Publications by authors named "Yoshifumi Futaana"

Article Synopsis
  • * When the angle between the solar wind’s velocity and its magnetic field is small, Mars experiences a unique induced magnetosphere that causes no shock on the day side and only weak shocks on the sides.
  • * Recent hybrid simulations with a small cone angle align with findings from Mars exploration missions, indicating that these complex induced magnetospheres could play a significant role in atmospheric loss, an area that needs further investigation.
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Mars lacks a global magnetic field, and instead possesses small-scale crustal magnetic fields, making its magnetic environment fundamentally different from intrinsic magnetospheres like those of Earth or Saturn. Here we report the discovery of magnetospheric ion drift patterns, typical of intrinsic magnetospheres, at Mars using measurements from Mars Atmosphere and Volatile EvolutioN mission. Specifically, we observe wedge-like dispersion structures of hydrogen ions exhibiting butterfly-shaped distributions (pitch angle peaks at 22.

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Mercury's magnetosphere is known to involve fundamental processes releasing particles and energy like at Earth due to the solar wind interaction. The resulting cycle is however much faster and involves acceleration, transport, loss, and recycling of plasma. Direct experimental evidence for the roles of electrons during this cycle is however missing.

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One of the grand challenges in heliophysics is the characterization of coronal mass ejection (CME) magnetic structure and evolution from eruption at the Sun through heliospheric propagation. At present, the main difficulties are related to the lack of direct measurements of the coronal magnetic fields and the lack of 3D in-situ measurements of the CME body in interplanetary space. Nevertheless, the evolution of a CME magnetic structure can be followed using a combination of multi-point remote-sensing observations and multi-spacecraft in-situ measurements as well as modeling.

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As an Earth-like planet Venus probably had a primordial dipole field for several million years after formation of the planet. Since this dipole field eventually vanished the ionosphere of Venus has been exposed to the solar wind. The solar wind is shocked near Venus, and then scavenges the ionospheric particles through the magnetosheath and the magnetotail.

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