The solar chemical composition is an important ingredient in our understanding of the formation, structure, and evolution of both the Sun and our Solar System. Furthermore, it is an essential refer ...

The Chemical Composition of the Sun

Jupiter and Saturn formed in a few million years from a gas-dominated protoplanetary disk, and were susceptible to gas-driven migration of their orbits on timescales of only approximately 100,000 years. Hydrodynamic simulations show that these giant planets can undergo a two-stage, inward-then-outward, migration. The terrestrial planets finished accreting much later and their characteristics, including Mars' small mass, are best reproduced by starting from a planetesimal disk with an outer edge at about one astronomical unit from the Sun (1 AU is the Earth-Sun distance). Here we report simulations of the early Solar System that show how the inward migration of Jupiter to 1.5 AU, and its subsequent outward migration, lead to a planetesimal disk truncated at 1 AU; the terrestrial planets then form from this disk over the next 30-50 million years, with an Earth/Mars mass ratio consistent with observations. Scattering by Jupiter initially empties but then repopulates the asteroid belt, with inner-belt bodies originating between 1 and 3 AU and outer-belt bodies originating between and beyond the giant planets. This explains the significant compositional differences across the asteroid belt. The key aspect missing from previous models of terrestrial planet formation is the substantial radial migration of the giant planets, which suggests that their behaviour is more similar to that inferred for extrasolar planets than previously thought.

A low mass for Mars from Jupiter's early gas―driven migration

The formation of planetesimals, the kilometer-sized planetary precursors, is still a puzzling process. Considerable progress has been made over the past years in the physical description of the first stages of planetesimal formation, owing to extensive laboratory work. This review examines the experimental achievements and puts them into the context of the dust processes in protoplanetary disks. It has become clear that planetesimal formation starts with the growth of fractal dust aggregates, followed by compaction processes. As the dust-aggregate sizes increase, the mean collision velocity also increases, leading to the stalling of the growth and possibly to fragmentation, once the dust aggregates have reached decimeter sizes. A multitude of hypotheses for the further growth have been proposed, such as very sticky materials, secondary collision processes, enhanced growth at the snow line, or cumulative dust effects with gravitational instability. We will also critically review these ideas.

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The Growth Mechanisms of Macroscopic Bodies in Protoplanetary Disks

We present new analytical data of major and trace elements for the geological MPI-DING glasses KL2-G, ML3B-G, StHs6/80-G, GOR128-G, GOR132-G, BM90/21-G, T1-G, and ATHO-G. Different analytical methods were used to obtain a large spectrum of major and trace element data, in particular, EPMA, SIMS, LA-ICPMS, and isotope dilution by TIMS and ICPMS. Altogether, more than 60 qualified geochemical laboratories worldwide contributed to the analyses, allowing us to present new reference and information values and their uncertainties (at 95% confidence level) for up to 74 elements. We complied with the recommendations for the certification of geological reference materials by the International Association of Geoanalysts (IAG). The reference values were derived from the results of 16 independent techniques, including definitive (isotope dilution) and comparative bulk (e.g., INAA, ICPMS, SSMS) and microanalytical (e.g., LA-ICPMS, SIMS, EPMA) methods. Agreement between two or more independent methods and the use of definitive methods provided traceability to the fullest extent possible. We also present new and recently published data for the isotopic compositions of H, B, Li, O, Ca, Sr, Nd, Hf, and Pb. The results were mainly obtained by high-precision bulk techniques, such as TIMS and MC-ICPMS. In addition, LA-ICPMS and SIMS isotope data of B, Li, and Pb are presented.

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MPI-DING reference glasses for in situ microanalysis: New reference values for element concentrations and isotope ratios

The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.

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Comet 81P/Wild 2 under a microscope.

Engrand3, Y. Kebukawa4, B. De Gregorio5, L. Bonal6, L. Remusat7, R. Stroud5, E. Quirico6, L. R. Nittler2, M. Hashiguchi8, M. Komatsu9, E. Dartois10, J. Mathurin11, J. Duprat7, T. Okumura12, Y. Takahashi12, Y. Takeichi13, D. Kilcoyne14, S. Yamashita13, A. Dazzi11, A. Deniset-Besseau11, S. Sandford15, Z. Martins16, Y. Tamenori17, T. Ohigashi18, H. Suga17, D. Wakabayashi13, M. Verdier-Paoletti7, S. Mostefaoui7, G. Montagnac19, J. Barosch2, K. Kamide1, M. Shigenaka1, L. Bejach3, T. Noguchi20, H. Yurimoto21, T. Nakamura22, R. Okazaki23, H. Naraoka23, K. Sakamoto24, S. Tachibana12,24, S. Watanabe8, and Y. Tsuda24, 1Hiroshima Univ., 1-3-1 Kagamiyama, HigashiHiroshima, Hiroshima 739-8526, Japan. 2Carnegie Institution of Washington, USA. 3IJCLab, Univ. ParisSaclay/CNRS, France. 4Yokohama National Univ., Japan. 5U.S. Naval Research Laboratory, USA, 6Université Grenoble Alpes, France. 7Muséum national d'Histoire naturelle, France. 8Nagoya Univ., Japan. 9The Graduate Univ. for Advanced Studies (Sokendai), Japan. 10ISMO, Univ. Paris-Saclay/CNRS, France. 11ICP, Univ. Paris-Saclay/CNRS, France. 12Univ. of Tokyo, Japan, 13High Energy Accelerator Research Organization, Japan. 14Advanced Light Source, USA. 15NASA Ames Research Center, USA. 16Instituto Superior Técnico, Portugal. 17SPring8, Japan. 18UVSOR, IMS, Japan. 19ENS Lyon, France, 20Kyoto Univ., Japan. 21Hokkaido Univ., Japan. 22Tohoku Univ., Japan. 23Kyushu Univ., Japan. 24ISAS, JAXA Japan.

Macromolecular organic matter in c-type asteroid ryugu

topically Heterogeneous Ices. J. Rojas, J. Duprat, E. Dartois, T-D. Wu, C. Engrand, L. R. Nittler, N. Bardin, B. Augé, Ph. Boduch, H. Rothard, M. Chabot, L. Delauche, S. Mostefaoui, L. Rémusat, R. M. Stroud, B. Guérin; Univ. Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France (Julien.Rojas@ijclab.in2p3.fr), 2 IMPMC, CNRS-MNHN-Sorbonne Univ., 75005 Paris, France, 3 Univ. Paris-Saclay, CNRS, ISMO, 91405 Orsay, France, 4 Institut Curie, PSL Univ., Univ. Paris-Saclay, CNRS UMS2016, Inserm US43, Multimodal Imaging Center, 91405 Orsay, France, Earth and Planets Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA, IPAG, Univ. Grenoble Alpes, CNRS, 38000 Grenoble, France, CIMAP, 14070 Caen, France, Naval Research Laboratory, Washington, DC 20375, USA

Smail Mostefaoui

Papers

Macromolecular organic matter in c-type asteroid ryugu

The Isotopic Composition of Ultra-Carbonaceous Antarctic Micrometeorites Organics, Ion-Irradiation of Isotopically Heterogeneous Ices.