4月17日（月）13：30～14：30 理論コロキウム コスモス会館会議室
Apr 17 mon DTA colloquium Conference Room, Cosmos Lodge
4月18日（火）13：30～15：00 太陽系小天体セミナー 南棟２階会議室
Apr 18 tue Solar System Minor Body Seminar Conference Room, South Bldg.2F
4月19日（水）13：30～14：30 理論コロキウム コスモス会館会議室
Apr 19 wed DTA colloquium Conference Room, Cosmos Lodge
4月21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
Apr 21 fri Solar and Space Plasma Seminar Student Seminar Room, Subaru Bldg.
4月21日（金）16：00～17：00 国立天文台談話会 大セミナー室
Apr 21 fri NAOJ Seminar Large Seminar Room
詳細は以下をご覧下さい。
4月17日（月）
- Campus
- Mitaka
- Seminar
- DTA colloquium
- Date and time
- 17 April 2017, 13:30-14:30
- Place
- Conference Room, Cosmos Lodge
- Speaker
- Toshihiko Kawano
- Affiliation
- LANL/Tokyo Tech.
- Title
- beta-delayed neutron emission and fission for r-process nucleosynthesis
- Abstract
- (optional)
We give a brief summary of our recent development of nuclear reaction theories with a particular focus on nuclear data production for the r-process nucleosynthesis. The topics include calculations of the beta-delayed process for neutron-rich nuclei, where several neutrons can be emitted, and eventually fission may take place as well. Our recent studies on fission itself are also given. - Facilitator
- -Name：Tomoya Takiwaki
- Comment
- in English
4月18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
- 4月18日（火曜日）13時30分～15時
- 場所
- 南棟２階会議室
- 講演者
- 匠あさみ
- 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
4月19日（水）
- Campus
- Mitaka
- Seminar
- DTA colloquium
- Date and time
- 19 April 2017, 13:30-14:30
- Place
- Conference Room, Cosmos Lodge
- Speaker
- Masaki Yamaguchi
- Affiliation
- U. Tokyo
- Title
- The number of black hole-star binaries discovered by the astrometric satellite, Gaia
- Abstract
- (optional)
Although it is believed that there are 10^8-9 stellar mass black holes (BH) in Milky Way, until now only ~60 BHs have been discovered. Moreover, masses of only a dozen BHs of them are constrained. By discovering more BHs and estimating their masses, we would obtain the mass distribution of BHs with a higher confidence level. This distribution is expected to constrain a theoretical model of the supernova explosion in which a BH is produced as a remnant. Gaia is now operated and have a capability to detect binaries with an unseen companion, such as a BH or a neutron star. Gaia performs a high-precision astrometry with the optical band (0.3-1.0um), and surveys a whole sky, where main observational targets are stars. If a target star has an unseen companion, it should show an elliptical motion on the celestial sphere. Gaia can confirm the companion by detecting such motion. Moreover, this elliptical motion leads to all orbital elements, which enables us to estimate the mass of companion. If this mass is larger than 3 solar masses, we can confirm the companion as a BH. In my talk, I will show how many BHs can be detected by such method with Gaia. Considering the binary evolution, we obtain the number of detectable BHs, ~600, for main sequence targets. This means that Gaia can discover the order of one thousand BHs whose masses can be found, although we know only a dozen such BHs now. We conclude that the astrometric observation for binaries is very powerful method for finding BHs. - Facilitator
- -Name：Tomoya Takiwaki
- Comment
- in English
4月21日（金）
- Campus
- Mitaka
- Seminar
- Solar and Space Plasma Seminar
- Regularly Scheduled/Sporadic
- Regular
- Date and time
- 21 April (Fri), 13:30-15:00
- Place
- Student Seminar Room, Subaru Bldg.
- Speaker
- Yusuke Kawabata
- Affiliation
- Univ of Tokyo-ISAS/JAXA
- Title
- Non-potential field formation in the X-shaped quadrupole magnetic field configuration
- Abstract
-
Some types of solar flares are observed in X-shaped quadrupolar field configuration. For understanding the magnetic energy storage in such a region, we studied the non-potential field formation in an X-shaped quadrupolar field region formed in active region NOAA 11967, which produced three X-shaped M-class flares on 2 February 2014. Nonlinear force-free field (NLFFF) modeling was applied to the time series of vector magnetic field maps from Hinode SOT/SP and SDO/HMI.
Our analysis of temporal 3D magnetic field evolution shows that the sufficient free energy had already been stored more than 10 hours before the occurrence of the first M-class flare and that the storage was observed in the localized region, rather than in the entire X-shaped quadrupolar field. In the localized region, quasi-separatrix layers
(QSLs) started to develop gradually from 9 hours before the first M-class flare. One of the flare ribbons appeared in the first M-class flare was co-spatial with the location of the QSLs, suggesting that the formation of the QSLs is important in the process of energy release.
These QSLs do not appear in the potential field calculation, suggesting that the non-potential field created these QSLs. The QSLs were formed associated with the transverse photospheric motion of the pre-emerged flux and the emergence of a new flux. This observation indicates that the occurrence of the flares needs the formation of QSLs in the non-potential field where the free magnetic energy is stored in advance. - Facilitator
- -Name：Shin Toriumi
4月21日（金）
- キャンパス
- 三鷹
- セミナー名
- 国立天文台談話会
- 定例・臨時の別
- 定例
- 日時
- 4月21日（金） 16:00-17:00
- 場所
- 大セミナー室
- 講演者
- Paola Caselli
- 所属
- Max-Planck-Institut fur extraterrestrische Physik
- タイトル
- Astrochemistry at the dawn of star and planet formation
- Abstract
- Stars and stellar systems in our Galaxy form within dense (~100,000 H2 molecules per cc) and cold (~10 K) fragments of interstellar molecular clouds, called pre-stellar cores. Important chemical processes take place at this early stage, such as isotope fractionation, production of complex organic molecules and growth of thick icy mantles onto dust grains, where water and organics are stored. These processes can affect later phases of star and planet formation. Molecules are unique tracers of the dynamical and chemical evolution of star and planet forming regions. Thus, astrochemistry is crucial to test theories and shed light on our origins. In this talk I shall review the chemical and physical structure of pre-stellar and protostellar cores, as well as recent work on protoplanetary disks in their earliest phases of evolution. Links to our Solar System will be made.
- 連絡先
- -名前：久保 雅仁
以上