Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Futoshi Takahashi Last modified date:2019.06.12

Associate Professor / Dynamics, Structure and Evolution of Earth and Planets / Department of Earth and Planetary Sciences / Faculty of Sciences


Papers
1. Futoshi Takahashi, Hisayoshi Shimizu, Hideo Tsunakawa, Mercury’s anomalous magnetic field caused by a symmetry-breaking self-regulating dynamo, Nature Communications, doi: 10.1038/s41467-018-08213-7, 10, 2019.01, The discovery of Mercury’s unusually axisymmetric, anomalously axially offset dipolar magnetic field reveals a new regime of planetary magnetic fields. The cause of the offset dipole remains to be resolved, although some exotic models have been proposed. Deciphering why Mercury has such an anomalous field is crucial not only for understanding the internal dynamics, evolutionary history and origin of the planet, but also for establishing the general dynamo theory. Here we present numerical dynamo models, where core convection is driven as thermo-compositional, double-diffusive convection surrounded by a thermally stably stratified layer. We show that the present models produce magnetic fields similar in morphology and strength to that of Mercury. The dynamo-generated fields act on the flow to force interaction between equatorially symmetric and antisymmetric components that results in north-south asymmetric helicity. This symmetry-breaking magnetic feedback causes the flow to generate and maintain Mercury’s axially offset dipolar field..
2. T. Nakagawa, M. N. Nishino, H. Tsunakawa, F. Takahashi, H. Shibuya, H. Shimizu, M. Matsushima, Y. Saito, Electromagnetic ion cyclotron waves detected by Kaguya and Geotail in the Earth’s magnetotail, J. Geophys. Res. Space Physics, doi:10.1002/2017JA024505, 123, 1146-1164, 2018.03.
3. M. Nishino, Y. Harada, Y. Saito, H. Tsunakawa, F. Takahashi, S. Yokota, M. Matsushima, H. Shibuya, H. Shimizu, Kaguya observations of the lunar wake in the terrestrial foreshock: Surface potential change by bow-shock reflected ions, Icarus, doi:10.1016/j.icarus.2017.04.005, 293, 45-51, 2017.04.
4. Hiroaki Matsui, Eric Heien, Julien Aubert, Jonathan M. Aurnou, Margaret Avery, Ben Brown,Bruce A. Buffett, Friedrich Busse, Ulrich R. Christensen, Christopher J. Davies, Nicholas Featherstone, Thomas Gastine, Gary A. Glatzmaier, David Gubbins, Jean-Luc Guermond,Yoshi-Yuki Hayashi, Rainer Hollerbach, Lorraine J. Hwang, Andrew Jackson, Chris A. Jones,Weiyuan Jiang, Louise H. Kellogg, Weijia Kuang, Maylis Landeau, Philippe Marti, Peter Olson, Adolfo Ribeiro, Youhei Sasaki, Nathanaël Schaeffer, Radostin D. Simitev, Andrey Sheyko, Luis Silva, Sabine Stanley, Futoshi Takahashi, Shin-ichi Takehiro, Johannes Wicht,Ashley P. Willis, Performance benchmarks for a next generation numerical dynamo model, Geochem. Geophys. Geosyst., doi:10.1002/2015GC006159, 17, 2016.02.
5. H. Tsunakawa, F. Takahashi,H. Shimizu, H. Shibuya, M. Matsushima, Surface vector mapping of magnetic anomalies over the Moon using Kaguya and Lunar Prospector observations, J. Geophys. Res. Planets, doi:10.1002/2014JE004785, 120, 1160-1185, 2015.05.
6. M. N. Nishino, Y. Saito, H. Tsunakawa, Futoshi Takahashi, M. Fujimoto, Y. Harada, S. Yokota, M. Matsushima, H. Shibuya, H. Shimizu, Electrons on closed field lines of lunar crustal fields in the solar wind wake, Icarus, 10.1016/j.icarus.2014.12.007, 250, 238-248, 2015.04.
7. T. Nakagawa, T. Nakashima, T. Wada, H. Tsunakawa, Futoshi Takahashi, H. Shibuya, H. Shimizu, M. Matsushima, Y. Saito, ELF magnetic fluctuations detected by Kaguya in deepest lunar wake associated with type-II protons, Earth, Planets and Space, 10.1186/s40623-015-0196-0, 67, 50, 2015.04.
8. Y. Tsugawa, Y. Kato, N. Terada, H. Tsunakawa, Futoshi Takahashi, H. Shibuya, H. Shimizu, M. Matsushima, Harmonics of whistler-mode waves near the Moon, Earth, Planets and Space, 10.1186/s40623-015-0203-5, 67, 36, 2015.03.
9. Y. Saito, M. N. Nishino, S. Yokota, H. Tsunakawa, M. Matsushima, Futoshi Takahashi, H. Shibuya, H. Shimizu, Night side lunar surface potential in the Earth’s magnetosphere, Advances in Space Research, 10.1016/j.asr.2013.05.011, 54, 10, 1985-1992, 2014.11.
10. Futoshi Takahashi, Testing a toroidal magnetic field imaging method at the core-mantle boundary using a numerical dynamo model, Earth, Planets and Space, 10.1186/s40623-014-0157-z, 66, 157, 2014.11.
11. Futoshi Takahashi, Hideo Tsunakawa, Hisayoshi Shimizu, Hidetoshi Shibuya, Masaki Matsushima, Reorientation of the early lunar pole, NATURE GEOSCIENCE, 10.1038/NGEO2150, 7, 6, 409-412, 2014.06, 月がかつて地球と同じようなコアのダイナモによる双極子型のグローバル磁場を持っていたかどうかは、月の起源や進化史を理解するうえで不可欠な情報である。本研究では周回衛星から得られた月地殻磁場のデータを解析することにより、月にかつてコアのダイナモによって双極子磁場が存在していたこと、そしてそれが逆転を起こしていたことを示し、更に、月が極移動を経験していたことを明らかにした。.
12. S. Yokota, T. Tanaka, Y. Saito, K. Asamura, M. N. Nishino, M. Fujimoto, H. Tsunakawa, H. Shibuya, M. Matsushima, H. Shimizu, Futoshi Takahashi, Structure of the ionized lunar sodium and potassium exosphere: Dawn-dusk asymmetry, Journal of Geophysical Research: Planets, 10.1002/2013JE004529, 119, 4, 798-809, 2014.04.
13. Y. Tsugawa, Y. Kato, N. Terada, T. Ono, H. Tsunakawa, Futoshi Takahashi, H. Shibuya, H. Shimizu, M. Matsushima, Group-standing of whistler-mode waves near the Moon, Journal of Geophysical Research: Space Physics, 10.1002/2013JA019585, 119, 4, 2634-2648, 2014.04.