scholarly journals Enrichment of the HR 8799 planets by minor bodies and dust

2020 ◽  
Author(s):  
Kateryna Frantseva ◽  
Michael Mueller ◽  
Petr Pokorný ◽  
Floris F. S. van der Tak ◽  
Inge Loes ten Kate
Keyword(s):  
Solar System ◽  
Total Mass ◽  
Kuiper Belt ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Refractory Materials ◽  
Exoplanetary Systems ◽  
Main Asteroid Belt ◽  
The Impact ◽  
Shed Light

<p>Are minor bodies and dust delivering volatile and/or refractory materials in exoplanetary systems?<span class="Apple-converted-space"> </span></p> <p>Around ~20% of the nearest stars are found to host analogues of the main asteroid belt and the Kuiper belt. Our aim is to study the possibility of material delivery through minor bodies and dust to the planetary surfaces. To shed light on these delivery processes we extrapolate our Solar System scenarios to the exoplanetary system HR 8799. The system is known to host four giant planets and two belts of minor bodies.</p> <p>We performed a set of N-body simulations to study the impact rates of minor bodies and dust on the HR 8799 planets. We find that the planets suffer impacts by objects from the inner and outer belt. We convert these to volatile and refractory delivery rates using our best estimates of the total mass contained in the belts and their volatile/refractory content. Over their lifetime, the four giant planets receive between 10<sup>-4</sup> and 10<sup>-3 </sup>M<sub>Earth</sub> of material from both belts. This delivery leads to volatile and refractory enrichment of the planets that may be observable. Since the four giants HR 8799 e, d, c, b are located beyond the snow line (and presumably formed there), we expect them to be born volatile-rich. Therefore any future detection of refractories might imply delivery through impacts.</p>

scholarly journals Enrichment of the HR 8799 planets by minor bodies and dust

2020 ◽  
Vol 638 ◽  
pp. A50
Author(s):  
K. Frantseva ◽  
M. Mueller ◽  
P. Pokorný ◽  
F. F. S. van der Tak ◽  
I. L. ten Kate
Keyword(s):  
Total Mass ◽  
Kuiper Belt ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Dynamical Structure ◽  
Mean Motion Resonances ◽  
Exoplanetary Systems ◽  
Test Particles ◽  
Main Asteroid Belt ◽  
The Impact

Context. In the Solar System, minor bodies and dust deliver various materials to planetary surfaces. Several exoplanetary systems are known to host inner and outer belts, analogues of the main asteroid belt and the Kuiper belt, respectively. Aims. We study the possibility that exominor bodies and exodust deliver volatiles and refractories to the exoplanets in the well-characterised system HR 8799. Methods. We performed N-body simulations to study the impact rates of minor bodies in the system HR 8799. The model consists of the host star, four giant planets (HR 8799 e, d, c, and b), 650 000 test particles representing the inner belt, and 1 450 000 test particles representing the outer belt. Moreover we modelled dust populations that originate from both belts. Results. Within a million years, the two belts evolve towards the expected dynamical structure (also derived in other works), where mean-motion resonances with the planets carve the analogues of Kirkwood gaps. We find that, after this point, the planets suffer impacts by objects from the inner and outer belt at rates that are essentially constant with time, while dust populations do not contribute significantly to the delivery process. We convert the impact rates to volatile and refractory delivery rates using our best estimates of the total mass contained in the belts and their volatile and refractory content. Over their lifetime, the four giant planets receive between 10−4 and 10−3 M⊕ of material from both belts. Conclusions. The total amount of delivered volatiles and refractories, 5 × 10−3 M⊕, is small compared to the total mass of the planets, 11 × 103 M⊕. However, if the planets were formed to be volatile-rich, their exogenous enrichment in refractory material may well be significant and observable, for example with JWST-MIRI. If terrestrial planets exist within the snow line of the system, volatile delivery would be an important astrobiological mechanism and may be observable as atmospheric trace gases.

scholarly journals No evidence for interstellar planetesimals trapped in the Solar system

