Main Focus
I am an isotope geo-/cosmochemist with a strong interest in deepening our understanding of the formation and evolution of the early Solar System, as well as the accretion and differentiation history of Earth. In particular, my research aims to address the questions:
What were
the dominant mixing and fractionation processes in the earliest stages of Solar
System history, and what is the chronology of these events? What are the
formation and thermal evolution paths of asteroids and their precursors?
How, when, and where did planetary building blocks accrete to form Earth and
other planetary bodies?
To
elucidate these questions, I search for isotopic variations and chemical
signatures in meteorites and their components, as well as in terrestrial rocks.
Specifically, I combine radiometric dating (chronology), mass-independent
isotope anomalies of nucleosynthetic origin (tracers of the genetic heritage),
and elemental and mass-dependent isotope fractionations (tracers of kinetic and
equilibrium processes) to address when, where, and how nebular and planetary
processes took place.
Curriculum Vitae
Education:
2016 –2020 Doctor of Natural Sciences, University of Münster, Germany
2014 –2016 Master of Science – Geosciences / Earth Sciences, University of Münster, Germany
2011–2014 Bachelor of Science – Geosciences / Earth Sciences, University of Münster, Germany
Employment:
2024–Present Scientist, Max Planck Institute for Solar System Research, Göttingen, Germany
2021–2024 Post-Doctoral Associate, University of Maryland, Department of Geology, United States
2021 Post-Doctoral Researcher, University of Münster, Institut für Planetologie, Germany
2016–2020 Research Assistant, University of Münster, Institut für Planetologie, Germany
2014–2016 Student Assistant, University of Münster, Institut für Planetologie, Germany
Awards:
2022 Bradley Paper Award (Runner-up) – The Geological Society of Washington2021 Paul Pellas-Graham Ryder Award – The Meteoritical Society and the Geological Society of America
2018 Outstanding Student Presentation Award – American Geophysical Union
2018 Wiley Award – The Meteoritical Society
Selected publications:
Hellmann, J.L., Van Orman, J.A. and Kleine, T. (2024) Hf-W isotope systematics of enstatite chondrites: Parent body chronology and origin of Hf-W fractionations among chondritic meteorites. Earth and Planetary Science Letters 626, 118518. https://doi.org/10.1016/j.epsl.2023.118518
Hellmann, J.L., Schneider, J.M., Wölfer, E., Drążkowska, J., Jansen, C. A., Hopp, T., Burkhardt, C. and Kleine, T. (2023) Origin of isotopic diversity among carbonaceous chondrites. The Astrophysical Journal Letters 946, L34. https://doi.org/10.3847/2041-8213/acc102
Hellmann, J.L., Hopp, T., Burkhardt, C., Becker, H., Fischer-Gödde, M. and Kleine, T. (2021) Tellurium isotope cosmochemistry: Implications for volatile fractionation in chondrite parent bodies and origin of the late veneer. Geochimica et Cosmochimica Acta 309, 313-328. https://doi.org/10.1016/j.gca.2021.06.038
Hellmann, J.L., Hopp, T., Burkhardt, C. and Kleine, T. (2020) Origin of volatile element depletion among carbonaceous chondrites. Earth and Planetary Science Letters 549, 116508. https://doi.org/10.1016/j.epsl.2020.116508
Hellmann, J.L., Kruijer, T.S., Van Orman, J.A., Metzler, K. and Kleine, T. (2019) Hf-W chronology of ordinary chondrites. Geochimica et Cosmochimica Acta 258, 290-309. https://doi.org/10.1016/j.gca.2019.05.040