Solar System Physics for Exoplanet Research Horner, J.; Kane, S. R.; Marshall, J. P. ...
Publications of the Astronomical Society of the Pacific,
10/2020, Letnik:
132, Številka:
1016
Journal Article
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Over the past three decades, we have witnessed one of the great revolutions in our understanding of the cosmos-the dawn of the Exoplanet Era. Where once we knew of just one planetary system (the ...solar system), we now know of thousands, with new systems being announced on a weekly basis. Of the thousands of planetary systems we have found to date, however, there is only one that we can study up-close and personal-the solar system. In this review, we describe our current understanding of the solar system for the exoplanetary science community-with a focus on the processes thought to have shaped the system we see today. In section one, we introduce the solar system as a single well studied example of the many planetary systems now observed. In section two, we describe the solar system's small body populations as we know them today-from the two hundred and five known planetary satellites to the various populations of small bodies that serve as a reminder of the system's formation and early evolution. In section three, we consider our current knowledge of the solar system's planets, as physical bodies. In section four we discuss the research that has been carried out into the solar system's formation and evolution, with a focus on the information gleaned as a result of detailed studies of the system's small body populations. In section five, we discuss our current knowledge of planetary systems beyond our own-both in terms of the planets they host, and in terms of the debris that we observe orbiting their host stars. As we learn ever more about the diversity and ubiquity of other planetary systems, our solar system will remain the key touchstone that facilitates our understanding and modeling of those newly found systems, and we finish section five with a discussion of the future surveys that will further expand that knowledge.
Abstract
Mass-independent isotopic anomalies of carbonaceous and noncarbonaceous meteorites show a clear dichotomy suggesting an efficient separation of the inner and outer solar system. Observations ...show that ring-like structures in the distribution of millimeter-sized pebbles in protoplanetary disks are common. These structures are often associated with drifting pebbles being trapped by local pressure maxima in the gas disk. Similar structures may also have existed in the Sun’s natal disk, which could naturally explain the meteorite/planetary isotopic dichotomy. Here, we test the effects of a strong pressure bump in the outer disk (e.g., ∼5 au) on the formation of the inner solar system. We model dust coagulation and evolution, planetesimal formation, as well as embryo growth via planetesimal and pebble accretion. Our results show that terrestrial embryos formed via planetesimal accretion rather than pebble accretion. In our model, the radial drift of pebbles fosters planetesimal formation. However, once a pressure bump forms, pebbles in the inner disk are lost via drift before they can be efficiently accreted by embryos growing at ⪆1 au. Embryos inside ∼0.5–1.0 au grow relatively faster and can accrete pebbles more efficiently. However, these same embryos grow to larger masses so they should migrate inwards substantially, which is inconsistent with the current solar system. Therefore, terrestrial planets most likely accreted from giant impacts of Moon to roughly Mars-mass planetary embryos formed around ⪆1.0 au. Finally, our simulations produce a steep radial mass distribution of planetesimals in the terrestrial region, which is qualitatively aligned with formation models suggesting that the asteroid belt was born low mass.
We use published models of the early solar system evolution with a slow, long-range and grainy migration of Neptune to predict the orbital element distributions and the number of modern-day Centaurs. ...The model distributions are biased by the Outer Solar System Origins Survey (OSSOS) simulator and compared with the OSSOS Centaur detections. We find an excellent match to the observed orbital distribution, including the wide range of orbital inclinations which was the most troublesome characteristic to fit in previous models. A dynamical model, in which the original population of outer disk planetesimals was calibrated from Jupiter trojans, is used to predict that OSSOS should detect 11 4 Centaurs with semimajor axes of a < 30 au, perihelion distances of q > 7.5 au, and diameter of D > 10 km (absolute magnitude Hr < 13.7 for a 6% albedo). This is consistent with 15 actual OSSOS Centaur detections with Hr < 13.7. The population of Centaurs is estimated to be 21,000 8000 for D > 10 km. The inner scattered disk at 50 < a < 200 au should contain (2.0 0.8) × 107 D > 10 km bodies and the Oort cloud should contain (5.0 1.9) × 108 D > 10 km comets. Population estimates for different diameter cutoffs can be obtained from the size distribution of Jupiter trojans (N(>D) ∝ D−2.1 for 5 < D < 100 km). We discuss model predictions for the Large Synoptic Survey Telescope observations of Centaurs.
Origin and Evolution of Short-period Comets Nesvorný, David; Vokrouhlický, David; Dones, Luke ...
Astrophysical journal/The Astrophysical journal,
08/2017, Letnik:
845, Številka:
1
Journal Article
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Comets are icy objects that orbitally evolve from the trans-Neptunian region into the inner solar system, where they are heated by solar radiation and become active due to the sublimation of water ...ice. Here we perform simulations in which cometary reservoirs are formed in the early solar system and evolved over 4.5 Gyr. The gravitational effects of Planet 9 (P9) are included in some simulations. Different models are considered for comets to be active, including a simple assumption that comets remain active for perihelion passages with perihelion distance . The orbital distribution and number of active comets produced in our model is compared to observations. The orbital distribution of ecliptic comets (ECs) is well reproduced in models with and without P9. With P9, the inclination distribution of model ECs is wider than the observed one. We find that the known Halley-type comets (HTCs) have a nearly isotropic inclination distribution. The HTCs appear to be an extension of the population of returning Oort-cloud comets (OCCs) to shorter orbital periods. The inclination distribution of model HTCs becomes broader with increasing , but the existing data are not good enough to constrain from orbital fits. is required to obtain a steady-state population of large active HTCs that is consistent with observations. To fit the ratio of the returning-to-new OCCs, by contrast, our model implies that , possibly because the detected long-period comets are smaller and much easier to disrupt than observed HTCs.