2020 ◽  
Vol 497 (1) ◽  
pp. L46-L49 ◽  
Author(s):  
A Morbidelli ◽  
K Batygin ◽  
R Brasser ◽  
S N Raymond
Keyword(s):  
Solar System ◽  
Oort Cloud ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Interstellar Space ◽  
Fast Decay ◽  
Early Solar System ◽  
The Past ◽  
Solar System Bodies ◽  
Main Asteroid Belt

ABSTRACT In two recent papers published in MNRAS, Namouni and Morais claimed evidence for the interstellar origin of some small Solar system bodies, including: (i) objects in retrograde co-orbital motion with the giant planets and (ii) the highly inclined Centaurs. Here, we discuss the flaws of those papers that invalidate the authors’ conclusions. Numerical simulations backwards in time are not representative of the past evolution of real bodies. Instead, these simulations are only useful as a means to quantify the short dynamical lifetime of the considered bodies and the fast decay of their population. In light of this fast decay, if the observed bodies were the survivors of populations of objects captured from interstellar space in the early Solar system, these populations should have been implausibly large (e.g. about 10 times the current main asteroid belt population for the retrograde co-orbital of Jupiter). More likely, the observed objects are just transient members of a population that is maintained in quasi-steady state by a continuous flux of objects from some parent reservoir in the distant Solar system. We identify in the Halley-type comets and the Oort cloud the most likely sources of retrograde co-orbitals and highly inclined Centaurs.

scholarly journals Planetary Trojans – the main source of short period comets?

2010 ◽  
Vol 9 (4) ◽  
pp. 227-234 ◽  
Author(s):  
J. Horner ◽  
P. S. Lykawka
Keyword(s):  
Solar System ◽  
Short Review ◽  
Oort Cloud ◽  
Asteroid Belt ◽  
Exoplanetary Systems ◽  
Short Period ◽  
Proximate Source ◽  
Different Origins ◽  
Near Earth Asteroids ◽  
The Impact

AbstractOne of the key considerations when assessing the potential habitability of telluric worlds will be that of the impact regime experienced by the planet. In this work, we present a short review of our understanding of the impact regime experienced by the terrestrial planets within our own Solar system, describing the three populations of potentially hazardous objects which move on orbits that take them through the inner Solar system. Of these populations, the origins of two (the Near-Earth Asteroids and the Long-Period Comets) are well understood, with members originating in the Asteroid belt and Oort cloud, respectively. By contrast, the source of the third population, the Short-Period Comets, is still under debate. The proximate source of these objects is the Centaurs, a population of dynamically unstable objects that pass perihelion (closest approach to the Sun) between the orbits of Jupiter and Neptune. However, a variety of different origins have been suggested for the Centaur population. Here, we present evidence that at least a significant fraction of the Centaur population can be sourced from the planetary Trojan clouds, stable reservoirs of objects moving in 1:1 mean-motion resonance with the giant planets (primarily Jupiter and Neptune). Focussing on simulations of the Neptunian Trojan population, we show that an ongoing flux of objects should be leaving that region to move on orbits within the Centaur population. With conservative estimates of the flux from the Neptunian Trojan clouds, we show that their contribution to that population could be of order ~3%, while more realistic estimates suggest that the Neptune Trojans could even be the main source of fresh Centaurs. We suggest that further observational work is needed to constrain the contribution made by the Neptune Trojans to the ongoing flux of material to the inner Solar system, and believe that future studies of the habitability of exoplanetary systems should take care not to neglect the contribution of resonant objects (such as planetary Trojans) to the impact flux that could be experienced by potentially habitable worlds.

scholarly journals Dynamical Evolution of the Early Solar System

2018 ◽  
Vol 56 (1) ◽  
pp. 137-174 ◽  
Author(s):  
David Nesvorný
Keyword(s):  
Solar System ◽  
Kuiper Belt ◽  
Dynamical Evolution ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Dynamical Instability ◽  
Orbital Energy ◽  
Interstellar Space ◽  
Early Solar System ◽  
Planetary Migration

