Origin of uranium isotope variations in early solar nebula condensates

François L. H. Tissot; Nicolas Dauphas; Lawrence Grossman

doi:10.1126/sciadv.1501400

Origin of uranium isotope variations in early solar nebula condensates

Science Advances ◽

10.1126/sciadv.1501400 ◽

2016 ◽

Vol 2 (3) ◽

pp. e1501400 ◽

Cited By ~ 30

Author(s):

François L. H. Tissot ◽

Nicolas Dauphas ◽

Lawrence Grossman

Keyword(s):

High Temperature ◽

Solar System ◽

Neutron Capture ◽

Solar Nebula ◽

Isotopic Fractionation ◽

Uranium Isotope ◽

Solar System Formation ◽

System Composition ◽

Isotopic Variations ◽

Isotope Measurements

High-temperature condensates found in meteorites display uranium isotopic variations (235U/238U), which complicate dating the solar system’s formation and whose origin remains mysterious. It is possible that these variations are due to the decay of the short-lived radionuclide247Cm (t1/2= 15.6 My) into235U, but they could also be due to uranium kinetic isotopic fractionation during condensation. We report uranium isotope measurements of meteoritic refractory inclusions that reveal excesses of235U reaching ~+6% relative to average solar system composition, which can only be due to the decay of247Cm. This allows us to constrain the247Cm/235U ratio at solar system formation to (7.0 ± 1.6) × 10−5. This value provides new clues on the universality of the nucleosyntheticr-process of rapid neutron capture.

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Strong isotope effect in the VUV photodissociation of HOD: A possible origin of D/H isotope heterogeneity in the solar nebula

Science Advances ◽

10.1126/sciadv.abg7775 ◽

2021 ◽

Vol 7 (30) ◽

pp. eabg7775

Author(s):

Zijie Luo ◽

Yarui Zhao ◽

Zhichao Chen ◽

Yao Chang ◽

Su-e Zhang ◽

...

Keyword(s):

Solar System ◽

Isotope Effect ◽

Quantum State ◽

Solar Nebula ◽

Isotopic Fractionation ◽

Branching Ratios ◽

Terrestrial Planets ◽

Isotopic Ratios ◽

Alternative Source ◽

Photochemical Models

The deuterium versus hydrogen (D/H) isotopic ratios are important to understand the source of water on Earth and other terrestrial planets. However, the determinations of D/H ratios suggest a hydrogen isotopic diversity in the planetary objects of the solar system. Photochemistry has been suggested as one source of this isotope heterogeneity. Here, we have revealed the photodissociation features of the water isotopologue (HOD) at λ = 120.8 to 121.7 nm. The results show different quantum state populations of OH and OD fragments from HOD photodissociation, suggesting strong isotope effect. The branching ratios of H + OD and D + OH channels display large isotopic fractionation, with ratios of 0.70 ± 0.10 at 121.08 nm and 0.49 ± 0.10 at 121.6 nm. Because water is abundant in the solar nebula, photodissociation of HOD should be an alternative source of the D/H isotope heterogeneity. This isotope effect must be considered in the photochemical models.

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The Movement of Small Particulate Matter in the Early Solar System and the Formation of Satellites

Highlights of Astronomy ◽

10.1017/s1539299600002227 ◽

1974 ◽

Vol 3 ◽

pp. 483-485

Author(s):

T. Gold

Keyword(s):

Particulate Matter ◽

Solar System ◽

Vapor Pressure ◽

Solar Nebula ◽

Satellite Orbits ◽

Formation Processes ◽

Early Solar System ◽

Solar System Formation ◽

Tidal Friction ◽

Collision Orbits

Satellites are a common feature in the solar system, and all planets on which satellite orbits would be stable possess them. (For Mercury the solar perturbation is too large, and the retrograde spin of Venus would cause satellites to spiral in to the planet through tidal friction.) An explanation of the formation of satellites must hence be one which makes the phenomenon exceedingly probable at some stage in the solar system formation processes, and very improbable processes like a capture cannot be the answer in most cases.Small particulate matter must have been very abundant in the early solar nebula. Such particulate matter must have existed both from the first condensation of the low vapor pressure components of the gas in the first round, and it must also have been composed of material scattered from impacts after some major bodies had begun to form, frequently finding themselves no doubt on collision orbits.

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Heating events in the nascent solar system recorded by rare earth element isotopic fractionation in refractory inclusions

Science Advances ◽

10.1126/sciadv.abc2962 ◽

2021 ◽

Vol 7 (2) ◽

pp. eabc2962

Author(s):

J. Y. Hu ◽

N. Dauphas ◽

F. L. H. Tissot ◽

R. Yokochi ◽

T. J. Ireland ◽

...

