Chondrite Recipe from Accretion Disk modeling and Laboratory Experiments – CRADLE

We have developed a numerical model that simulates the formation and evolution of the disk around a star in formation. This model allows for the first time to follow the evolution of grains coming from the interstellar medium during their injection into the disk, their eventual vaporization at very high temperature near the star, and to follow the condensation, from the gas produced, of the first solar-system solids. The code couples the physics of the disk, for example heating of the disk or transport of gas and grains, with equilibrium thermodynamics. This allows to predict, as a function of time, the composition of the solids which will be able to condense or transform at various places in the disk. The back and forth between these predictions and the specific observations made in this project on the components of the primitive meteorites, for example on the age of these components or on the variations of their isotopic compositions, allows to identify the key processes in the evolution of the disk and to explain observations, up to now not understood, on the composition of primitive meteorites.

One of the major results of the project is to show that the physics of the disk that builds up around the Sun predicts the formation of chemical, isotopic and mineralogical zonations in the disk that correspond, to the first order, to what is observed in the different classes of primitive meteorites, www.youtube.com/watch, [Pignatale et al., 2018].
The model explains for instance why refractory solids can only be condensed during the first ˜50 kyr, as indicated by the U-Pb and 26Al dating of refractory inclusions in primitive chondrites. This period of the disk is in fact the only one when refractory presolar dust is injected in regions with T>1650 K and is thus vaporized resulting in a gas rich in refractory elements. This gas will spread outwards rapidly, will cool, and condense refractory solids.
A mineralogical and chemical zoning of the disk, corresponding to the main types of chondrites and explaining why refractory grains are found in comets, is produced rapidly, in the first 300 000 years of the solar system. The simulations show that this zoning will partly survive at 1.5 Myr. Refinements of this initial code have been used to explain the distribution of interstellar isotopic anomalies [Jacquet et al., 2019] and of short-lived 26Al [Pignatale et al., 2019] in the disk. Following models were developed to study the effects of the presence of a dead zone on planetesimals formation [Charnoz et al., 2019] or of pressure gaps at the snow line [Charnoz et al., 2021].
The conditions of irradiation of solids in the disk around the protosun were quantitatively determined for the first time [Sossi et al., 2017]. Irradiation models reproducing the amount of 50V and 10Be coproduced by irradiation, as implied by the isotopic variations observed in various refractory solids of primitive meteorites, require that these solids were irradiated for less than 300 years at ˜ 0.1 AU from the active protosun. This is a key constraint to disk models. Similarly, time constraints on the formation of the dust are key. High precision studies of long-lived U-Th-Pb and short-lived Al-Mg systems in chondrules allowed to demonstrate the potential consequence on age estimates of forming chondrules from precursor solids having various formation histories in the disk (formed at different times, under different fO2, or in an isotopically heterogeneous disk) [Blichert-Toft et al., 2020; Deng et al., 2021]. The conditions of condensation of silicate dust, precursor of the various components of chondrites, were further constrained from Si isotopic compositions [Martins et al., 2020].

The results of CRADLE have opened the way to refined simulations of the early evolution of the solar protoplanetary disk and to further interactions between astrophysics and cosmochemistry.
The CRADLE project and its results have led to the development of two other projects that have been submitted to and selected by the ANR, and are also the source of part of an ERC consolidator project. These 3 projects have CRADLE members as PIs.
- DISKBUILD (Projet-ANR-20-CE49-0006): Early planetary formation processes during the assembly of the protoplanetary disk. PI S. Charnoz (IPGP), partners IPGP (Paris), CRAL (Lyon) and OCA (Nice).
- MIFs (Project-ANR-20-CE49-0011): Mass-independent isotopic fractionations in cosmochemistry. PI M. Chaussidon (IPGP), partners IPGP (Paris), IMPMC (Paris), LCT (Paris), LSPM (Villetaneuse).
- METAL (ERC Consolidator 2020 PE10, ERC-2020-COG): Making terrestrial planets. PI F. Moynier (IPGP).

The results from CRADLE were at the origin of 14 papers in front journals of the field (Nature Astron., Astrophys. J., PNAS, Geochim. Cosmochim. Acta, Astron. Astrophys.) and of presentations to meetings. The model developed here was very well received by the community and was influential. It was for instance selected to be featured in the blog Astrobite (https://astrobites.org/2018/10/31/the-spooky-origins-of-the-solar-system/) and the paper by Pignatale et al. (2018) has already been quoted 38 times. Similarly, the paper on irradiation by Sossi et al. (2017) has been quoted 45 times.

