Shotaro Sakai

Influence of the solar wind on the Venusian hydrogen upper atmosphere: SPICAV limb observations and radiative transfer modeling

Chizuru Nose, Kei Masunaga, Fuminori Tsuchiya, Shotaro Sakai et autres

Although Venus is often referred to as Earth's twin, its surface environment differs remarkably, with surface temperatures reaching approximately 700 K and no liquid water. The observed D/H ratio in the atmosphere suggests that Venus once possessed a substantial water inventory, and …

jp, fr (code pays fourni par la source)

Polar enhancement of lunar water ions observed by Kaguya: Implications for surface-exosphere coupling

Kei Masunaga, Shoichiro Yokota, Yuki Harada, Kunihiro Keika et autres

Water on the Moon is crucial for understanding its origin and evolution and is also of interest for future human exploration. Recent observations show that water ice and hydroxyl are mainly concentrated in permanently shadowed regions near the lunar poles, and these …

jp, us (code pays fourni par la source)

Electron-impact C I 156.1 nm emission as a probe of Martian ionospheric variability

Shotaro Sakai, Justin Deighan, Hiromu Nakagawa, Fuminori Tsuchiya et autres

It is widely believed that Mars had a warm and humid climate more than 4 billion years ago, as it maintained a thick atmosphere and sustained liquid water. In contrast, present-day Mars has only a thin atmosphere, and no liquid water remains …

jp, us, fr (code pays fourni par la source)

Simulation data supporting "Comparison of Titan's atmospheric escape processes driven by the Saturn and solar winds using 3D magnetohydrodynamic simulations"

Ryoma Takada, Tomoki Kimura, Shotaro Sakai, Yuki Maeda et autres

Simulation data supporting "Comparison of Titan's atmospheric escape processes driven by the Saturn and solar winds using 3D magnetohydrodynamic simulations"

Ryoma Takada, Tomoki Kimura, Shotaro Sakai, Yuki Maeda et autres

Effects of Hot Oxygen Corona on Ion Escape From Venus‐Like Planets

Tetsuo Nishioka, K. Seki, Ryoya Sakata, N. Terada et autres

Abstract Due to the lack of a significant planetary magnetic field, the upper atmospheres of Venus‐like planets interact directly with the stellar wind. Therefore, thermal atomic oxygen in the thermosphere and hot oxygen in the corona produced by non‐thermal processes in the …

jp (code pays fourni par la source)

Asymmetrically Distributed Kelvin‐Helmholtz Instability at Venusian Magnetosphere

Maodong Yan, Jiuhou Lei, N. Terada, Binzheng Zhang et autres

Abstract The asymmetric distribution of Kelvin‐Helmholtz (KH) instability at Venusian ionopause is investigated using a multifluid model. Results show that KH instability distributes asymmetrically, preferentially developing in the −E (anti‐parallel to the interplanetary electric field) hemisphere. In the magnetosheath, solar wind H …

cn, jp, hk, us (code pays fourni par la source)

Atmospheric Escape Rates from Mars - If it Orbited an Old M-Dwarf Star

David A. Brain, O. Cohen, T. E. Cravens, Kevin France et autres

Atmospheric escape is an important process that influences the evolution of planetary atmospheres. A variety of physical mechanisms can contribute to escape from an atmosphere, including thermal escape, ion escape, photochemical escape, and sputtering. Here we estimate escape rates via each of …

Atmospheric Escape Rates from Mars - If it Orbited an Old M-Dwarf Star

David A. Brain, Ofer Cohen, T. E. Cravens, Kevin France et autres

Atmospheric escape is an important process that influences the evolution of planetary atmospheres. A variety of physical mechanisms can contribute to escape from an atmosphere, including thermal escape, ion escape, photochemical escape, and sputtering. Here we estimate escape rates via each of …

us, fr, jp, de, se, fi, gb, in, nl (code pays fourni par la source)

Effects of Hot Oxygen Corona on Ion Escape from Venus-like Planets

Tomoaki Nishioka, Kanako Seki, Ryoya Sakata, Naoki Terada et autres

This dataset contains the simulation results in the paper "Effects of Hot Oxygen Corona on Ion Escape from Venus-like Planets" submitted to Journal of Geophysical Research: Space Physics.

jp (code pays fourni par la source)

Dawn–Dusk Asymmetry of the Io Plasma Torus Derived from Io’s Auroral Footprints Observed by Juno-UVS

Shinnosuke Satoh, Vincent Hue, Fuminori Tsuchiya, Shotaro Sakai et autres

Abstract The Io plasma torus (IPT) is a dense plasma cloud that corotates around Jupiter near Io’s orbit. A dawn-to-dusk electric field shifts the IPT dawnward. The shift orientation has been previously measured, but the observing geometries have limited our understanding of …

Effects of stellar XUV spectra on atmospheric escape from a Mars-like planet orbiting inactive low-mass stars

Shotaro Sakai, Akifumi Nakayama, K. Seki, N. Terada et autres

ABSTRACT The influence of stellar extreme ultraviolet (XUV) spectral shape on ion escape from Mars-like planets is investigated using a multispecies single-fluid magnetohydrodynamic model coupled with thermospheric profiles derived from a one-dimensional model under various XUV conditions. Target stars include the Sun, …

jp, us, fr (code pays fourni par la source)