2月2日（火）13：00～16：00 Progress Report Defense zoom
Feb 2 Tue
2月2日（火）13：30～15：00 太陽系小天体セミナー zoom
Feb 2 Tue Solar System Minor Body Seminar
2月3日（水）13：30～15：00 NAOJ Science Colloquium zoom
Feb 3 Wed
2月3日（水）15：00～16：00 ALMA-J seminar zoom
Feb 3 Wed
詳細は以下をご覧下さい。
2月2日(火）
- Campus
- Online (Zoom)
- Seminar
- Progress Report Defense
- Regularly Scheduled/Sporadic
- Date and time
- February 2nd , 2021 13:00-16:00
- Speaker 1
- Yui Kasagi
- Affiliation
- SOKENDAI M2
- Title
- 高分散分光観測による地球型惑星探査および惑星形成過程の研究
- Speaker 2
- Raiga Kashiwagi
- Affiliation
- SOKENDAI M2
- Title
- 磁場に貫かれたフィラメント状分子雲の静水圧平衡状態における温度勾配の影響
- Speaker 3
- Takaho Masai
- Affiliation
- SOKENDAI M2
- Title
- Investigation on Aperture Efficiency Degradation Due to Aberrations in
(Sub)mm-wave Telescopes Towards High-Performance Multibeam Heterodyne-Receiver Optics Designs - Facilitator
- -Name：Matsuda, Graduate Student Affairs Unit
Sporadic
2月2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
- 2月2日（火曜日）13時30分～15時
- 場所
- zoom
- 講演者
- Evgenij Zubko
- 所属
- Kyung Hee University/ PERC, Chiba Institute of Technology
- タイトル
- Polarimetry of Comets with a Small Telescope
- Abstract
- During 2018-2020, our team measured the degree of linear polarization in a dozen comets using 22-cm and 50-cm telescopes located at the Ussuriysk Astrophysical Observatory (code C15; Russia). We will review polarization in four of those comets and provide insights into microphysics of their dust that is based on a highly realistic modeling of light scattering by cometary dust particles. In particular, we will address to Comet C/2018 V1 (Machholz-Fujikawa-Iwamoto), producing an extremely low positive polarization at side scattering; Comet 21P/Giacobini-Zinner that revealed fast and noticeable variations of its positive polarization; Comet C/2019 Y4 (ATLAS) whose polarization we were lucky to measure prior and after its disintegration in early April of 2020; and Comet 46P/Wirtanen whose polarization we monitored over two months in the 2018/2019 apparition.
- 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
2月3日（水）
- Campus
- Mitaka
- Seminar
- NAOJ Science Colloquium
- Regularly Scheduled/Sporadic
- Every Wednesday
- Date
- 2021 February 3
- Time
- 13:30-15:00
- Place
- Zoom
- Speaker
- Yuta Yamazaki (U. of Tokyo, *Student talk)
- Title
- Isotopic abundance of heavy elements and Galactic chemical evolution
- Abstract
-
The origin of heavy elements in the universe is one of the most important problem in this century. In this talk, I demonstrate how isotopic abundances are theoretically significant in studying the evolution of heavy elements.
Astronomical observations indicate that galactic stars have similar elemental abundance patterns. Its ‘universality’ has been considered as a clue of the existence of one dominant r-process site as r-process is the only powerful primary process and influential since the early galaxy. However, recent calculations suggest that different r-process astrophysical sites, such as supernovae or neutron star mergers, can produce similar ELEMENTAL abundance patterns while their ISOTOPIC abundance patterns differ. We performed galactic chemical evolution (GCE) simulations considering multiple r-process sites and reveal how the r-process isotopic abundance pattern has changed while keeping the similar elemental abundance pattern.
I will also present very recent results of the evolution of p-nuclides. Dominant nucleosyntheses including r-process are neutron capture processes which can not produce proton rich isotopes. Thus, other processes are required to explain the existence of such nuclides. Recent studies suggest that vp process is a possible solution. We performed GCE calculation for some p-isotopes and show their effects on the evolution of observable elemental abundances. - Facilitator
- -Name：Akimasa Kataoka
2月3日(水）
- Campus
- Mitaka
- Seminar
- ALMA-J seminar
- Regularly Scheduled/Sporadic
- Every Wednesday
- Date and Time
- 2021 Feb. 3 15:00-16:00
- Place
- Zoom
- Speaker
- Yuhei Iwata (Keio University)
- Title
- Time Variations in the Flux Density of Sgr A*
- Abstract
-
Sgr A*, the nucleus of our Galaxy, is one of the most convincing candidates for a supermassive black hole (SMBH) with a mass of ~4×10^6 Msun. It shows short-term variabilities and flaring activities in millimeter-wave, infrared, and X-ray bands. These flux variations are considered to be associated with accretion processes close to the SMBH. Here, I present the detection of time variations of the Sgr A* flux at 230 GHz with the ALMA cycle
5 observations. Measuring the flux density of Sgr A* in the snapshots of a ~1 min integration time, ten light curves with a 70 min duration were obtained. The light curves clearly show time variations with a time scale of a few tens of minutes, which is as short as the orbital period of the innermost stable circular orbit around a black hole with 4×10^6 Msun. Therefore, the observed millimeter emission is considered to have been occurred very close to the Galactic center black hole. - Facilitator
- Hiroshi Nagai, Xing Lu