Updated on 2026/04/27

写真a

 
MASUNAGA Kei
 
Title
Lecturer

Research Areas

  • Natural Science / Space and planetary sciences

Graduating School

  • Tohoku University, Faculty of Science, Department of Geophysics

    2009.03, Graduated

Graduate School

  • Tohoku University, Graduate School, Division of Natural Science, Department of Geophysics

    Master's Course, 2011.03, Completed

  • Tohoku University, Graduate School, Division of Natural Science

    Doctor's Course, 2014.03, Completed

Degree

  • PhD, Tohoku University, 2014.03

  • M. S., Tohoku University, 2011.03

  • B. S., Tohoku University, 2009.03

External Career

  • Nagoya University, JSPS Research Fellowship (PD), 2014.04 - 2015.12

  • University of Tokyo, JSPS Research Fellowship, 2016.01 - 2017.03

  • Swedish Institute of Space Physics, Postdoctoral researcher, 2017.04 - 2019.02

  • University of Colorado Boulder, JSPS Overseas Research Fellowship, 2019.02 - 2021.05

  • Japan Aerospace Exploration Agency, 2021.04 - 2024.03

  • , Part-time Lecturer, 2021.05 - 2023.03

  • Tohoku University, Guest researcher, 2024.04 -

  • Yamagata University, Lecturer, 2024.04 -

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Academic Society Affiliations

  • JpGU

  • SGEPSS

 

Papers

  • Contribution of multiple scattering to the distribution of Lyman alpha emission in comet comae, Icarus, 441 , 2025.11

    Yudai Suzuki, Kazuo Yoshioka, Kei Masunaga, Hideyo Kawakita, Yoshiharu Shinnaka, Go Murakami, Tomoki Kimura, Fuminori Tsuchiya, Atsushi Yamazaki, Ichiro Yoshikawa

    Single Author

  • Contribution of multiple scattering to the Lyman alpha radiance distribution in cometary comae, ICARUS, 441 , 2025.11

    Suzuki, Y; Yoshioka, K; Masunaga, K; Kawakita, H; Shinnaka, Y; Murakami, G; Kimura, T; Tsuchiya, F; Yamazaki, A; Yoshikawa, I

    Single Author

  • Magnetic field experiment at Phobos and in space around Mars by the Martian Moons eXploration (MMX) mission, PROGRESS IN EARTH AND PLANETARY SCIENCE, 12(1) , 2025.08

    Matsuoka, A; Yokota, S; Murata, N; Harada, Y; Imajo, S; Terada, N; Keika, K; Masunaga, K; Sakai, S; Nakagawa, H; Asamura, K; Kasahara, S; Saito, Y

    Single Author

  • Pre-flight performance of the ion energy mass spectrum analyzer for the Martian Moons eXploration (MMX) mission, PROGRESS IN EARTH AND PLANETARY SCIENCE, 12(1) , 2025

    Yokota, S; Matsuoka, A; Murata, N; Saito, Y; Asamura, K; Kasahara, S; Delcourt, D; Hadid, LZ; Terada, N; Keika, K; Harada, Y; Nakagawa, H; Masunaga, K; Sakai, S; Futaana, Y; Imajo, S; Seki, K; Nishino...

    Single Author

  • C<SUP>+</SUP> 133.5 nm Emission Mechanisms on Mars Revealed by the MAVEN Observations, ASTROPHYSICAL JOURNAL, 977(2) 226, 2024.12

    Sakai, S; Nakagawa, H; Deighan, J; Jain, SK; Masunaga, K; Tsuchiya, F; Terada, N; Mayyasi, M; Schneider, NM; Mitchell, DL; Mazelle, C; Benna, M; Lillis, RJ; Murakami, G; Curry, SM; Seki, K

    Single Author

  • Overview of the LAPYUTA mission (Life-environmentology, Astronomy, and PlanetarY Ultraviolet Telescope Assembly), Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 18, 2024.08

    Fuminori Tsuchiya, Go Murakami, Atsushi Yamazaki, Shingo Kameda, Tomoki Kimura, Ryoichi Koga, Kei Masunaga, Shotaro Sakai, Masahiro Ikoma, Akifumi Nakayama, Masami Ouchi, Masaomi Tanaka, Shin Toriumi,...