Keyword(s):

Rare Earth ◽

Earth Element ◽

Main Sequence ◽

Solar Nebula ◽

Isotopic Fractionation ◽

Main Sequence Stars ◽

Refractory Elements ◽

Stage Process ◽

Group Ii ◽

Isotopic Variations

Equilibrium condensation of solar gas is often invoked to explain the abundance of refractory elements in planets and meteorites. This is partly motivated, by the observation that the depletions in both the least and most refractory rare earth elements (REEs) in meteoritic group II calcium-aluminum–rich inclusions (CAIs) can be reproduced by thermodynamic models of solar nebula condensation. We measured the isotopic compositions of Ce, Nd, Sm, Eu, Gd, Dy, Er, and Yb in eight CAIs to test this scenario. Contrary to expectation for equilibrium condensation, we find light isotope enrichment for the most refractory REEs and more subdued isotopic variations for the least refractory REEs. This suggests that group II CAIs formed by a two-stage process involving fast evaporation of preexisting materials, followed by near-equilibrium recondensation. The calculated time scales are consistent with heating in events akin to FU Orionis– or EX Lupi–type outbursts of eruptive pre–main-sequence stars.

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An Overview of Comet Composition

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311025038 ◽

2011 ◽

Vol 7 (S280) ◽

pp. 261-274 ◽

Cited By ~ 18

Author(s):

Dominique Bockelée-Morvan

Keyword(s):

Solar System ◽

Molecular Cloud ◽

Solar Nebula ◽

Short Review ◽

Present Knowledge ◽

Physical Processes ◽

Solar System Formation ◽

System Formation ◽

Early Phases

AbstractComets are made of ices, organics and minerals that record the chemistry of the outer regions of the primitive solar nebula where they agglomerated 4.6 Gyr ago. Compositional analyses of comets can provide important clues on the chemical and physical processes that occurred in the early phases of Solar System formation, and possibly in the natal molecular cloud that predated the formation of the solar nebula. This paper presents a short review of our present knowledge of the composition of comets. Implications for the origin of cometary materials are discussed.

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History of the solar nebula from meteorite paleomagnetism

Science Advances ◽

10.1126/sciadv.aba5967 ◽

2021 ◽

Vol 7 (1) ◽

pp. eaba5967

Author(s):

Benjamin P. Weiss ◽

Xue-Ning Bai ◽

Roger R. Fu

Keyword(s):

Solar System ◽

Solar Nebula ◽

Protoplanetary Disks ◽

Outer Solar System ◽

The Sun ◽

Planetary Formation ◽

Solar System Formation ◽

Astronomical Observations ◽

Accretion Rates ◽

History Of

We review recent advances in our understanding of magnetism in the solar nebula and protoplanetary disks (PPDs). We discuss the implications of theory, meteorite measurements, and astronomical observations for planetary formation and nebular evolution. Paleomagnetic measurements indicate the presence of fields of 0.54 ± 0.21 G at ~1 to 3 astronomical units (AU) from the Sun and ≳0.06 G at 3 to 7 AU until >1.22 and >2.51 million years (Ma) after solar system formation, respectively. These intensities are consistent with those predicted to enable typical astronomically observed protostellar accretion rates of ~10−8M⊙year−1, suggesting that magnetism played a central role in mass transport in PPDs. Paleomagnetic studies also indicate fields <0.006 G and <0.003 G in the inner and outer solar system by 3.94 and 4.89 Ma, respectively, consistent with the nebular gas having dispersed by this time. This is similar to the observed lifetimes of extrasolar protoplanetary disks.

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Evidence from achondrites for a temporal change in Nd nucleosynthetic anomalies within the first 1.5 million years of the inner solar system formation

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2021.116968 ◽

2021 ◽

Vol 566 ◽

pp. 116968

Author(s):

Paul Frossard ◽

Zhiguo Guo ◽

Mary Spencer ◽

Maud Boyet ◽

Audrey Bouvier

Keyword(s):

Solar System ◽

Temporal Change ◽

Solar System Formation ◽

System Formation

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A unique basaltic micrometeorite expands the inventory of solar system planetary crusts

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0900328106 ◽

2009 ◽

Vol 106 (17) ◽

pp. 6904-6909 ◽

Cited By ~ 32

Author(s):

Matthieu Gounelle ◽

Marc Chaussidon ◽

Alessandro Morbidelli ◽

Jean-Alix Barrat ◽

Cécile Engrand ◽

...

