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タイトル: | Active auroral arc powered by accelerated electrons from very high altitudes |
著者: | Imajo, Shun https://orcid.org/0000-0002-9862-844X (unconfirmed) Miyoshi, Yoshizumi Kazama, Yoichi Asamura, Kazushi Shinohara, Iku Shiokawa, Kazuo Kasahara, Yoshiya Kasaba, Yasumasa Matsuoka, Ayako https://orcid.org/0000-0001-5777-9711 (unconfirmed) Wang, Shiang-Yu Tam, Sunny W. Y. Chang, Tzu‑Fang Wang, Bo‑Jhou Angelopoulos, Vassilis Jun, Chae-Woo Shoji, Masafumi Nakamura, Satoko Kitahara, Masahiro Teramoto, Mariko Kurita, Satoshi https://orcid.org/0000-0002-1553-9557 (unconfirmed) Hori, Tomoaki |
著者名の別形: | 今城, 峻 三好, 由純 風間, 洋一 浅村, 和史 篠原, 育 塩川, 和夫 笠原, 禎也 笠羽, 康正 松岡, 彩子 小路, 真史 中村, 紗都子 北原, 理弘 寺本, 万里子 栗田, 怜 堀, 智昭 |
キーワード: | Aurora Magnetospheric physics |
発行日: | 18-Jan-2021 |
出版者: | Springer Nature |
誌名: | Scientific Reports |
巻: | 11 |
論文番号: | 1610 |
抄録: | Bright, discrete, thin auroral arcs are a typical form of auroras in nightside polar regions. Their light is produced by magnetospheric electrons, accelerated downward to obtain energies of several kilo electron volts by a quasi-static electric field. These electrons collide with and excite thermosphere atoms to higher energy states at altitude of ~ 100 km; relaxation from these states produces the auroral light. The electric potential accelerating the aurora-producing electrons has been reported to lie immediately above the ionosphere, at a few altitudes of thousand kilometres1. However, the highest altitude at which the precipitating electron is accelerated by the parallel potential drop is still unclear. Here, we show that active auroral arcs are powered by electrons accelerated at altitudes reaching greater than 30, 000 km. We employ high-angular resolution electron observations achieved by the Arase satellite in the magnetosphere and optical observations of the aurora from a ground-based all-sky imager. Our observations of electron properties and dynamics resemble those of electron potential acceleration reported from low-altitude satellites except that the acceleration region is much higher than previously assumed. This shows that the dominant auroral acceleration region can extend far above a few thousand kilometres, well within the magnetospheric plasma proper, suggesting formation of the acceleration region by some unknown magnetospheric mechanisms. |
記述: | オーロラ粒子の加速領域が超高高度まで広がっていたことを解明 -オーロラ粒子の加速の定説を覆す発見-. 京都大学プレスリリース. 2021-01-20. |
著作権等: | © The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. |
URI: | http://hdl.handle.net/2433/261116 |
DOI(出版社版): | 10.1038/s41598-020-79665-5 |
PubMed ID: | 33462252 |
関連リンク: | https://www.kyoto-u.ac.jp/ja/research-news/2021-01-20-0 |
出現コレクション: | 学術雑誌掲載論文等 |
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