    Single Author

  • A Technique for Retrieving the Exospheric Number Density Distribution from Pickup Ion Ring Distributions, PLANETARY SCIENCE JOURNAL, 5(8) 180, 2024.08

    Masunaga, K; Terada, N; Leblanc, F; Harada, Y; Hara, T; Sakai, S; Yokota, S; Seki, K; Yamazaki, A; McFadden, JP; Usui, T

    Single Author

  • On the Periodic Variation of the Ion Density in the Martian Dayside Ionosphere During the Regional Dust Storm in September 2016, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 129(4) , 2024.04

    Hara, T; Masunaga, K; Terada, N; Sakai, S; Osanai, T; Seki, K; Fowler, CM; Hanley, KG; McFadden, JP; Curry, SM

    Single Author

  • BepiColombo mission confirms stagnation region of Venus and reveals its large extent, NATURE COMMUNICATIONS, 13(1) , 2022.12

    Persson, M; Aizawa, S; André, N; Barabash, S; Saito, Y; Harada, Y; Heyner, D; Orsini, S; Fedorov, A; Mazelle, C; Futaana, Y; Hadid, LZ; Volwerk, M; Collinson, G; Sanchez-Cano, B; Barthe, A; Penou, E; ...

    Single Author

  • Alternate oscillations of Martian hydrogen and oxygen upper atmospheres during a major dust storm, NATURE COMMUNICATIONS, 13(1) , 2022.11

    Masunaga, K; Terada, N; Yoshida, N; Nakamura, Y; Kuroda, T; Yoshioka, K; Suzuki, Y; Nakagawa, H; Kimura, T; Tsuchiya, F; Murakami, G; Yamazaki, A; Usui, T; Yoshikawa, I

    Single Author

  • Reflectivity of Venus's Dayside Disk During the 2020 Observation Campaign: Outcomes and Future Perspectives, PLANETARY SCIENCE JOURNAL, 3(9) , 2022.09

    Lee, YJ; Muñoz, AG; Yamazaki, A; Quémerais, E; Mottola, S; Hellmich, S; Granzer, T; Bergond, G; Roth, M; Gallego-Cano, E; Chaufray, JY; Robidel, R; Murakami, G; Masunaga, K; Kaplan, M; Erece, O; Hueso...

    Single Author

  • In Situ Observation of Solar-flare-induced Proton Cyclotron Waves Upstream from Mars, ASTROPHYSICAL JOURNAL, 934(2) , 2022.08

    Lin, HB; Guo, JP; Masunaga, K; Seki, K; Mazelle, C; Zhao, D; Huang, H; Zhao, J; Wei, Y; Liu, LB

    Single Author

  • Seasonal and Dust-Related Variations in the Dayside Thermospheric and Ionospheric Compositions of Mars Observed by MAVEN/NGIMS, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 126(11) , 2021.11

    Yoshida, N; Terada, N; Nakagawa, H; Brain, DA; Sakai, S; Nakamura, Y; Benna, M; Masunaga, K

    Single Author

  • Flow directions of low-energy ions in and around the diamagnetic cavity of comet 67P, MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 507(4) 4900-4913, 2021.11

    Bergman, S; Wieser, GS; Wieser, M; Nilsson, H; Vigren, E; Beth, A; Masunaga, K; Eriksson, A

    Single Author

  • Global Venus-Solar Wind Coupling and Oxygen Ion Escape, GEOPHYSICAL RESEARCH LETTERS, 48(3) , 2021.02

    Persson, M; Futaana, Y; Ramstad, R; Schillings, A; Masunaga, K; Nilsson, H; Fedorov, A; Barabash, S

    Single Author

  • Martian Oxygen and Hydrogen Upper Atmospheres Responding to Solar and Dust Storm Drivers: Hisaki Space Telescope Observations, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 125(12) , 2020.12

    Masunaga, K; Yoshioka, K; Chaffin, MS; Deighan, J; Jain, SK; Schneider, NM; Kimura, T; Tsuchiya, F; Murakami, G; Yamazaki, A; Terada, N; Yoshikawa, I

    Single Author

  • fe: Extrapolation to the Early Solar System, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 125(3) , 2020.03

    Persson, M; Futaana, Y; Ramstad, R; Masunaga, K; Nilsson, H; Hamrin, M; Fedorov, A; Barabash, S

    Single Author

  • Vertical Coupling Between the Cloud-Level Atmosphere and the Thermosphere of Venus Inferred From the Simultaneous Observations by Hisaki and Akatsuki, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 125(3) , 2020.03

    Nara, Y; Imamura, T; Masunaga, K; Lee, YJ; Terada, N; Yoshioka, K; Yamazaki, A; Seki, K; Yoshikawa, I; Yamada, M; Watanabe, S

    Single Author

  • Flow pattern of accelerated cometary ions inside and outside the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko, ASTRONOMY & ASTROPHYSICS, 630 , 2019.09

    Masunaga, K; Nilsson, H; Behar, E; Wieser, GS; Wieser, M; Goetz, C

    Single Author

  • Effects of the solar wind and the solar EUV flux on O<SUP>+</SUP> escape rates from Venus, ICARUS, 321 379-387, 2019.03

    Masunaga, K; Futaana, Y; Persson, M; Barabash, S; Zhang, TL; Bong, ZJ; Fedorov, A