Keyword(s):

Solar System ◽

Mineral Chemistry ◽

Carbonaceous Chondrites ◽

Isotopic Data ◽

Solar System Formation ◽

Sample Return ◽

Dust Transport ◽

Element Abundances ◽

Transport Dynamics ◽

Sample Return Mission

Micrometeorites with diameter ≈100–200 μm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the first basaltic micrometeorite (MM40). This micrometeorite is unlike any other basalt known in the solar system as revealed by isotopic data, mineral chemistry, and trace element abundances. The discovery of a new basaltic asteroidal surface expands the solar system inventory of planetary crusts and underlines the importance of micrometeorites for sampling the asteroids' surfaces in a way complementary to meteorites, mainly because they do not suffer dynamical biases as meteorites do. The parent asteroid of MM40 has undergone extensive metamorphism, which ended no earlier than 7.9 Myr after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family. The ability to retrieve such a wealth of information from this tiny (a few micrograms) sample is auspicious some years before the launch of a Mars sample return mission.

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Nitrogen and hydrogen fractionation in high-mass star-forming cores from observations of HCN and HNC

Astronomy and Astrophysics ◽

10.1051/0004-6361/201730576 ◽

2018 ◽

Vol 609 ◽

pp. A129 ◽

Cited By ~ 12

Author(s):

L. Colzi ◽

F. Fontani ◽

P. Caselli ◽

C. Ceccarelli ◽

P. Hily-Blant ◽

...

Keyword(s):

Solar System ◽

Solar Nebula ◽

Rotational Transition ◽

High Mass ◽

Evolutionary Stage ◽

Mass Star ◽

Stellar Cluster ◽

Star Forming ◽

Star Forming Regions ◽

Dense Cores

The ratio between the two stable isotopes of nitrogen, 14N and 15N, is well measured in the terrestrial atmosphere (~272), and for the pre-solar nebula (~441, deduced from the solar wind). Interestingly, some pristine solar system materials show enrichments in 15N with respect to the pre-solar nebula value. However, it is not yet clear if and how these enrichments are linked to the past chemical history because we have only a limited number of measurements in dense star-forming regions. In this respect, dense cores, which are believed to be the precursors of clusters and also contain intermediate- and high-mass stars, are important targets because the solar system was probably born within a rich stellar cluster, and such clusters are formed in high-mass star-forming regions. The number of observations in such high-mass dense cores has remained limited so far. In this work, we show the results of IRAM-30 m observations of the J = 1−0 rotational transition of the molecules HCN and HNC and their 15N-bearing counterparts towards 27 intermediate- and high-mass dense cores that are divided almost equally into three evolutionary categories: high-mass starless cores, high-mass protostellar objects, and ultra-compact Hii regions. We have also observed the DNC(2–1) rotational transition in order to search for a relation between the isotopic ratios D/H and 14N/15N. We derive average 14N/15N ratios of 359 ± 16 in HCN and of 438 ± 21 in HNC, with a dispersion of about 150–200. We find no trend of the 14N/15N ratio with evolutionary stage. This result agrees with what has been found for N2H+ and its isotopologues in the same sources, although the 14N/15N ratios from N2H+ show a higher dispersion than in HCN/HNC, and on average, their uncertainties are larger as well. Moreover, we have found no correlation between D/H and 14N/15N in HNC. These findings indicate that (1) the chemical evolution does not seem to play a role in the fractionation of nitrogen, and that (2) the fractionation of hydrogen and nitrogen in these objects is not related.

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Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1518183113 ◽

2016 ◽

Vol 113 (8) ◽

pp. 2011-2016 ◽

Cited By ~ 84

Author(s):

Elishevah M. M. E. Van Kooten ◽

Daniel Wielandt ◽

Martin Schiller ◽

Kazuhide Nagashima ◽

Aurélien Thomen ◽

...

Keyword(s):

Solar System ◽

Thermal Processing ◽

Molecular Cloud ◽

Decay Product ◽

Isotopic Signature ◽

Carbonaceous Chondrites ◽

Outer Solar System ◽

Precursor Material ◽

System Composition ◽

Cloud Material

The short-lived 26Al radionuclide is thought to have been admixed into the initially 26Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent 54Cr and 26Mg*, the decay product of 26Al. This correlation is interpreted as reflecting progressive thermal processing of in-falling 26Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived 26Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a 26Mg*-depleted and 54Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived 26Al. The 26Mg* and 54Cr compositions of bulk metal-rich chondrites require significant amounts (25–50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants.

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