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2022.7.11-2022.7.18

July 12 Tue 10:00~11:30 太陽系小天体セミナー Solar System Minor Body Seminar zoom

July 13 Wed 10:30~12:00  SOKENDAI Colloquium            zoom

July 13 Wed 15:30~17:00  NAOJ Science Colloquium           zoom

July 14 Thu 10:00~11:00  Tea Talk                   zoom

July 15 Fri 16:00~17:00 談話会 NAOJ Seminar         zoom

詳細は以下をご覧下さい

7月12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:7月12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

7月13日(水)

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:July 13th, 2022 10:30-12:00
Place:zoom

Speaker 1: Itsuki Ogami
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Wako Aoki, Hisanori Furusawa, Miho Ishigaki)
Title: The nature and structure of the stellar halo of the Andromeda galaxy using Subaru/HSC NB515

Speaker 2: Yoshiaki Sato
Affiliation: SOKENDAI 1st year (M1) (Supervisor: Noriyuki Narukage, Takashi Sekii, Masumi Shimojo)
Title: Study of High-Energy Phenomena in the Solar Corona Tackled with X-ray Imaging-Spectroscopy

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

7月13日(水)

Campus:Mitaka
Seminar:NAOJ Science Colloquium
Regularly Scheduled/Sporadic:Every Wednesday
Date and time:2022 July 13, 15:30-17:00
Place:zoom / Instrument Development Bldg. 3 (hybrid)
Speaker:Seo Chanoul
Affiliation:NAOJ (D2)
Title:Atmospheres of sub-Neptune-sized exoplanets in contact with magma ocean
Abstract:Sub-Neptunes are small exoplanets (Planetary radius = 2~3 Earth radius) with voluminous atmospheres and are important targets of future recent and upcoming transit spectroscopy. However, the framework to relate their atmospheric properties to their hidden interior and the formation pathway has not been well established. As the mass of sub-Neptunes is dominated by the silicate core, their atmospheres are likely to be affected by the reaction with the underlying magma (i.e., molten rock) if they exist. Thus, we study the atmospheric composition of sub-Neptunes in the presence of magma ocean using an equilibrium model of the Fe-Si-Mg-H-C-O system with Fe-FeO-Fe2O3 magma redox buffer. We find the nebula-origin atmospheres can be highly oxidized to form H2O-dominated atmospheres when the accreted amount of volatile is moderate and(or) the iron core fraction is small. We show how the two observable atmospheric parameters, H2O fraction and atmospheric C/H ratio, in the combination of the measurement of mass and radius, can infer the initial magma redox state and composition of accreted volatiles (nebula gas and pure ice). The high solubility of H2O into magma and the small solubility of C-bearing species enrich C-bearing species in the atmosphere, which could be used as an indicator of the presence of magma-atmospheric reaction. Such properties of atmospheres may also provide a way to distinguish several suggested formation scenarios of small planets around M-type stars.

Speaker:Kinoshita Shinichi
Affiliation:NAOJ (D2)
Title:MHD simulation of cluster formation in clumps
Abstract:It is well known that stars are often born in clusters. Thus, understanding cluster formation is very important to grasp the general picture of star formation and the evolution of the galaxy. In recent studies, the cluster-forming clumps are considered to be the parent objects of clusters (Lada & Lada 2003). Cluster-forming clumps tend to exhibit complex velocity structures with several velocity components. One of the hypotheses to explain these velocity fields is the collisions of clumps (e.g., Higuchi et al. 2010). Clump-Clump Collision is proposed as a possible mechanism for triggering the formation of clusters. On the other hand, some studies show that complex velocity structures can be explained by the infalling motion of a single clump with rotation (e.g., Shimoikura et al. 2016). Some expect that such a dynamical infall is a common phenomenon for cluster-forming clumps. In this way, several hypotheses have been proposed, and the formation and evolution processes of clusters still remain unclear.
In this talk, I will show some results of the MHD simulation of cluster formation. We investigated the cluster formation in a single clump infalling with rotation. We will discuss the dynamical evolution of clumps and the properties of dense cores.

Facilitator
-Name:Akimasa Kataoka
Comment:English

7月14日(木)

キャンパス:三鷹
セミナー名:Tea Talk
定例・臨時の別:臨時
日時:7/14(木)10:00~11:00
場所:Zoom
講演者:佐藤幹哉、渡部潤一
所属:天文情報センター
タイトル:ヘルクレス座τ流星群アメリカ観測遠征記

世話人の連絡先:
-名前:藤田登起子

7月15日(金)

Campus:Mitaka
Seminar:談話会 NAOJ Seminar
Regularly Scheduled/Sporadic:Every Friday
Date and time:2022 July 15, 16:00-17:00
Place:zoom
Speaker: 札本 佳伸 / Fudamoto, Yoshinobu
Affiliation:国立天文台 アルマプロジェクト・早稲田大学 / ALMA Project, NAOJ ・ Waseda University
Title:ALMA大規模探査REBELS: 宇宙初期の隠された銀河進化
Abstract:宇宙初期(宇宙年齢10億年以下)に存在する銀河を発見・観測することは銀河の進化過程を理解する上でとても重要である。これまで、高赤方偏移銀河の探査においてはすばる望遠鏡などの可視・近赤外望遠鏡を用いた探査・観測によって、宇宙初期に存在する銀河が多数発見されてきた。しかしながら、これらの可視・近赤外望遠鏡による探査では見逃されている銀河も多く存在するのではないかということも長く指摘されていた。特に、銀河内部の星形成活動により作られるダストが内部に多く存在するような銀河は、星の光が銀河の外に出る前にダストに吸収されてしまうため可視・近赤外線で非常に暗くなり発見が困難となる。近年、アルマ望遠鏡の観測により宇宙初期におけるダストに隠された銀河の活動に対する研究が急速に進んできた。今回、2019年から続けられているアルマ望遠鏡の大規模探査「REBELS」により判明した宇宙初期に存在する銀河のダストに隠された活動、そして新たに発見された銀河についての報告を行う。

Facilitator
-Name:藤井 友香 / Fujii, Yuka


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