Oct 19 Tue 10:00～11:30 太陽系小天体セミナー / Solar System Minor Body Seminar zoom
Oct 20 Wed 15:30～17:00 NAOJ Science Colloquium zoom
Oct 22 Thu 13:00～14:30 Solar and Space Plasma Seminar zoom
詳細は以下をご覧下さい
10月19日（火）
キャンパス：三鷹
セミナー名：太陽系小天体セミナー
定例・臨時の別：定例
日時：10月19日（火曜日）10時00分～11時30分
場所：zoom
講演者：有松亘
世話人の連絡先
名前：渡部潤一
備考：テレビ会議またはスカイプによる参加も可
10月20日（水）
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2021 Oct 20, 15:30-17:00
Place：zoom / Instrument Development Bldg. 3 (hybrid)
Speaker: Masato Kobayashi
Affiliation：NAOJ
Title: Molecular cloud formation and evolution, linking the formation of individual stars to galactic-scale star formation
Abstract:
Star formation is one of the main drivers of galaxy evolution, and thus the understanding of star formation processes in various galactic environments is central of understanding the history of the Universe. Molecular clouds host star formation and are the key object to govern the star formation efficiency of galaxies. I will first summarize the current theoretical/observational understanding of molecular cloud formation and evolution. I will then show my numerical simulations to explore the evolution of the density/turbulent structure, to investigate how they control the star formation rate along molecular cloud formation. I will also briefly mention my future plans that I will be working on in NAOJ, which will eventually reveal the connection between the formation of individual stars and galactic-scale star formation, from both theoretical and observational perspectives.
Facilitator
-Name：Akimasa Kataoka
Comment：English
10月22日（金）
Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：22 October (Fri), 13:00-14:30
Place： zoom
Speaker：Takafumi Kaneko
Affiliation：Institute for Space-Earth Environmental Research, Nagoya University
Title: Impact of convective flows on sunspot formation and evolution
Abstract:
Huge solar flares occur in sunspots where a large amount of magnetic energy is stored. In observations, flare-productivity of sunspots is empirically associated with the area and the distribution of magnetic fields. However, what determines the features of flare-productive sunspots has not been revealed. The sunspot parameters are strongly affected by the magnetic fields in the convection zone and the convective flows. So far the dependency on the magnetic parameters in the convection zone has been intensively investigated; however, the dependency on the convective flows has been poorly understood. The aim of this study is to reveal the impact of convective flows on formation and evolution of the sunspot. We simulated transport of magnetic fields in the convection zone and formation of sunspots in the photosphere using radiative MHD simulation code R2D2. In the initial state, a magnetic flux rope was set inside the convection zone. We conducted parameter survey by changing the initial positions of the flux ropes in the same convective velocity field. 93 simulations were carried out using Fugaku supercomputer. As a result, various kinds of the sunspots were reproduced. The flare-productive sunspots consistent with the observations (delta-spots) were reproduced in many cases. In several cases, sunspots close to simple bipole (beta-spots) were reproduced. There were also the cases without flux emergence. We found good correlation between the distribution of magnetic free energy in the photosphere and the location of the strong downflow in the convection zone from -30 Mm to -100 Mm in depth. Our result suggests that convection has great impact on formation and evolution of the sunspots, and the features of the flare-productive sunspots were not always determined by the initial magnetic fields in the convection zone.
We also introduce an ongoing project to reproduce huge solar flare using the simulated sunspot magnetic fields and a new data-driven MHD method.
Facilitator
-Name：Yusuke Kawabata
Comment：in English,