modeling this instability, a key constraint comes from Jupiter's fifth eccentric mode (quantified by its amplitude M55), which is an important driver of the solar system's secular evolution. Starting from commonly-assumed near-circular orbits, the present-day giant planets' architecture lies at the limit of numerically generated systems, and M55 is rarely excited to its true value. Here we perform a dynamical analysis of a large batch of artificially triggered instabilities, and test a variety of configurations for the giant planets' primordial orbits. In addition to more standard setups, and motivated by the results of modern hydrodynamical simulations of the giant planets' evolution within the primordial gaseous disk, we consider the possibility that Jupiter and Saturn emerged from the nebular gas locked in 2:1 resonance with non-zero eccentricities. We show that, in such a scenario, the modern Jupiter-Saturn system represents a typical simulation outcome, and M55 is commonly matched. Furthermore, we show that Uranus and Neptune's final orbits are determined by a combination of the mass in the primordial Kuiper belt and that of an ejected ice giant.

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arXiv2020

Linking planetary embryo formation to planetesimal formation II: The impact of pebble accretion in the terrestrial planet zone

The accretion of pebbles on planetary cores has been widely studied in recent years and is found to be a highly effective mechanism for planetary growth. While most studies assume planetary cores as an initial condition in their simulation, the question how, where and when these cores form is often neglected. We study the impact of pebble accretion during the formation phase and subsequent evolution of planetary embryos in the early stages of circumstellar disk evolution. In doing so we aim to quantify the timescales and local dependency of planetary embryo formation, based on the solid evolution of the disk. We connect a one dimensional two population model for solid evolution and pebble flux regulated planetesimal formation to the N-body code LIPAD. In our study we focus on the growth of planetesimals with an initial size of 100 km in diameter by planetesimal collisions and pebble accretion for the first 1 million years of a viscously evolving disk. We compare 18 different N-body simulations in which we vary the total planetesimal mass after 1 million years, the surface density profile of the planetesimal disk, the radial pebble flux and the possibility of pebble accretion. Pebble accretion leads to the formation of fewer, but substantially more massive embryos. The area of possible embryo formation is weakly influenced by the accretion of pebbles and the innermost embryos tend to form slightly earlier compared to the simulations in which pebble accretion is neglected. Pebble accretion strongly enhances the formation of super earths in the terrestrial planet region, but it does not enhance the formation of embryos at larger distances.

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arXiv2020

Linking planetary embryo formation to planetesimal formation I: The impact of the planetesimal surface density in the terrestrial planet zone

The growth time scales of planetary embryos and their formation process are imperative for our understanding on how planetary systems form and develop. They determine the subsequent growth mechanisms during the life stages of a circumstellar disk. We quantify the timescales and spatial distribution of planetary embryos via collisional growth and fragmentation of dynamically forming 100km sized planetesimals. In our study, the formation timescales of viscous disk evolution and planetesimal formation are linked to the formation of planetary embryos in the terrestrial planet zone. We connect a one dimensional model for viscous gas evolution, dust and pebble dynamics and pebble flux regulated planetesimal formation to the N-body code LIPAD. Our framework enables us to study the formation, growth, fragmentation and evolution of planetesimals with an initial size of 100km in diameter for the first million years of a viscous disk. Our study shows the effect of the planetesimal surface density evolution on the preferential location and timescales of planetary embryo formation. A one dimensional analytically derived model for embryo formation based on the local planetesimal surface density evolution is presented. This model manages to reproduce the spatial distribution, formation rate and total number of planetary embryos at a fraction of the computational cost of the N-body simulations. The formation of planetary embryos in the terrestrial planet zone occurs simultaneously to the formation of planetesimals. The local planetesimal surface density evolution and the orbital spacing of planetary embryos in the oligarchic regime serve well as constraints to model planetary embryo formation analytically. Our embryo formation model will be a valuable asset in future studies regarding planet formation.

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arXiv2018

The excitation of a primordial cold asteroid belt as an outcome of the planetary instability

The main asteroid belt (MB) is low in mass but dynamically excited. Here we propose a new mechanism to excite the MB during the giant planet ('Nice model') instability, which is expected to have featured repeated close encounters between Jupiter and one or more ice giants ('Jumping Jupiter' -- JJ). We show that, when Jupiter temporarily reaches a high enough level of excitation, both in eccentricity and inclination it induces strong forced vectors of eccentricity and inclination across the MB region. Because during the JJ instability Jupiter's orbit `jumps' around, the forced vectors keep changing both in magnitude and phase throughout the whole MB region. The entire cold primordial MB is thus excited as a natural outcome of the JJ instability. The level of such an excitation, however, is typically larger than the current orbital excitation observed in the MB. We show that the subsequent evolution of the Solar System is capable of reshaping the resultant over-excited MB to its present day orbital state, and that a strong mass depletion ($\sim$90$\%$) is associated to the JJ instability phase and its subsequent evolution throughout the age of the Solar System.

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arXiv2017

Checking the Compatibility of the Cold Kuiper Belt with a Planetary Instability Migration Model

The origin of the orbital structure of the cold component of the Kuiper belt is still a hot subject of investigation. Several features of the solar system suggest that the giant planets underwent a phase of global dynamical instability, but the actual dynamical evolution of the planets during the instability is still debated. To explain the structure of the cold Kuiper belt, Nesvorny (2015, AJ 150,68) argued for a soft instability, during which Neptune never achieved a very eccentric orbit. Here we investigate the possibility of a more violent instability, from an initially more compact fully resonant configuration of 5 giant planets. We show that the orbital structure of the cold Kuiper belt can be reproduced quite well provided that the cold population formed in situ, with an outer edge between 44 and 45 au and never had a large mass.

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