    Single Author

  • Statistical Study of Relations Between the Induced Magnetosphere, Ion Composition, and Pressure Balance Boundaries Around Mars Based On MAVEN Observations, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 122(9) 9723-9737, 2017.09

    Matsunaga, K; Seki, K; Brain, DA; Hara, T; Masunaga, K; Mcfadden, JP; Halekas, JS; Mitchell, DL; Mazelle, C; Espley, JR; Gruesbeck, J; Jakosky, BM

    Single Author

  • Dawn-dusk difference of periodic oxygen EUV dayglow variations at Venus observed by Hisaki, ICARUS, 292 102-110, 2017.08

    Masunaga, K; Seki, K; Terada, N; Tsuchiya, F; Kimura, T; Yoshioka, K; Murakami, G; Yamazaki, A; Tao, C; Leblanc, F; Yoshikawa, I

    Single Author

  • The Mars crustal magnetic field control of plasma boundary locations and atmospheric loss: MHD prediction and comparison with MAVEN, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 122(4) 4117-4137, 2017.04

    Fang, XH; Ma, YJ; Masunaga, K; Dong, YX; Brain, D; Halekas, J; Lillis, R; Jakosky, B; Connerney, J; Grebowsky, J; Dong, CF

    Single Author

  • Statistical analysis of the reflection of incident O<SUP>+</SUP> pickup ions at Mars: MAVEN observations, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 122(4) 4089-4101, 2017.04

    Masunaga, K; Seki, K; Brain, DA; Fang, X; Dong, Y; Jakosky, BM; McFadden, JP; Halekas, JS; Connerney, JEP; Mitchell, DL; Eparvier, FG

    Single Author

  • O<SUP>+</SUP> ion beams reflected below the Martian bow shock: MAVEN observations, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 121(4) 3093-3107, 2016.04

    Masunaga, K; Seki, K; Brain, DA; Fang, X; Dong, Y; Jakosky, BM; McFadden, JP; Halekas, JS; Connerney, JEP

    Single Author

  • Periodic variations of oxygen EUV dayglow in the upper atmosphere of Venus: Hisaki/EXCEED observations, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 120(12) 2037-2052, 2015.12

    Masunaga, K; Seki, K; Terada, N; Tsuchiya, F; Kimura, T; Yoshioka, K; Murakami, G; Yamazaki, A; Kagitani, M; Tao, C; Fedorov, A; Futaana, Y; Zhang, TL; Shiota, D; Leblanc, F; Chaufray, JY; Yoshikawa, ...

    Single Author

  • The extension of ionospheric holes into the tail of Venus, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 119(8) , 2014.08

    Collinson, GA; Fedorov, A; Futaana, Y; Masunaga, K; Hartle, R; Stenberg, G; Grebowsky, J; Holmström, M; Andre, N; Barabash, S; Zhang, TL

    Single Author

  • Inner heliosphere MHD modeling system applicable to space weather forecasting for the other planets, SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS, 12(4) 187-204, 2014.04

    Shiota, D; Kataoka, R; Miyoshi, Y; Hara, T; Tao, C; Masunaga, K; Futaana, Y; Terada, N

    Single Author

  • Dependence of O<SUP>+</SUP> escape rate from the Venusian upper atmosphere on IMF directions, GEOPHYSICAL RESEARCH LETTERS, 40(9) 1682-1685, 2013.05

    Masunaga, K; Futaana, Y; Stenberg, G; Barabash, S; Zhang, TL; Fedorov, A; Okano, S; Terada, N

    Single Author

  • O<SUP>+</SUP> outflow channels around Venus controlled by directions of the interplanetary magnetic field: Observations of high energy O<SUP>+</SUP> ions around the terminator, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 116 , 2011.09

    Masunaga, K; Futaana, Y; Yamauchi, M; Barabash, S; Zhang, TL; Fedorov, AO; Terada, N; Okano, S

    Single Author

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Review Papers

  • Overview of Mars and Venus Observations Made by Hisaki, 118(5) 271-276, 2025.04

  • 火星衛星探査計画MMXイオンエネルギー質量分析器MSAフライトモデルの開発状況, 宇宙科学技術連合講演会講演集(CD-ROM), 67th , 2023

    横田勝一郎, 松岡彩子, 原田裕己, 今城峻, 村田直史, 齋藤義文, 益永圭, 寺田直樹, 桂華邦裕

Grant-in-Aid for Scientific Research

  • Grant-in-Aid for Scientific Research(C)，2025.04 - 2029.03

  • Grant-in-Aid for Scientific Research(C)，2022.04 - 2025.03

  • Grant-in-Aid for Research Activity start-up，2021.04 - 2024.03

  • Grant-in-Aid for Special researchers encouragement expenses，2014.04 - 2017.03

  • Grant-in-Aid for Special researchers encouragement expenses，2012.04 - 2014.03