Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

MacPherson, G. J.

doi:10.1016/b978-0-08-095975-7.00105-4

Cited by 104 publications

(101 citation statements)

References 227 publications

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“…The beginning of the solar systemʼs formation is often defined as the time that the first solids condensed in the Sunʼs protoplanetary disk as it cooled. The oldest known substances are calcium aluminum inclusions (CAIs) found in carbonaceous chondrite meteorites, and radiometric dating places their origins at ∼4.567 billion years ago (Connelly et al 2012;MacPherson 2014).…”

Section: Chronologymentioning

confidence: 99%

“…Despite these limitations, numerical N-body simulations that assumed perfect accretion have been successful at reproducing the broad characteristics of the terrestrial planets in our solar system (Wetherill 1994;Chambers 2001;Quintana et al 2002;Raymond et al 2004Raymond et al , 2006Raymond et al , 2009O'Brien et al 2006;Quintana & Lissauer 2006, 2014. These results were all based on a small (up to a dozen) number of realizations performed for each set of initial conditions.…”

Section: Introductionmentioning

confidence: 99%

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The Frequency of Giant Impacts on Earth-Like Worlds

Quintana

Barclay

Borucki

et al. 2016

ApJ

142

132

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The late stages of terrestrial planet formation are dominated by giant impacts that collectively influence the growth, composition, and habitability of any planets that form. Hitherto, numerical models designed to explore these late stage collisions have been limited by assuming that all collisions lead to perfect accretion, and many of these studies lack the large number of realizations needed to account for the chaotic nature of N-body systems. We improve on these limitations by performing 280 simulations of planet formation around a Sun-like star, half of which used an N-body algorithm that has recently been modified to include fragmentation and hit-and-run (bouncing) collisions. We find that when fragmentation is included, the final planets formed are comparable in terms of mass and number; however, their collision histories differ significantly and the accretion time approximately doubles. We explored impacts onto Earth-like planets, which we parameterized in terms of their specific impact energies. Only 15 of our 164 Earth-analogs experienced an impact that was energetic enough to strip an entire atmosphere. To strip about half of an atmosphere requires energies comparable to recent models of the Moon-forming giant impact. Almost all Earth-analogs received at least one impact that met this criteria during the 2 Gyr simulations and the median was three giant impacts. The median time of the final giant impact was 43 Myr after the start of the simulations, leading us to conclude that the time-frame of the Moon-forming impact is typical among planetary systems around Sun-like stars.

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Section: Chronologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Frequency of Giant Impacts on Earth-Like Worlds

Quintana

Barclay

Borucki

et al. 2016

ApJ

142

132

View full text Add to dashboard Cite

show abstract

“…Solar-wind particles, captured by the GENESIS spacecraft (2001)(2002)(2003)(2004) (Burnett et al, 2011;Burnett, 2013), provided new interesting information on the oxygen isotopic composition of the Sun (McKeegan et al, 2011). The oxygen isotopic composition of the Sun is close to that of CAIs, which is the oldest refractory rocky components with 16 O-enriched isotopic compositions (e.g., MacPherson, 2014), but is different from most of inner solar system bodies, including the Earth.…”

Section: Introductionmentioning

confidence: 95%

Hayabusa2: Scientific importance of samples returned from C-type near-Earth asteroid (162173) 1999 JU3

et al. 2014

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“…Instead, they are high-temperature primary condensates from a nebular gas. Although some CAIs have experienced complex histories of melting and evaporation (13,14), these processes are generally considered to be closed, and consequently have not resulted in the addition of large amounts of material to CAIs after they formed. Thus, these objects represent the first solids to form in the cooling solar nebula, and as such they provide primary information about the isotopic composition and degree of mixing within the CAI-forming region near the young Sun (15).…”

mentioning

confidence: 99%

Evidence for supernova injection into the solar nebula and the decoupling of r -process nucleosynthesis

Brennecka

Borg

Wadhwa

2013

Proc. Natl. Acad. Sci. U.S.A.

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The isotopic composition of our Solar System reflects the blending of materials derived from numerous past nucleosynthetic events, each characterized by a distinct isotopic signature. We show that the isotopic compositions of elements spanning a large mass range in the earliest formed solids in our Solar System, calcium-aluminum-rich inclusions (CAIs), are uniform, and yet distinct from the average Solar System composition. Relative to younger objects in the Solar System, CAIs contain positive r-process anomalies in isotopes A < 140 and negative r-process anomalies in isotopes A > 140. This fundamental difference in the isotopic character of CAIs around mass 140 necessitates (i) the existence of multiple sources for r-process nucleosynthesis and (ii) the injection of supernova material into a reservoir untapped by CAIs. A scenario of late supernova injection into the protoplanetary disk is consistent with formation of our Solar System in an active star-forming region of the galaxy.isotopic anomalies | early Solar System | H-Event | nebular disk O ur knowledge of the formation and evolution of our Solar System principally comes from (i) astrophysical observations, which provide views of other nascent stellar systems; (ii) theoretical models, which provide constraints in such systems; and (iii) direct evidence gathered from the study of meteorites that sample the earliest epoch of Solar System history. However, the details about the galactic environment in which our Solar System formed are still a matter of intense debate. Central to this effort is the study of short-lived radionuclides and nucleosynthetic anomalies found in meteorites, which constrain if, how much, and when our Solar System was injected with supernova material. This present work centers on the stable isotope signatures of the Solar System's earliest solids to unravel the earliest events that occurred after the birth of our Solar System.The elemental and isotopic composition of our Solar System reflects a mixture of materials derived from nucleosynthetic reactions in past generations of stellar environments. Isotopes of elements heavier than nickel are produced by three principal mechanisms: the p-, s-, and r-processes (1, 2). The p-process creates isotopes through photodisintegration, proton capture, and neutrino reactions in supernovae, forming neutron-deficient nuclei. The s-process occurs from slow neutron addition in asymptotic giant branch stars, in which isotope production moves up the "valley of stability" through neutron addition to create isotopes that are either stable or β-decay to stable isotopes. Rapid neutron addition, better known as the r-process, occurs in the extremely high neutron densities found in supernovae. The r-process creates neutron-rich, radioactive isotopes that β-decay to stability, resulting in neutron-rich stable isotopes. Thus, for elements heavier than Ni, the combination of the p-, s-, and r-processes of nucleosynthesis is ultimately responsible for the isotope abundances present in all Solar System materials. A...

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Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

Cited by 104 publications

References 227 publications

The Frequency of Giant Impacts on Earth-Like Worlds

The Frequency of Giant Impacts on Earth-Like Worlds

Hayabusa2: Scientific importance of samples returned from C-type near-Earth asteroid (162173) 1999 JU3

Evidence for supernova injection into the solar nebula and the decoupling of r -process nucleosynthesis

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