Hidenori Genda

Hidenori is an expert on a wide range of topics in planet formation, including giant impacts and delivery of volatiles to planets. One of his recent discoveries was to show that giant impacts are occurring around other young stars, suggesting an important role for such events in forging planets throughout the universe. We are currently collaborating on a project to connect accretion history, magma ocean evolution with a steam atmosphere, and internal segregation of a planet during its formation.

Manuscripts authored together:

• Hernlund, J.W., K. Hamano, and H. Genda, Accretion, segregation, and core formation in the long-lived magma ocean regime, in preparation.

George Helffrich

George is a big picture geophysicist who uses a combination of seismology, thermodynamics, and classical geology to elucidate the mysteries of Earth's deep past and deep interior. Most recently George has been revealing fine layering at the top of the liquid outer core and constructing thermodynamical models for precipitation of SiO₂ from the core.

Manuscripts authored together:

• Hirose, K., G. Morard, R. Sinmyo, K. Umemoto, J. Hernlund, G. Helffrich, and S. Labrosse, SiO₂ crystallization and compositional evolution of the Earth's core, Nature, in press.

Kei Hirose

Kei is a big picture geologist who uses high pressure-high temperature experiments to understand the structure, composition, and evolution of Earth's interior. Kei's lab became famous in 2004 for the discovery of a MgSiO₃ post-perovskite phase that becomes stable in Earth's deepest mantle.

Manuscripts authored together:

• Hirose, K., G. Morard, R. Sinmyo, K. Umemoto, J. Hernlund, G. Helffrich, and S. Labrosse, SiO₂ crystallization and compositional evolution of the Earth's core, Nature, in press.
• Ballmer, M.D., C. Houser, J.W. Hernlund, R. Wentzcovitch & K. Hirose, Persistence of Strong Silica-Enriched Domains in the Earth's Lower Mantle, Nature Geoscience, in review.
• Gomi, H., K. Ohta, K. Hirose, S. Labrosse, R. Caracas, M.J. Verstraete, and J.W. Hernlund, The high conductivity of iron and thermal evolution of the Earth's core, Phys. Earth Planet. Int., 224:88-103, 2013. (Click for PDF)
• Nomura, R., H. Ozawa, S. Tateno, K. Hirose, J. Hernlund, S. Muto, H. Ishii, and N. Hiraoka, Spin crossover and iron-rich silicate melt in the Earth's deep mantle, Nature, 473:199-202, 2011. (Click for PDF)

Christine Houser

Christine's current interest is understanding how Earth's present day interior structure reflects our planet's formation and deep time evolution. She is an expert in analysis of vibrations in the Earth recorded at seismographs. Using this data, she produces 3D maps of variations in properties inside the Earth, much like a CT-scan in medical imaging. She uses data from mineral sciences to interpret the results in terms of variations in temperature, composition, and different phases of matter deep beneath our feet.

Manuscripts authored together:

• Hernlund, J.W. and C. Houser, On the distribution of seismic velocities in Earth's deep mantle, Earth Planet. Sci. Lett., 265:423-437, 2008.
• Ballmer, M.D., C. Houser, J.W. Hernlund, R. Wentzcovitch & K. Hirose, Persistence of Strong Silica-Enriched Domains in the Earth's Lower Mantle, Nature Geoscience, in review.

Hiroki Ichikawa

Hiroki creates novel numerical models of fluid flow to understand physical and chemical processes in planetary interiors. He has broad experience in computing, ranging from fluid models to ab initio calculations that simulate individual atoms. We are currently collaborating on two projects: (1) An attempt to better understand the temperatures that prevailed when Earth's core was forged and (2) an ambitious computational effort to better understand the long-term deformation behavior of rocks that controls the evolution of Earth.

Manuscripts authored together:

• Ichikawa, H., J.W. Hernlund and S. Labrosse, Core formation at high temperatures, in preparation.

Matthieu Laneuville

Matthieu studies the coupled evolution of planetary systems as intimately connected networks. We are currently collaborating on a project to understand the evolution of magmas at the bottom of the mantle in the early Earth. Usually we assume that magmas are well-mixed and uniform in composition, however, Matthieu is considering whether heavier (iron-rich) magma could have formed and evolved beneath lighter magma. The scenario allows for higher temperatures to be locked into Earth's core after formation, which may be used as an energy source to help generate the geomagnetic field in ancient times.

Manuscripts authored together:

• Laneuville, M., J.W. Hernlund and S. Labrosse, Evolution of a gravitationally stratified basal magma ocean, in preparation.

