Dust condensation in evolving discs and the composition of planetary building blocks

ABSTRACT Partial condensation of dust from the Solar nebula is likely responsible for the diverse chemical compositions of chondrites and rocky planets/planetesimals in the inner Solar system. We present a forward physical–chemical model of a protoplanetary disc to predict the chemical compositions of planetary building blocks that may form from such a disc. Our model includes the physical evolution of the disc and the condensation, partial advection, and decoupling of the dust within it. The chemical composition of the condensate changes with time and radius. We compare the results of two dust condensation models: one where an element condenses when the mid-plane temperature in the disc is lower than the 50 per cent condensation temperature ($\rm T_{50}$) of that element and the other where the condensation of the dust is calculated by a Gibbs free energy minimization technique assuming chemical equilibrium at local disc temperature and pressure. The results of two models are generally consistent with some systematic differences of ∼10 per cent depending upon the radial distance and an element’s condensation temperature. Both models predict compositions similar to CM, CO, and CV chondrites provided that the decoupling time-scale of the dust is of the order of the evolution time-scale of the disc or longer. If the decoupling time-scale is too short, the composition deviates significantly from the measured values. These models may contribute to our understanding of the chemical compositions of chondrites, and ultimately the terrestrial planets in the Solar system, and may constrain the potential chemical compositions of rocky exoplanets.

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Nebular condensation of different stellar compositions and its influence on planetary chemistry

10.5194/epsc2020-874 ◽

2020 ◽

Author(s):

Haiyang Wang ◽

Paolo Sossi ◽

Sascha Quanz

Keyword(s):

Solar System ◽

Gas Phase ◽

Building Blocks ◽

Condensation Process ◽

Condensation Temperature ◽

Energy Minimisation ◽

Extrasolar Systems ◽

Solar Composition ◽

High Metal ◽

General Order

The volatility of an element is defined by its 50% condensation temperature (Tc50) from a canonical nebular gas of Solar composition at 10-4 bar [1, 2]. However, the variability in metallicity and metal/oxygen ratios of extrasolar systems inferred from the spectroscopic measurements of their parent stars [3, 4] implies that the identity, abundance and sequence of condensation may deviate from that of our solar system. As such, planets formed at similar heliocentric distances may be expected to have distinct compositions from those of the terrestrial planets in our solar system. Here we investigate the degree to which nebular composition influences the condensation process by taking nine sets of stellar compositions with variable metallicities that span the range from -0.4 to +0.4 dex and performing Gibbs free energy minimisation calculations with FactSage, including treatment of mineral solid-solutions, &#160;over the temperature range 1723 K to 473 K. &#160;We find that, although the general order of condensation is similar, absolute values of Tc50 are shifted to higher temperatures at higher dex, where Tc50(S), in particular, increases relative to those of other elements. Condensing nebulae with high metallicities (and also high metal/oxygen ratios) also exhibit the following features: (i) the appearance of reduced assemblages (e.g. CaS oldhamite, forsterite-rich olivine and graphite) in the condensates, (ii) increased fractions of oxygen (relative to its total abundance) locked in the silicate condensates, and (iii) lower fO2 in the gas phase. As a result, these characteristics will lead to significant differences in the chemistry of planetary building blocks, which are then accreted to form telluric planetary bodies. &#160; References [1] Lodders 2003. ApJ 591:1220-1247.&#160; [2] Wood, B. J., Smythe, D. J., & Harrison, T. 2019. Ame. Miner. 104:844-856. [3] Buder, S., Asplund, M., Duong, L. et al. 2018. MNRAS 478:4513:4552. [4] Delgado Mena, E., Moya, A., Adibekyan, V., et al. 2019. A&A 624:A78.

