宇宙科学研究所 研究者総覧 「あいさすmap」

長谷川 洋

ハセガワ ヒロシ  (Hiroshi Hasegawa)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 助教

J-GLOBAL ID
200901040603353226
Researcher ID
A-1192-2007
researchmap会員ID
6000000662

外部リンク

論文

 163
  • H. Hasegawa, R. E. Denton, L.‐J. Chen, Q. Hu, M. N. Nishino, K.‐J. Hwang
    Journal of Geophysical Research: Space Physics 129(12) 2024年12月4日  査読有り
    Abstract We present observations on 24 April 2023 by the Magnetospheric Multiscale spacecraft at the dayside, mid‐latitude magnetopause, when an interplanetary magnetic cloud (MC) with sub‐Alfvénic flows and northward and dawnward interplanetary magnetic field components impacted Earth's magnetosphere. The aim is to reveal the processes of solar wind‐magnetosphere interaction under sub‐Alfvénic solar wind with northward magnetic field. Our analysis of electron and ion data suggests that magnetopause reconnection occurred near both polar cusps, forming boundary layers on closed magnetic field lines on both the solar wind (i.e., MC) and magnetospheric sides of the magnetopause. Grad‐Shafranov, electron‐magnetohydrodynamics, and polynomial reconstructions of magnetopause current layers show that local (equator‐of‐the‐cusp) reconnection occurred in a sub‐ion‐scale magnetopause current sheet with a low magnetic shear angle (30°). Interestingly, the local reconnection was observed between the two (MC‐side and magnetosphere‐side) layers of closed field lines. It indicates that reconnected field lines from double cusp reconnection were interacting to induce another reconnection at the mid‐latitude magnetopause. Our results suggest that magnetopause reconnection was more efficient or frequent under sub‐Alfvénic solar wind with much lower beta plasma conditions than typical conditions. We discuss the role of such efficient reconnection in the formation of low‐latitude boundary layers.
  • J. E. Stawarz, P. A. Muñoz, N. Bessho, R. Bandyopadhyay, T. K. M. Nakamura, S. Eriksson, D. B. Graham, J. Büchner, A. Chasapis, J. F. Drake, M. A. Shay, R. E. Ergun, H. Hasegawa, Yu. V. Khotyaintsev, M. Swisdak, F. D. Wilder
    Space Science Reviews 220(8) 2024年11月25日  査読有り
    Abstract Alongside magnetic reconnection, turbulence is another fundamental nonlinear plasma phenomenon that plays a key role in energy transport and conversion in space and astrophysical plasmas. From a numerical, theoretical, and observational point of view there is a long history of exploring the interplay between these two phenomena in space plasma environments; however, recent high-resolution, multi-spacecraft observations have ushered in a new era of understanding this complex topic. The interplay between reconnection and turbulence is both complex and multifaceted, and can be viewed through a number of different interrelated lenses - including turbulence acting to generate current sheets that undergo magnetic reconnection (turbulence-driven reconnection), magnetic reconnection driving turbulent dynamics in an environment (reconnection-driven turbulence) or acting as an intermediate step in the excitation of turbulence, and the random diffusive/dispersive nature of the magnetic field lines embedded in turbulent fluctuations enabling so-called stochastic reconnection. In this paper, we review the current state of knowledge on these different facets of the interplay between turbulence and reconnection in the context of collisionless plasmas, such as those found in many near-Earth astrophysical environments, from a theoretical, numerical, and observational perspective. Particular focus is given to several key regions in Earth’s magnetosphere – namely, Earth’s magnetosheath, magnetotail, and Kelvin-Helmholtz vortices on the magnetopause flanks – where NASA’s Magnetospheric Multiscale mission has been providing new insights into the topic.
  • K. A. Blasl, A. Settino, R. Nakamura, H. Hasegawa, T. K. M. Nakamura, M. Hosner
    Journal of Geophysical Research: Space Physics 129(11) 2024年11月15日  査読有り
    Abstract We examine characteristics of the boundaries of 11 Kelvin‐Helmholtz vortex crossings observed by MMS on 23 September 2017 under southward IMF conditions. At both the leading and trailing edges, boundary regions of mixed plasma are observed together with lower‐hybrid wave activity. We found that thicker boundary regions feature a higher number of sub‐ion scale current sheets, of which only one shows clear reconnection signatures. Moreover, the lower‐hybrid waves along the vortex spine region are identified as an effective mechanism for plasma transport with an estimated diffusion coefficient of s. Comparisons with 3D simulations performed under the same conditions as the MMS event suggest that the extension of the boundary regions as well as the number of current sheets are related to different evolutionary stages of the vortices. Such observations can be explained by changes in the upstream magnetic field conditions.
  • H. Hasegawa, M. R. Argall, N. Aunai, R. Bandyopadhyay, N. Bessho, I. J. Cohen, R. E. Denton, J. C. Dorelli, J. Egedal, S. A. Fuselier, P. Garnier, V. Génot, D. B. Graham, K. J. Hwang, Y. V. Khotyaintsev, D. B. Korovinskiy, B. Lavraud, Q. Lenouvel, T. C. Li, Y.-H. Liu, B. Michotte de Welle, T. K. M. Nakamura, D. S. Payne, S. M. Petrinec, Y. Qi, A. C. Rager, P. H. Reiff, J. M. Schroeder, J. R. Shuster, M. I. Sitnov, G. K. Stephens, M. Swisdak, A. M. Tian, R. B. Torbert, K. J. Trattner, S. Zenitani
    Space Science Reviews 220(6) 2024年9月2日  査読有り筆頭著者責任著者
    Abstract There is ample evidence for magnetic reconnection in the solar system, but it is a nontrivial task to visualize, to determine the proper approaches and frames to study, and in turn to elucidate the physical processes at work in reconnection regions from in-situ measurements of plasma particles and electromagnetic fields. Here an overview is given of a variety of single- and multi-spacecraft data analysis techniques that are key to revealing the context of in-situ observations of magnetic reconnection in space and for detecting and analyzing the diffusion regions where ions and/or electrons are demagnetized. We focus on recent advances in the era of the Magnetospheric Multiscale mission, which has made electron-scale, multi-point measurements of magnetic reconnection in and around Earth’s magnetosphere.
  • Abraham Chian, Rodrigo Miranda, Cesar Bertucci, Xóchitl Blanco-Cano, Joe Borovsky, Sergio Dasso, Ezequiel Echer, Adriane Franco, Kirolosse M. Girgis, J. Americo Gonzalez-Esparza, Tohru Hada, Hiroshi Hasegawa, Syau-Yun Hsieh, Primoz Kajdič, Christian Mazelle, Erico Rempel, Diana Rojas-Castillo, Beatriz Sanchez-Cano, David Sibeck, Marina Stepanova, José Valdés-Galicia, Juan Valdivia
    Journal of Atmospheric and Solar-Terrestrial Physics 106253-106253 2024年5月  査読有り

MISC

 25

書籍等出版物

 2

講演・口頭発表等

 128

所属学協会

 1

共同研究・競争的資金等の研究課題

 7