10月3日（月）13：30～15：00 太陽系小天体セミナー 南棟２階会議室
Oct 3 mon Solar System Minor Body Seminar Conference Room, South Bldg.2F
10月5日（水）13：30～14：30 理論コロキウム コスモス会館会議室
Oct 5 wed DTA colloquium Conference Room, Cosmos Lodge
10月7日（金）10：00～12：00 RISE臨時セミナー 輪講室
Oct 7 fri RISE special seminar Rinkoh Seminar Room
10月7日（金）13：30～15：00 太陽天体プラズマセミナー 院生セミナー室
Oct 7 fri Solar and Space Plasma Seminar Student Seminar Room, Subaru Bldg.
詳細は以下をご覧下さい。
10月3日（月）
- 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3日（月曜日）13時30分～15時
- 場所
- 南棟２階会議室
- 講演者
- 佐藤幹哉
- 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5日（水）
- Campus
- Mitaka
- Seminar
- DTA colloquium
- Regularly Scheduled/Sporadic
- Regularly Scheduled Date and time：5 October 2016, 13:30-14:30
- Place
- Conference Room, Cosmos Lodge
- Speaker
- Toshio Fukushima
- Affiliation
- NAOJ
- Title
- Numerical integration of gravitational field for general three-dimensional objects and its application to gravitational study of grand design spiral arm structure
- Abstract
- We present a method to integrate the gravitational field for general three-dimensional objects. By adopting the spherical polar coordinates centered at the evaluation point as the integration variables, we numerically compute the volume integral representation of the gravitational potential and of the acceleration vector. The variable transformation completely removes the algebraic singularities of the original integrals. The comparison with exact solutions reveals around 15 digits accuracy of the new method. Meanwhile, the 6 digit accuracy of the integrated gravitational field is realized by around $10^6$ evaluations of the integrand per evaluation point, which costs at most a few seconds at a PC with Intel Core i7-4600U CPU running at 2.10 GHz clock. By using the new method, we show the gravitational field of a grand design spiral arm structure as an example. The computed gravitational field shows not only spiral shaped details but also a global feature composed of a thick oblate spheroid and a thin disc. The developed method is directly applicable to the electromagnetic field computation by means of Coulomb’s law, the Biot-Savart law, and their retarded extensions. Sample {\sc fortran} 90 programs and test results are electronically available. (Ref. T. Fukushima 2016, MNRAS, doi:10.1093/mnras/stw2078) Facilitator
-Name：Tomoya Takiwaki - Comment
- in English
10月7日（金）
- キャンパス
- 三鷹
- セミナー名
- RISE臨時セミナー
- 定例・臨時の別
- 臨時
- 日時
- 10月7日（金曜日）10時～12時
- 場所
- 輪講室
- 講演者
- 飯野孝浩
- 所属
- 東京農工大学科学博物館
- タイトル
- Spatially Resolved Sub-millimeter Spectroscopy of Neptune’s Stratosphere with ALMA
- Abstract
- (optional)
- 連絡先
- -名前：野田寛大
- 備考
- 日本語、水沢RISE会議室とTV会議接続
10月7日（金）
- Campus
- Mitaka
- Seminar
- Solar and Space Plasma Seminar
- Regularly Scheduled/Sporadic
- Regular
- Date and time
- 7 October (Fri), 13:30-15:00
- Place
- Student Seminar Room, Subaru Bldg.
- Speaker
- Rodion Stepanov
- Affiliation
- Institute of Continuous Media Mechanics, Perm State University
- Title
- Magnetic and cross helicity cascades in MHD turbulence
- Abstract
-
Magnetohydrodynamic (MHD) turbulence is characterized by nonlinear interactions among fluctuations of the magnetic field and flow velocity over a range of spatial and temporal scales. It is ubiquitous in astrophysical plasmas and plays an important role in physical processes like plasma heating, the transport of energetic particles, and radiative transfer. The solar wind and the diffuse interstellar medium (ISM) are both examples that exhibit turbulent behavior, as evidenced by the power spectra determined from radio propagation observations. Also MHD turbulence is at the heart of the dynamo action generating magnetic fields in planets, stars and galaxies. The talk deals with the phenomenological description of the energy and helicities spectra under different conditions, i.e. global rotation or applied magnetic field.
These theoretical predictions are compared with results of the numerical simulations using the shell models of MHD turbulence. - Facilitator
- -Name：Shin Toriumi
- Comment
以上