Abstract
The inner solar system possesses a unique orbital structure in which there are no planets inside the Mercury orbit and the mass is concentrated around the Venus and Earth orbits. The origins ...of these features still remain unclear. We propose a novel concept that the building blocks of the inner solar system formed at the dead-zone inner edge in the early phase of the protosolar disk evolution, where the disk is effectively heated by the disk accretion. First, we compute the dust evolution in a gas disk with a dead zone and obtain the spatial distribution of rocky planetesimals. The disk is allowed to evolve both by a viscous diffusion and magnetically driven winds. We find that the rocky planetesimals are formed in concentrations around ∼1 au with a total mass comparable to the mass of the current inner solar system in the early phase of the disk evolution within ≲0.1 Myr. Based on the planetesimal distribution and the gas-disk structure, we subsequently perform
N
-body simulations of protoplanets to investigate the dynamical configuration of the planetary system. We find that the protoplanets can grow into planets without significant orbital migration because of the rapid clearing of the inner disk by the magnetically driven disk winds. Our model can explain the origins of the orbital structure of the inner solar system. Several other features such as the rocky composition can also be explained by the early formation of rocky planetesimals.
The origin of inner Solar System water Alexander, Conel M. O'D.
Philosophical transactions - Royal Society. Mathematical, Physical and engineering sciences/Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences,
05/2017, Letnik:
375, Številka:
2094
Journal Article
Recenzirano
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Of the potential volatile sources for the terrestrial planets, the CI and CM carbonaceous chondrites are closest to the planets' bulk H and N isotopic compositions. For the Earth, the addition of ...approximately 2-4 wt% of CI/CM material to a volatile-depleted proto-Earth can explain the abundances of many of the most volatile elements, although some solar-like material is also required. Two dynamical models of terrestrial planet formation predict that the carbonaceous chondrites formed either in the asteroid belt ('classical' model) or in the outer Solar System (5-15 AU in the Grand Tack model). To test these models, at present the H isotopes of water are the most promising indicators of formation location because they should have become increasingly D-rich with distance from the Sun. The estimated initial H isotopic compositions of water accreted by the CI, CM, CR and Tagish Lake carbonaceous chondrites were much more D-poor than measured outer Solar System objects. A similar pattern is seen for N isotopes. The D-poor compositions reflect incomplete re-equilibration with H2 in the inner Solar System, which is also consistent with the O isotopes of chondritic water. On balance, it seems that the carbonaceous chondrites and their water did not form very far out in the disc, almost certainly not beyond the orbit of Saturn when its moons formed (approx. 3-7 AU in the Grand Tack model) and possibly close to where they are found today.
This article is part of the themed issue ‘The origin, history and role of water in the evolution of the inner Solar System’.
Containing only a few percentages of the mass of the moon, the current asteroid belt is around three to four orders of magnitude smaller than its primordial mass inferred from disk models. Yet ...dynamical studies have shown that the asteroid belt could not have been depleted by more than about an order of magnitude over the past ∼4 Gyr. The remainder of the mass loss must have taken place during an earlier phase of the solar system's evolution. An orbital instability in the outer solar system occurring during the process of terrestrial planet formation can reproduce the broad characteristics of the inner solar system. Here, we test the viability of this model within the constraints of the main belt's low present-day mass and orbital structure. Although previous studies modeled asteroids as massless test particles because of limited computing power, our work uses graphics processing unit acceleration to model a fully self-gravitating asteroid belt. We find that depletion in the main belt is related to the giant planets' exact evolution within the orbital instability. Simulations that produce the closest matches to the giant planets' current orbits deplete the main belt by two to three orders of magnitude. These simulated asteroid belts are also good matches to the actual asteroid belt in terms of their radial mixing and broad orbital structure.
The age of Jupiter, the largest planet in our Solar System, is still unknown. Gas-giant planet formation likely involved the growth of large solid cores, followed by the accumulation of gas onto ...these cores. Thus, the gas-giant cores must have formed before dissipation of the solar nebula, which likely occurred within less than 10 My after Solar System formation. Although such rapid accretion of the gas-giant cores has successfully been modeled, until now it has not been possible to date their formation. Here, using molybdenum and tungsten isotope measurements on iron meteorites, we demonstrate that meteorites derive from two genetically distinct nebular reservoirs that coexisted and remained spatially separated between ∼1 My and ∼3–4 My after Solar System formation. The most plausible mechanism for this efficient separation is the formation of Jupiter, opening a gap in the disk and preventing the exchange of material between the two reservoirs. As such, our results indicate that Jupiter’s core grew to ∼20 Earth masses within <1 My, followed by a more protracted growth to ∼50 Earth masses until at least ∼3–4 My after Solar System formation. Thus, Jupiter is the oldest planet of the Solar System, and its solid core formed well before the solar nebula gas dissipated, consistent with the core accretion model for giant planet formation.
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