Dr. Neumann will give a seminar talk about planetesimal formation and the early Solar System. 

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Time: 21/08/2025 (Thursday) 15:00
Location: Small conference room 3rd floor (#Tencent Meeting：840-5543-5958)
Speaker: Prof. Dr. Wladimir Neumann (Technical University Berlin)
Title: Timescale of Planetesimal Formation in the Carbonaceous Reservoir of the Early Solar System
Abstract: Accretion processes in protoplanetary disks produce a diversity of small bodies that contribute to the composition of planets and can survive as asteroids or comets. There is a predominant paradigm that small bodies played a crucial role in potentially multiple scattering events throughout the solar system and in both early and late accretion of terrestrial planets. Despite a high scientific attention paid to these bodies, their early evolution is not well understood, in particular, the timescales of accretion and thermal processes at different heliocentric distances, as well as the nature of planetesimal populations that produced various groups of present planetary objects. In the last few years, both meteorite analyses and space missions have produced fascinating new data. The JAXA spacecraft Hayabusa2 at the near-Earth asteroid (NEA) Ryugu has revealed a top-shaped rubble-pile object made of hydrated materials similar to carbonaceous chondrites (CC) in their spectral appearance. Similar observations have been made with the NEA Bennu by the NASA mission OSIRIS-REx, raising urgent questions about the nature of these rubble-pile NEA parent bodies. From nucleosynthetic isotopic anomalies, a dichotomy is observed between non-carbonaceous (NC) and carbonaceous (C) meteorites formed within two genetically distinct reservoirs initially located either inside (NC) or outside (C) the orbit of Jupiter that remained isolated for several million years. These isotopic fingerprints can be further combined with precise chronology of meteorite parent bodies and of C-like NEAs to constrain dynamical processes in the early solar system, such as the timescale of Jupiter’s growth, inward scattering of C bodies, their incorporation into the growing terrestrial planets, and delivery of highly volatile species to Earth. By revealing Ryugu’s nature, its relationship to meteorites, and the NEA composition, the data available from the analysis of samples returned by Hayabusa2, OSIRIS-REx and future space missions will provide a powerful boost to the discussion of above cosmochemical topics.
CV: Prof. Dr. Wladimir Neumann is a planetary scientist at the department Planetary Geodesy of the Technical University (TU) Berlin and a Distinguished Professor at the State Key Laboratory of Lunar and Planetary Sciences at the Macau University of Science and Technology. He obtained his PhD degree at the German Aerospace Center (DLR) Berlin and the University of Münster in 2014. He conducted his postdoctoral research at DLR, University of Münster and Heidelberg University. His scientific work focuses on the orbit integration and determination, thermal evolution and differentiation of planetesimals, asteroids, dwarf planets, and icy moons, and on the accretion timescale of planetary objects in the early solar system. Within this research, he contributed to the scientific interpretation of the observations made by the space missions Dawn (NASA) and Hayabusa2 (JAXA) as an instrument Co-I and is involved with the ESA planetary defence mission Hera and the ESA mission Juice to the Jupiter system as science team member.