PPARCセミナー (2025/10/24)
PPARCセミナー (2025/10/24)
(1)
[Name]
Chizuru Nose
[Title]
Influence of the solar wind on the hydrogen airglow in the Venusian upper atmosphere observed by Hisaki and VEX
[Abstract]
One of the big questions for Venus is whether or not Venus had an Ocean in the past. While Venusian current atmosphere is extremely dry, isotopic measurements of the D/H ratio suggest that Venus likely retained significant amounts of water in its past. Observations of hydrogen and oxygen in Venusian upper atmosphere can provide constraints on these processes. Results from Venus Express have shown the presence of hot and cold components in the Venusian hydrogen corona at different scale heights. It was suggested that charge exchange between the cold component and ionospheric or solar wind protons play a significant role in producing the hot component (Chaufray et al. 2012).Observations from Hisaki have shown that, when the high-speed solar wind originating from a corotating interaction region (CIR), arrived, the hydrogen column density derived from Ly-α increased by approximately 10% over a few days and then remained almost constant for weeks. The column density derived from Ly-β almost constant during this period. One possible explanation for the ~10% variations in Ly-α and the relatively stable Ly-β is an increased high-altitude hot hydrogen abundance due to interaction between the Venusian upper atmosphere and the high speed solar wind. However, since the Hisaki observations measured the globally averaged hydrogen column density, they could not resolve altitude-dependent variations.
In this seminar, I am going to share about my M Thesis plan and future study.
(2)
[Name]
Takeshi Sakanoi
[Title]
FACTORS衛星搭載紫外カメラの現状
[Abstract]
FACTORSはJAXA/ISASに提案することが検討されている複数衛星の編隊飛行ミッションである。本ミッションでは主にオーロラの微細構造と大気散逸のメカニズムの解明を目指す。我々は、この衛星に可視と紫外の2波長カメラが搭載することを検討している。可視カメラ（VISAI）は、科学用CMOSを用いて、N₂1PG線などのオーロラ発光を、高時間分解能（約0.1秒）かつ高空間分解能（約1km）で撮像し、小規模オーロラ構造の解明を行う。遠紫外線カメラ（FUVI）は、対物ミラーを採用し、可視カメラより広域をカバーする。FUVIの特徴は、日照領域でもオーロラ観測が可能なことである。本セミナーでは主にFUVIの科学目的と開発の現状について報告する。