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Cosmic Chemistry

From Dust to Life ◽

10.23943/princeton/9780691175706.003.0006 ◽

2017 ◽

Author(s):

John Chambers ◽

Jacqueline Mitton

Keyword(s):

Solar System ◽

Chemical Elements ◽

Building Blocks ◽

Big Bang ◽

Rich Variety ◽

Gold Silver ◽

The Rich ◽

Rocky Planets ◽

The Big Bang ◽

The Universe

This chapter analyzes how humans owe their existence to the rich variety of chemical elements that exist in the universe. The solar system contains hydrogen to power the Sun; iron and silicon to build rocky planets; and carbon, nitrogen, and oxygen to form the building blocks of life. Almost 100 elements occur naturally in the solar system in varying amounts. Some, like hydrogen, oxygen, and iron, are abundant everywhere. Others, like gold, silver, and uranium, are much less common. The mixture of elements has remained almost constant since the solar system formed, apart from changes deep in the Sun's interior. The chapter shows how the composition of the solar system was shaped by events elsewhere in the universe dating back to the Big Bang itself.

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Laboratory and in-situ analysis of comet dust

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100102122 ◽

1988 ◽

Vol 46 ◽

pp. 8-9

Author(s):

D.E. Brownlee ◽

A.L. Albee

Keyword(s):

Electron Microscopy ◽

Solar System ◽

Laboratory Study ◽

Isotopic Analysis ◽

Building Blocks ◽

Sem Analysis ◽

Early Solar System ◽

Cometary Material ◽

Comet Dust

Comets are primitive, kilometer-sized bodies that formed in the outer regions of the solar system. Composed of ice and dust, comets are generally believed to be relic building blocks of the outer solar system that have been preserved at cryogenic temperatures since the formation of the Sun and planets. The analysis of cometary material is particularly important because the properties of cometary material provide direct information on the processes and environments that formed and influenced solid matter both in the early solar system and in the interstellar environments that preceded it.The first direct analyses of proven comet dust were made during the Soviet and European spacecraft encounters with Comet Halley in 1986. These missions carried time-of-flight mass spectrometers that measured mass spectra of individual micron and smaller particles. The Halley measurements were semi-quantitative but they showed that comet dust is a complex fine-grained mixture of silicates and organic material. A full understanding of comet dust will require detailed morphological, mineralogical, elemental and isotopic analysis at the finest possible scale. Electron microscopy and related microbeam techniques will play key roles in the analysis. The present and future of electron microscopy of comet samples involves laboratory study of micrometeorites collected in the stratosphere, in-situ SEM analysis of particles collected at a comet and laboratory study of samples collected from a comet and returned to the Earth for detailed study.

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Preface: Evolution of the early solar system: Presolar cosmochemical fingerprints and the formation of watery rocky planets

GEOCHEMICAL JOURNAL ◽

10.2343/geochemj.2.0416 ◽

2016 ◽

Vol 50 (1) ◽

pp. 1-2 ◽

Cited By ~ 1

Author(s):

Tomohiro Usui ◽

Audrey Bouvier ◽

Justin I. Simon ◽

Noriko Kita

Keyword(s):

Solar System ◽

Early Solar System ◽

Rocky Planets

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The Grand Tack model: a critical review

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314008254 ◽

2014 ◽

Vol 9 (S310) ◽

pp. 194-203 ◽

Cited By ~ 12

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.

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The Formation of Mars: Building Blocks and Accretion Time Scale

Quantifying the Martian Geochemical Reservoirs - Space Sciences Series of ISSI ◽

10.1007/978-1-4614-7774-7_3 ◽

2012 ◽

pp. 11-25

Author(s):

Ramon Brasser

Keyword(s):

Time Scale ◽

Building Blocks

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Features of the geochemistry of the Moon and the Earth, determined by the mechanism of formation of the Earth – Moon system (report at the 81st international meteorite conference, Moscow, july 2018)

Геохимия ◽

10.31857/s0016-7525648762-776 ◽

2019 ◽

Vol 64 (8) ◽

pp. 762-776

Author(s):

E. M. Galimov

Keyword(s):

