Well-resolved variations in the formation ages for Ca–Al-rich inclusions in the early Solar System

MacPherson, G. J.; Kita, N. T.; Ushikubo, T.; Bullock, E. S.; Davis, A. M.

doi:10.1016/j.epsl.2012.03.010

Cited by 118 publications

(131 citation statements)

References 20 publications

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“…These objects define the canonical 26 Al/ 27 Al ratio of 5 10 5 , which is widely thought to reflect the initial 26 Al abundance of the Solar System. Some CAIs define lower initial 26 Al / Larsen et al (2011), Hutcheon and Hutchison (1989), Kita et al (2000Kita et al ( , 2013, Kita and Ushikubo (2012), Kunihiro et al (2004), Kurahashi et al (2008), MacPherson et al (2012), Olsen et al (2013), Ushikubo et al (2013), and or alternatively, remelting events within 300,000 years of CAI condensation (MacPherson et al 2012). In contrast, chondrules recorded systematically lower initial 26 Al/ 27 Al ratios.…”

Section: The 26 Al-26 Mg Decay Systemmentioning

confidence: 89%

Chondrules: Ubiquitous Chondritic Solids Tracking the Evolution of the Solar Protoplanetary Disk

Bizzarro

Connelly

Krot

2017

Formation, Evolution, and Dynamics of Young Solar Systems

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Chondrite meteorites are samples of primitive asteroidal bodies that have escaped melting and differentiation. The only record of our Solar System's formative stages comes from the earliest solids preserved in chondrites, namely millimetre-to centimetre-sized calcium-aluminium-rich inclusions (CAIs) and chondrules. These solids formed by transient heating events during the lifetime of the solar protoplanetary disk. Collectively, CAIs and chondrules provide timesequenced samples allowing us to probe the composition of the disk material that accreted to form planetesimals and planets. Here, we showcase the current stateof-the-art data with respect to the chronology and stable isotopic compositions of individual chondrules from various chondrite groups and discuss how these data can be used to provide novel insights into the thermal and chemical evolution of the solar protoplanetary disk, including mass transport processes.

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Section: The 26 Al-26 Mg Decay Systemmentioning

confidence: 89%

Chondrules: Ubiquitous Chondritic Solids Tracking the Evolution of the Solar Protoplanetary Disk

Bizzarro

Connelly

Krot

2017

Formation, Evolution, and Dynamics of Young Solar Systems

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“…Because H-event supernova material is relatively depleted in r-process isotopes A ≤ 140 (e.g., Mo, Ba) and relatively enriched in r-process isotopes 140 ≤ A ≤ 200 (e.g., Nd, Sm) (29), incomplete mixing of various supernova-derived material could, in principle, produce the observed isotopic variations. CAIs are thought to have formed in the innermost portion of the accreting nebular disk (15) in a short time frame, possibly as short as 20-50 thousand years (36)(37)(38). Therefore, these CAIs would have preserved a snapshot of the isotopic composition from the wellmixed CAI-forming region close to the young Sun.…”

Section: Resultsmentioning

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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“…Such is not the case. MacPherson et al (2012a) demonstrated that spinel enclosed within anorthite in a type B CAI has extensively exchanged its magnesium isotopes. In fact, this observation is entirely consistent with experimental measurements of magnesium diffusion coefficients in spinel, which turn out to be comparable to those in anorthite and much faster than those in pyroxene or melilite (e.g., Ito and Ganguly, 2009;Liermann and Ganguly, 2002;Sheng et al, 1992).…”

Section: Spinelmentioning

confidence: 98%

“…Yet, during the high-temperature processing in the solar nebula that formed the CAIs, the two isotopic reservoirs did not mix. Given that live 26 Al apparently was quite widespread in the early solar nebula at an initial abundance ratio ( 26 Al/ 27 Al) 0 ¼ 5.2 Â 10 À5 (Jacobsen et al, 2008;MacPherson et al, 2012a;Villeneuve et al, 2009), how then can its absence from FUN CAIs be explained? If initial 26 Al/ 27 Al ratio was perfectly uniform throughout the nebula at the time the first CAI precursors formed, then the magnesium isotopic differences between FUN and normal CAIs would suggest that the FUN CAIs formed or were reprocessed several Ma later than the normal CAIs.…”

Section: Fun Cais and Hibonite Grainsmentioning

confidence: 98%

Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

MacPherson

2014

Treatise on Geochemistry

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Well-resolved variations in the formation ages for Ca–Al-rich inclusions in the early Solar System

Cited by 118 publications

References 20 publications

Chondrules: Ubiquitous Chondritic Solids Tracking the Evolution of the Solar Protoplanetary Disk

Chondrules: Ubiquitous Chondritic Solids Tracking the Evolution of the Solar Protoplanetary Disk

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

Calcium–Aluminum-Rich Inclusions in Chondritic Meteorites

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