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東京大学・天文学教育研究センターでは2003年4月から談話会を開いています。
第一線で活躍されている研究者の方々を講師にお招きし、最先端の研究成果をお話しいただきます。
講師の方には、大学院生の参加者のことも考慮し、レビュー的な側面も含めた上で、ご自身の研究紹介をお願いしています。
なお、当談話会は天文学研究者・学生を対象に大学・大学院での
専門的な研究と教育を目的として開催されています。
一般の方は公開講座・講演会などにご参加いただければ幸いです。
ML: semiadm _at_ ioa.s.u-tokyo.ac.jp
please replace _at_ with @
Language: Japanese
Abstract: The mystery of the fast-rotating atmosphere on Venus is well known as the name of the super-rotation. At the cloud top altitude of ~70 km, the super-rotation reaches 100 ms-1 and many types of atmospheric waves are found as periodical signals in winds and temperatures. Planetary-scale waves are one of the important clues that maintain the super-rotation by transporting angular momentum and heat. Imai et al. [2016] implemented long-term monitoring of the rotation period of planetary-scale UV features using a ground-based telescope. Two significant periodicities, at 5.1 and 3.5 days, should be manifestations of these planetary-scale waves (Rossby wave and Kelvin wave, respectively), which were subjected to temporal variations within several months. However, the temporal evolution of these variations remained largely unknown. On 7 December 2015, the Japanese Venus Climate Orbiter named Akatsuki successfully inserted the Venus orbit, and its exploration is still ongoing. The periodicities in the UV brightness and winds derived from cloud-tracking were analyzed throughout the entire observation, and dramatic evolutions of planetary-scale waves were revealed [Imai et al., 2019]. One of the prominent events was observed from June to October 2017, where a 5-day Rossby wave consisting of equatorially symmetric planetary-scale vortices with zonal wavenumber 1 had been captured. At the same time, planetary-scale temperature deviations associated with the 5-day wave were reconstructed for the first time from the Longwave Infrared Camera (LIR) images. By using cloud-tracked winds and brightness temperature measurements, angular momentum and heat fluxes induced by the 5-day wave were quantitatively estimated. While the origin of transient waves is still unclear, the poleward heat transport suggests that they can be related to upward propagating Rossby waves and/or baroclinic instability waves in the lower cloud layer. In this talk, I would like to introduce our research with the "history" of myself involved in planetary exploration missions based on my background in ground-based observations.
| # | Date | Speaker | Title | Chair |
| 404 | 2023年6月29日(木) | 谷口琴美 (国立天文台・科学研究部) | TBA | 天文センター |
詳細はこちら: 令和5(2023)年度談話会
| # | Date | Speaker | Title | Chair |
| 402 | 2023年5月25日(木) | Shinji Fujita (Institute of Astronomy, the University of Tokyo) | Distance determination of molecular clouds in the Galaxy using deep learning | M. Imai |
| 401 | 2023年4月20日(木) | Yao-Lun Yang (Research Scientist, RIKEN) | Complex chemistry in the era of JWST and ALMA | K. Kohno |
| 400 | 2023年4月6日(木) | Doug Johnstone (National Research Council Canada) | What the Variability of Embedded Protostars Tells Us about Accretion: Past, Present, and Future | K. Kohno |