Solar System ◽

Volatile Components ◽

Kinetic Regime ◽

The Moon ◽

Mechanism Of Formation ◽

Planetary Body ◽

Moon System ◽

The Earth ◽

Reversible Nature ◽

Dust Condensation

This article discusses some features of geochemistry of the Earth and the Moon, which manifests the specificity of the mechanism of their formation by fragmentation of protoplanetary gas-dust condensation (Galimov & Krivtsov, 2012). The principal difference between this model and other hypotheses of the Earth-Moon system formation, including the megaimpact hypothesis, is that it assumes the existence of a long stage of the dispersed state of matter, starting with the formation of protoplanetary gas-dust condensation, its compression and fragmentation and ending with the final accretion to the formed high-temperature embryos of the Earth and the Moon. The presence of the dispersed state allows a certain way to interpret the observed properties of the Earth-Moon system. Partial evaporation of solid particles due to adiabatic heating of the compressing condensation leads to the loss of volatiles including FeO. Computer simulations show that the final accretion is mainly performed on a larger fragment (the Earth’s embryo) and only slightly increases the mass of the smaller fragment (the Moon embryo).This explains the relative depletion of the Moon in iron and volatile and the increased concentration of refractory components compared to the Earth. The reversible nature of evaporation into the dispersed space, in contrast to the kinetic regime, and the removal of volatiles in the hydrodynamic flow beyond the gas-dust condensation determines the loss of volatiles without the effect of isotopes fractionation. The reversible nature of volatile evaporation also provides, in contrast to the kinetic regime, the preservation of part of the high-volatile components, such as water, in the planetary body, including the Moon. It follows from the essence of the model that at least a significant part of the Earth’s core is formed not by segregation of iron in the silicate-metal melt, but by evaporation and reduction of FeO in a dispersed medium, followed by deposition of clusters of elemental iron to the center of mass. This mechanism of formation of the core explains the observed excess of siderophilic elements in the Earth’s mantle. It also provides a plausible explanation for the observed character of iron isotopes fractionation (in terms of δ57Fe‰) on Earth and on the Moon. It solves the problem of the formation of iron core from initially oxide (FeO) form. The dispersed state of the substance during the period of accretion suggests that the loss of volatiles occurred during the time of accretion. Using the fact that isotopic systems: U–Pb, Rb–Sr, 129J–129Xe, 244Pu–136Xe, contain volatile components, it is possible to estimate the chronology of events in the evolution of the protoplanetary state. As a result, agreed estimates of the time of fragmentation of the primary protoplanetary condensation and formation of the embryos of the Earth and the Moon are obtained: from 10 to 40 million years, and the time of completion of the earth’s accretion and its birth as a planetary body: 110 – 130 million years after the emergence of the solar system. The presented interpretation is consistent with the fact that solid minerals on the Moon have already appeared at least 60 million years after the birth of the solar system (Barboni et al., 2017), and the metal core in the Earth and in the Moon could not have formed before 50 million years from the start of the solar system, as follows from the analysis of the Hf-W system (Kleine et al., 2009). It is shown that the hypothesis of megaimpact does not satisfy many constraints and does not create a basis for the explanation of the geochemistry of the Earth and the Moon.

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Tracing the Origins of the Ice Giants through Noble Gas Isotopic Composition

10.5194/egusphere-egu21-7798 ◽

2021 ◽

Author(s):

Kathleen Mandt ◽

Olivier Mousis ◽

Jonathan Lunine ◽

Bernard Marty ◽

Thomas Smith ◽

...

Keyword(s):

Solar System ◽

Isotopic Composition ◽

Heavy Element ◽

Noble Gas ◽

Giant Planet ◽

Isotope Ratios ◽

Building Blocks ◽

Giant Planets ◽

Element Abundances ◽

Current State

The current composition of giant planet atmospheres provides information on how such planets formed, and on the origin of the solid building blocks that contributed to their formation. Noble gas abundances and their isotope ratios are among the most valuable pieces of evidence for tracing the origin of the materials from which the giant planets formed. In this review we first outline the current state of knowledge for heavy element abundances in the giant planets and explain what is currently understood about the reservoirs of icy building blocks that could have contributed to the formation of the Ice Giants. We then outline how noble gas isotope ratios have provided details on the original sources of noble gases in various materials throughout the solar system. We follow this with a discussion on how noble gases are trapped in ice and rock that later became the building blocks for the giant planets and how the heavy element abundances could have been locally enriched in the protosolar nebula. We then provide a review of the current state of knowledge of noble gas abundances and isotope ratios in various solar system reservoirs, and discuss measurements needed to understand the origin of the ice giants. Finally, we outline how formation and interior evolution will influence the noble gas abundances and isotope ratios observed in the ice giants today. Measurements that a future atmospheric probe will need to make include (1) the 3He/4He isotope ratio to help constrain the protosolar D/H and 3He/4He; (2) the 20Ne/22Ne and 21Ne/22Ne to separate primordial noble gas reservoirs similar to the approach used in studying meteorites; (3) the Kr/Ar and Xe/Ar to determine if the building blocks were Jupiter-like or similar to 67P/C-G and Chondrites; (4) the krypton isotope ratios for the first giant planet observations of these isotopes; and (5) the xenon isotopes for comparison with the wide range of values represented by solar system reservoirs.Mandt, K. E., Mousis, O., Lunine, J., Marty, B., Smith, T., Luspay-Kuti, A., & Aguichine, A. (2020). Tracing the origins of the ice giants through noble gas isotopic composition. Space Science Reviews, 216(5), 1-37.