Selected publications:
Blichert-Toft J., Göpel C., Chaussidon M. & Albarède F. (2020) The Th/U of chondrules and the age of the Solar system. Geochim. Cosmochim. Acta 280, 378-394.
Charnoz S., Avice G., Hyodo R., Pignatale F. C. & Chaussidon M. (2021) Forming pressure traps at the snow line to isolate isotopic reservoirs in the absence of a planet. Astron. Astrophys. 652, A35. (https://doi.org/10.1051/0004-6361/202038797)
Charnoz S., Pignatale F. C., Hyodo R., Mahan B., Chaussidon M., Siebert J. & Moynier F. (2019) Planetesimal formation in an evolving protoplanetary disk with a dead-zone. Astron. Astrophys. 627, A50, 16p, doi.org/10.1051/0004-6361/201833216.
Deng Z., Chaussidon M., Ebel D; S., Villeneuve J., Moureau J. & Moynier F. (2021) Simultaneous determination of mass-dependent Mg isotopic variations and radiogenic 26Mg by laser ablation-MC-ICP-MS and implications for the formation of chondrules. Geochim. Cosmochim. Acta 299, 163-183
Jacquet E., Pignatale F. C., Chaussidon M. & Charnoz S. (2019) Fingerprints of the protosolar cloud collapse in the Solar system II: nucleosynthetic anomalies in meteorites. Astrophys. J. 884:32.
Martins Pimentel R., Chaussidon M., Deng Z. Moynier F. (2020) A condensation origin for the mass-dependent silicon isotopic variations in Allende components: implications for complementarity. Earth Planet. Sci. Lett. 564, 116678.
Pignatale F. C., Jacquet E., Chaussidon M. & Charnoz S. (2019) Fingerprints of the protosolar cloud collapse in the Solar system I: distribution of presolar short-lived 26Al. Astrophys. J. 884:31.
Pignatale F.C., Charnoz S., Chaussidon M. & Jacquet E. (2018) Making the planetary material diversity during the early assembly of the Solar system, Astrophys. J. Lett. 867, L23.
Sossi P.A., Moynier F., Chaussidon M., Villeneuve J., Kato C. & Gounelle M. (2017) Early Solar System irradiation revealed by linked vanadium and beryllium isotope variations in meteorites. Nature Astronomy 1, 0055.

The goal of the project CRADLE (Chondrite Recipe from Accretion Disk modeling and Laboratory Experiments) is to attempt for the first time to (i) assemble observations and analyses made with an unprecedented resolution of several primitive chondritic meteorites and (ii) develop in parallel a numerical model of the Solar protoplanetary disk, which will be built to integrate all these new observations. We want to study whether numerical simulations based on our knowledge of the physics of the solar protoplanetary disk and of disks observed around protostars can reproduce the formation of primitive planetesimals such as the parent bodies of chondrites. One key aspect will be to integrate two different approaches, from astrophysics and from cosmochemistry. CRADLE is expected to advance our understanding of the early evolution of the disk, its physics and chemistry, and of the formation of planetesimals, which is the least understood step towards the formation of terrestrial planets.
The relevance of the project CRADLE comes from recent observations of accretion disks around young stars analogous to our forming Sun, and of chondritic meteorites. Chondrites are understood as "sediments" having accumulated in the accretion disk from materials formed very early in the Solar nebula or inherited from the presolar molecular cloud, making them a unique window on the early solar system. All these observations lead to several key questions related to the origin of the first solids and the first planetary objects in the protoplanetary disk. There is yet no model able to answer these questions. An apparent conflict exists between (i) the nature of chondrites, which are made from components (refractory inclusions, chondrules, fine-grained matrix) having very different origins in the accretion disk (based on parameters such as temperature, pressure, mineralogy, chemical and isotopic composition, ...) and formation ages extending over several million years, and (ii) our understanding of the standard dynamical, thermodynamical and chemical spatio-temporal evolution of the protoplanetary disk, which predict rapid evolution and mixing.
Recent developments of numerical codes allow designing simulations that are capable of following the infall of the presolar cloud, the formation and the evolution of the protoplanetary disk, and to take into account detailed physico-chemical constraints coming from the observations of chondritic meteorites. Similarly, recent analytical developments in the study of extra-terrestrial matter have made it possible to gather observations (such as the formation ages of the different components of a chondrite) that describe precisely the complexity of a chondrite. CRADLE is based on going back and forth between numerical simulations and chemical and isotopic measurements of chondrites, each part feeding into the other.