6月4日（火）13：30～15：00 太陽系小天体セミナー 南棟２階会議室
Jun 4 Tue Solar System Minor Body Seminar Conference Room, South Bldg.2F
6月5日（水）10:30～12:00 総研大コロキウム 講義室
Jun 5 Wed SOKENDAI colloquium Lecture Room
6月5日（水）13：30～15：00 科学研究部コロキウム 開発棟３号館３階会議室
Jun 5 Wed Colloquium of Division of Science Conference room, Instrument Development Bldg. 3 3F
6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
Jun 7 Fri Solar and Space Plasma Seminar Student Seminar Room, Subaru Bldg.
6月7日（金）16：00～17：00 国立天文台談話会 大セミナー室
Jun 7 Fri NAOJ Seminar Large Seminar Room
詳細は以下をご覧下さい。
6月4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
- 6月4日（火曜日）13時30分～15時
- 場所
- 南棟２階会議室
- 講演者
- 高橋葵
- 所属
- アストロバイオロジーセンター
- 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
6月5日（水）
- Campus
- Mitaka
- Seminar
- SOKENDAI colloquium
- Regularly Scheduled/Sporadic
- Regular
- Date and time
- June 5, 2019, 10:30 -12:00
- Place
- Lecture Room
- Speaker
- Hiroyuki Tako ISHIKAWA
- Affiliation
- SOKENDAI 4th year (D2) (Supervisor: Wako Aoki, Saeko Hayashi, Takayuki Kotani)
- Title
- Caveat in Detailed Chemical Analysis of early-M-dwarfs
Abstract(Option): We verified our chemical analysis method by the comparison between the chemical abundances of mid-M dwarfs (Teff ~
3200 K) we determined and those of FGK-type stars which constitute the binary systems with the mid-M dwarfs. However, we subsequently tried applying the same comparison to an early-M dwarf (Teff ~ 3700 K) and found that the error size of abundances become much larger in such temperature regime. We suspect that it is because the degrees of ionization of dominant metals change most drastically just around the temperature. We report the situation. - Speaker
- Jungha Kim
- Affiliation
- SOKENDAI 5th year (D3) (Supervisor: Mareki Honma, Katsunori Shibata, Tomoya Hirota)
- Title
- TBD
- Facilitator
- -Name： Kei Ito
- Comment
6月5日（水）
- キャンパス
- 三鷹
- セミナー名
- 科学研究部コロキウム
- 定例・臨時の別
- 定例
- 日時
- 6 月5 日（水曜日）13:30 ～ 15:00
- 場所
- 開発棟 3F 会議室
- 講演者
- Carol Kwok
- 所属
- 東京大学
- タイトル
- Planetesimal dynamics in the presence of a massive companion
- Abstract
- The standard models of planet formation explain well how planets form in axisymmetric, unperturbed disks in single star systems. However, it is possible that giant planets could have already formed before the runaway growth of planetary embryos. In other words, the early evolution of planetesimals can be affected by strong perturbations from the massive planets in the system, and thus deviate from the standard scenario. We aim to investigate the dynamics of planetesimals, including their orbital characteristics and evolution, in a system with the presence of a massive perturber to find out its impact on the formation of terrestrial planets or the core of giant planets. Currently, we are using N-body simulations to calculate the orbits of planetesimals under the influence of a planet with the mass of Jupiter and gas drag. In our next step, we will include size distribution as well as the self-gravity of planetesimals in our simulations.
- 連絡先
- -名前：Akimasa Kataoka
- 備考
- 使用する言語は英語、開発棟は土足厳禁ですので、入り口のスリッパをご利用ください。
6月7日（金）
- Campus
- Mitaka
- Seminar
- Solar and Space Plasma Seminar
- Regularly Scheduled/Sporadic
- Regular
- Date and time
- 7 June (Fri), 13:30-15:00
- Place
- Student Seminar Room, Subaru Bldg.
- Speaker
- Tomoko Kawate
- Affiliation
- ISAS/JAXA
- Title
- Infrequent Occurrence of Significant Linear Polarization in H-alpha Solar Flares
- Abstract
-
We performed statistical and event studies of linear polarization in the H-alpha line during solar flares. The statistical study revealed that, among 71 H-alpha flares analyzed, including 64 GOES flares, only one event shows significant linear polarization signals. Such an infrequent occurrence of significant linear polarization in solar flares is consistent with the result by Bianda et al. (2005), who studied 30 flares and found no polarization signals. In the event showing the significant polarization, the maximum degree of linear polarization was 1.16±0.06%, and the average direction of the polarization deviated by -142.5±6.0 degrees from the solar north. The observed polarization degrees and the directions are consistent with the preceding reports (e.g. Henoux et al. 1990; Emslie et al. 2000; Hanaoka et al. 2003). These strong linear polarization signals did not appear at major flare ribbons, nor did they correlate with either hard or soft X-ray emissions temporally
or spatially. Instead they appeared at a minor flare kernel, which corresponds to one of the footpoints of a coronal loop. The active region caused coronal dimming after the soft X-ray peak. The observed flare show no direct evidence that the linear polarization is produced by high energy particles, which are often considered to generate the polarization. On the other hand, our study suggests the possibility that coronal mass ejections, which have been often observed in flares showing linear polarization signals, play an important role for exciting linear polarization at H-alpha flare kernels. - Facilitator
- -Name：Masahito Kubo
- Comment
6月7日（金）
- Campus
- Mitaka
- Seminar
- NAOJ seminar
- Regularly Scheduled/Sporadic
- Scheduled
- Date and time
- Fri 7 Jun 16:00～17:00
- Place
- Large Seminar Room
- Speaker
- 高棹真介
- Affiliation
- 国立天文台フェロー
- Title
- 「原始星はどのように質量を獲得するのか：円盤降着の最内縁の理解に迫
る」 - Abstract
-
原始星は冷たい分子雲ガスの収縮によって形成され、できた頃の質量は太陽質量のたかだか1%程度しかない。
つまりほとんどの質量は星の周囲に取り残されているため、原始星への降着過程を解き明かすことは星形成における重要なテーマとなっている。
星に降着するガスは角運動量を持っているため、原始星への質量降着は円盤を通じたものになる。
すなわちこの円盤最内縁から原始星にガスがどう降着するのかを解き明かすことが必要だが、濃いガスに埋もれた原始星近傍を観測から調べることは
一般に困難であり、シミュレーションによるアプローチも無数の困難に阻まれ、これまでほとんど調べられてこなかった。
この現状を打開するべく、我々は原始星・円盤の３次元磁気流体モデルの構築を進めている。
その過程の中で、これまで太陽物理研究で議論されてきた星表面での爆発現象や、ブラックホール降着円盤の研究で注目されてきた
磁場の輸送といったものの重要性が徐々に明らかになってきた。本講演ではこれまでの理解を概観して問題点を整理し、我々の取り組みを紹介していく。 - Facilitator
- -Name：Kataoka, Akimasa