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The Importance of Phobos Sample Return for Understanding the Mars-Moon System

Space Science Reviews ◽

10.1007/s11214-020-00668-9 ◽

2020 ◽

Vol 216 (4) ◽

Cited By ~ 3

Author(s):

Tomohiro Usui ◽

Ken-ichi Bajo ◽

Wataru Fujiya ◽

Yoshihiro Furukawa ◽

Mizuho Koike ◽

...

Keyword(s):

Solar System ◽

Sampling Site ◽

Bulk Composition ◽

Building Blocks ◽

Interplanetary Dust ◽

Radiometric Dating ◽

Dust Particles ◽

Interplanetary Dust Particles ◽

Sample Return ◽

On The Road

Abstract Phobos and Deimos occupy unique positions both scientifically and programmatically on the road to the exploration of the solar system. Japan Aerospace Exploration Agency (JAXA) plans a Phobos sample return mission (MMX: Martian Moons eXploration). The MMX spacecraft is scheduled to be launched in 2024, orbit both Phobos and Deimos (multiple flybys), and retrieve and return >10 g of Phobos regolith back to Earth in 2029. The Phobos regolith represents a mixture of endogenous Phobos building blocks and exogenous materials that contain solar system projectiles (e.g., interplanetary dust particles and coarser materials) and ejecta from Mars and Deimos. Under the condition that the representativeness of the sampling site(s) is guaranteed by remote sensing observations in the geologic context of Phobos, laboratory analysis (e.g., mineralogy, bulk composition, O-Cr-Ti isotopic systematics, and radiometric dating) of the returned sample will provide crucial information about the moon’s origin: capture of an asteroid or in-situ formation by a giant impact. If Phobos proves to be a captured object, isotopic compositions of volatile elements (e.g., D/H, 13C/12C, 15N/14N) in inorganic and organic materials will shed light on both organic-mineral-water/ice interactions in a primitive rocky body originally formed in the outer solar system and the delivery process of water and organics into the inner rocky planets.

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Solar System chaos and the Paleocene–Eocene boundary age constrained by geology and astronomy

Science ◽

10.1126/science.aax0612 ◽

2019 ◽

Vol 365 (6456) ◽

pp. 926-929 ◽

Cited By ~ 21

Author(s):

Richard E. Zeebe ◽

Lucas J. Lourens

Keyword(s):

Solar System ◽

Time Scale ◽

Dynamical Evolution ◽

Resonance Transition ◽

Fundamental Frequencies ◽

Thermal Maximum ◽

Astronomical Time ◽

Geologic Data

Astronomical calculations reveal the Solar System’s dynamical evolution, including its chaoticity, and represent the backbone of cyclostratigraphy and astrochronology. An absolute, fully calibrated astronomical time scale has hitherto been hampered beyond ~50 million years before the present (Ma) because orbital calculations disagree before that age. Here, we present geologic data and a new astronomical solution (ZB18a) showing exceptional agreement from ~58 to 53 Ma. We provide a new absolute astrochronology up to 58 Ma and a new Paleocene–Eocene boundary age (56.01 ± 0.05 Ma). We show that the Paleocene–Eocene Thermal Maximum (PETM) onset occurred near a 405-thousand-year (kyr) eccentricity maximum, suggesting an orbital trigger. We also provide an independent PETM duration (170 ± 30 kyr) from onset to recovery inflection. Our astronomical solution requires a chaotic resonance transition at ~50 Ma in the Solar System’s fundamental frequencies.

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