Several properties of the Solar System, including the wide radial spacing of the giant planets, can be explained if planets radially migrated by exchanging orbital energy and momentum with outer disk planetesimals. Neptune's planetesimal-driven migration, in particular, has a strong advocate in the dynamical structure of the Kuiper belt. A dynamical instability is thought to have occurred during the early stages with Jupiter having close encounters with a Neptune-class planet. As a result of the encounters, Jupiter acquired its current orbital eccentricity and jumped inward by a fraction of an astronomical unit, as required for the survival of the terrestrial planets and from asteroid belt constraints. Planetary encounters also contributed to capture of Jupiter Trojans and irregular satellites of the giant planets. Here we discuss the dynamical evolution of the early Solar System with an eye to determining how models of planetary migration/instability can be constrained from its present architecture. Specifically, we review arguments suggesting that the Solar System may have originally contained a third ice giant on a resonant orbit between Saturn and Uranus. This hypothesized planet was presumably ejected into interstellar space during the instability. The Kuiper belt kernel and other dynamical structures in the trans-Neptunian region may provide evidence for the ejected planet. We favor the early version of the instability where Neptune migrated into the outer planetesimal disk within a few tens of millions of years after the dispersal of the protosolar nebula. If so, the planetary migration/instability was not the cause of the Late Heavy Bombardment. Mercury's orbit may have been excited during the instability.

scholarly journals The Grand Tack model: a critical review

2014 ◽  
Vol 9 (S310) ◽  
pp. 194-203 ◽  
Author(s):  
Sean N. Raymond ◽  
Alessandro Morbidelli
Keyword(s):  
Solar System ◽  
Building Blocks ◽  
Protoplanetary Disk ◽  
Giant Planets ◽  
Asteroid Belt ◽  
Terrestrial Planets ◽  
Saturn’S Satellites ◽  
Internal Inconsistency ◽  
Solar System Bodies ◽  
Gas Accretion

AbstractThe “Grand Tack” model proposes that the inner Solar System was sculpted by the giant planets' orbital migration in the gaseous protoplanetary disk. Jupiter first migrated inward then Jupiter and Saturn migrated back outward together. If Jupiter's turnaround or “tack” point was at ~ 1.5 AU the inner disk of terrestrial building blocks would have been truncated at ~ 1 AU, naturally producing the terrestrial planets' masses and spacing. During the gas giants' migration the asteroid belt is severely depleted but repopulated by distinct planetesimal reservoirs that can be associated with the present-day S and C types. The giant planets' orbits are consistent with the later evolution of the outer Solar System.Here we confront common criticisms of the Grand Tack model. We show that some uncertainties remain regarding the Tack mechanism itself; the most critical unknown is the timing and rate of gas accretion onto Saturn and Jupiter. Current isotopic and compositional measurements of Solar System bodies – including the D/H ratios of Saturn's satellites – do not refute the model. We discuss how alternate models for the formation of the terrestrial planets each suffer from an internal inconsistency and/or place a strong and very specific requirement on the properties of the protoplanetary disk.We conclude that the Grand Tack model remains viable and consistent with our current understanding of planet formation. Nonetheless, we encourage additional tests of the Grand Tack as well as the construction of alternate models.

scholarly journals New Results on the Composition of the Outer Planets and Titan

2005 ◽  
Vol 13 ◽  
pp. 891-893
Author(s):  
Thierry Fouchet
Keyword(s):  
Solar System ◽  
Atmospheric Chemistry ◽  
Recent Progress ◽  
Giant Planets ◽  
Atmospheric Composition ◽  
Solar System Formation ◽  
Outer Planets ◽  
System Formation ◽  
The Impact

AbstractIn this brief summary, I present recent progress on our knowledge of the Giant Planets and Titan atmospheric composition, as well as the impact of this progress on our understanding of Solar System formation, and atmospheric chemistry.