Marine Lasbleis

Marine models the evolution of the solid inner core as it crystallizes from the liquid outer core. Since this process records the slow cooling of Earth's core since formation, and is also coupled to generation of the geomagnetic field, it is intimately connected with Earth's long-term thermal and magnetic evolution. This process is also analogous to a very slow crystallization of a magma ocean, providing a window into processes in the early Earth. In particular, the inner core freezing problem should be very similar to the protracted crystallization of a basal magma ocean.

Manuscripts authored together:

• Lasbleis, M., J.W. Hernlund and S. Labrosse, Growth of the inner core by snow fall, in preparation.

Takayuki Saitoh

Takayuki is an expert in the design and implementation of massively parallel smooth particle hydrodynamics (SPH) codes. His codes have been used to model collisions of celestial bodies over vast scales ranging from planets to galaxies. He has been working to develop a new version of the code which is able to simulate sluggish convection in the rocky part of planets. We plan to employ this tool as a means of bridging planet formation and evolution, in addition to using the flow solver to study grain-scale dynamics of deformation in rocks.

Manuscripts authored together:

• Saitoh, T., H. Ichikawa, and J.W. Hernlund, 3D simulation of deformation in a rock containing two distinct crystalline phases, in planning stage.

Maxim Ballmer

Currently Ober-Assistent at ETH-Zurich

Maxim uses computer models of rock deformation and flow inside the Earth to understand how such mantle convection currents shape the structure and evolution of our planet. His work has focused particular attention on the role than melting and composition variations play in both the small and large scale dynamics of the Earth's mantle.

Manuscripts authored together:

• Sakamaki, T., A. Suzuki, E. Ohtani, H. Terasaki, S. Urakawa, Y. Katayama, K. Funakoshi, Y. Wang, J.W. Hernlund, M.D. Ballmer, Ponded melt at the boundary between the lithosphere and asthenosphere, Nature Geoscience, 10.1038/NGEO1982, 2013.
• Ballmer, M.D., C. Houser, J.W. Hernlund, R. Wentzcovitch & K. Hirose, Persistence of Strong Silica-Enriched Domains in the Earth's Lower Mantle, Nature Geoscience, in review.

Razvan Caracas

Ecole Normale Superieure de Lyon

Razvan and I have been working together and discussing numerous projects in recent years. Our most productive collaboration involved a broadly inter-disciplinary study of the electrical conductivity of the Earth's core, which we related to the Earth's thermal evolution and initial core temperature.

Manuscripts authored together:

• Gomi, H., K. Ohta, K. Hirose, S. Labrosse, R. Caracas, M.J. Verstraete, and J.W. Hernlund, The high conductivity of iron and thermal evolution of the Earth's core, Phys. Earth Planet. Int., 224:88-103, 2013. (Click for PDF)

Stéphane Labrosse

Ecole Normale Superieure de Lyon

Stéphane and I have been collaborating in one form or another for more than 15 years.

Manuscripts authored together:

• Laneuville, M., J.W. Hernlund and S. Labrosse, Evolution of a gravitationally stratified basal magma ocean, in preparation.
• Hirose, K., G. Morard, R. Sinmyo, K. Umemoto, J. Hernlund, G. Helffrich, and S. Labrosse, SiO₂ crystallization and compositional evolution of the Earth's core, Nature, in press.
• Labrosse, S., J.W. Hernlund, and N. Coltice, A crystallizing dense magma ocean at the base of the Earth’s mantle, Nature, 450:866-869, 2007. (Click for PDF)

Guillaume Morard

Institut de minéralogie, de physique des matériaux et de cosmochimie, Paris

Guillaume is a fearless high pressure experimentalist who is tackling the most challenging problems in the field of mineral physics. He is a frequent visitor and collaborator at ELSI, and he works on development of frontier techniques such as X-ray characterization of liquids at conditions of Earth's deep interior, among others. He was a key participant in a recent project in which we determined that SiO₂ may crystallize from the Earth's core.

Manuscripts authored together:

• Hirose, K., G. Morard, R. Sinmyo, K. Umemoto, J. Hernlund, G. Helffrich, and S. Labrosse, SiO₂ crystallization and compositional evolution of the Earth's core, Nature, in press.

David Rubie

Bayerisches Geoinstitut, University of Bayreuth, Germany

Dave continues to pursue an ambitious research agenda to bridge models of Earth's accretion and core formation with more general planetary formation theory. For decades he has been a pioneer and one of the most productive scientists in this field.

Manuscripts authored together:

• Jacobson, S.A., D.C. Rubie, J. Hernlund, A. Morbidelli, and M. Nakajima, Formation, stratification and mixing of the cores of Earth and Venus, submitted to Earth and Planetary Science Letters.