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
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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.  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.
Abstract: Chemical composition around young stellar objects (YSOs) is an essential tool to investigate physical conditions and the history of star formation. Approximately 300 molecules have been detected in the interstellar medium so far. Some of them are categorized into complex organic molecules (COMs), and others are called carbon-chain molecules, which account for ~40% of the interstellar molecules. In this talk, I will present our recent work on chemistry on COMs and carbon-chain species around massive YSOs using ALMA. One topic is a study to investigate the formation processes of NH2CHO, a possible prebiotic molecule, using the ALMA Band 6 data toward 30 high-mass star-forming regions called the DIHCA project. Another topic is research to investigate chemical differentiation among carbon-chain species and nitrogen- and oxygen-bearing COMs using ALMA Band 3 data. We have proposed new carbon-chain chemistry around massive YSOs which we name Hot Carbon-Chain Chemistry (HCCC).
|403||2023年6月8日(木)||今井正尭 (国立天文台・科学研究部)||Observations of planetary-scale waves on Venus atmosphere||S. Koyama|
|404||2023年6月29日(木)||谷口琴美 (国立天文台・科学研究部)||Chemical complexity around massive young stellar objects revealed by ALMA||TBA|
|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|