scholarly journals Erosive Hit-and-Run Impact Events: Debris Unbound

2015 ◽  
Vol 10 (S318) ◽  
pp. 9-15
Author(s):  
Gal Sarid ◽  
Sarah T. Stewart ◽  
Zoë M. Leinhardt
Keyword(s):  
Solar System ◽  
Asteroid Belt ◽  
Mass Composition ◽  
Residual Velocity ◽  
Processed Material ◽  
Planetary Bodies ◽  
Hit And Run ◽  
Main Asteroid Belt ◽  
Impact Events

AbstractErosive collisions among planetary embryos in the inner solar system can lead to multiple remnant bodies, varied in mass, composition and residual velocity. Some of the smaller, unbound debris may become available to seed the main asteroid belt. The makeup of these collisionally produced bodies is different from the canonical chondritic composition, in terms of rock/iron ratio and may contain further shock-processed material. Having some of the material in the asteroid belt owe its origin from collisions of larger planetary bodies may help in explaining some of the diversity and oddities in composition of different asteroid groups.

scholarly journals Masses of asteroids and total mass of the main asteroid belt

2015 ◽  
Vol 10 (S318) ◽  
pp. 212-217
Author(s):  
E. V. Pitjeva ◽  
N. P. Pitjev
Keyword(s):  
Total Mass ◽  
Radar Data ◽  
Asteroid Belt ◽  
Two Dimensional ◽  
Binary Asteroids ◽  
One Dimensional ◽  
Main Asteroid Belt ◽  
The Individual ◽  
The Masses ◽  
Academy Of Sciences

AbstractAn estimation of the mass of the main asteroid belt was made on the basis of the new version of EPM2014 ephemerides of the Institute of Applied Astronomy of Russian Academy of Sciences using about 800000 positional observations of planets and spacecraft. We obtained the individual estimations of masses of large asteroids from radar data, as well as estimates of the masses of asteroids by using known diameters and estimated average densities for the three taxonomic types (C, S, M), and used the known mass values of binary asteroids and asteroids to which spacecraft approached. A two-dimensional homogeneous annulus with dimensions corresponding observed width of the main asteroid belt (2.06 au and 3.27 au) was used instead of a previous massive one-dimensional ring for modeling total perturbations from small asteroids. The obtained value of the total mass of the main asteroid belt is (12.25 ± 0.19)10−10M⊙.

scholarly journals Jupiter – friend or foe? II: the Centaurs

2008 ◽  
Vol 8 (2) ◽  
pp. 75-80 ◽  
Author(s):  
J. Horner ◽  
B.W. Jones
Keyword(s):  
Solar System ◽  
Kuiper Belt ◽  
Giant Planet ◽  
Mass Extinctions ◽  
The Earth ◽  
Impact Rate ◽  
Short Period ◽  
Impact Risk ◽  
Life On Earth ◽  
The Impact

AbstractIt has long been assumed that the planet Jupiter acts as a giant shield, significantly lowering the impact rate of minor bodies upon the Earth, and thus enabling the development and evolution of life in a collisional environment which is not overly hostile. In other words, it is thought that, thanks to Jupiter, mass extinctions have been sufficiently infrequent that the biosphere has been able to diversify and prosper. However, in the past, little work has been carried out to examine the validity of this idea. In the second of a series of papers, we examine the degree to which the impact risk resulting from objects on Centaur-like orbits is affected by the presence of a giant planet, in an attempt to fully understand the impact regime under which life on Earth has developed. The Centaurs are a population of ice-rich bodies which move on dynamically unstable orbits in the outer Solar system. The largest Centaurs known are several hundred kilometres in diameter, and it is certain that a great number of kilometre or sub-kilometre sized Centaurs still await discovery. These objects move on orbits which bring them closer to the Sun than Neptune, although they remain beyond the orbit of Jupiter at all times, and have their origins in the vast reservoir of debris known as the Edgeworth–Kuiper belt that extends beyond Neptune. Over time, the giant planets perturb the Centaurs, sending a significant fraction into the inner Solar System where they become visible as short-period comets. In this work, we obtain results which show that the presence of a giant planet can act to significantly change the impact rate of short-period comets on the Earth, and that such planets often actually increase the impact flux greatly over that which would be expected were a giant planet not present.

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