Oct 4 Tue 10:00～11:30 太陽系小天体セミナー Zoom
Oct 5 Wed 14:30～15:30 ALMA-J Seminar Zoom
Oct 5 Wed 15:30～17:00 NAOJ Science Colloquium Zoom/Instrument Development Bldg.3
Oct 6 Thu 17:00～18:00 Astrochemistry seminar Zoom
Oct 7 Fri 16:00～17:00 NAOJ Seminar Zoom/Large Seminar Room
詳細は以下をご覧下さい
10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：10月4日（火曜日）10時00分～11時30分
場所：zoom
講演者：鈴木文二
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
10月5日（水）
Campus：Mitaka,
Seminar：ALMA-J seminar
Regularly Scheduled/Sporadic： Every Wednesday
Date and time：5th October (Wed), 14:30 – 15:30
Place：Zoom
Speaker：Toshiki Saito (NAOJ)
Affiliation：NAOJ
Title：Inspecting Negative AGN feedback in the prototypical Seyfert 2 galaxy NGC 1068
Abstract：
Active galactic nucleus (AGN) feedback is postulated as a key mechanism for regulating star formation within galaxies. Studying the properties of the outflowing gas from AGNs is thus crucial for understanding the coevolution of galaxies and supermassive black holes. In this talk, I present our “cloud-scale” ALMA Band 3/6 spectral scan and Band 8 [CI] observations toward the central 1-kpc of the nearby Seyfert 2 galaxy NGC 1068. Our analysis revealed the kinematical, chemical, and physical characteristics of the negative AGN feedback happening in one of the nearest Seyfert galaxies.
Facilitator
-Name：Masumi Shimojo, Yu Cheng
10月5日（水）
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2022 Oct. 5, 15:30-17:00
Place：zoom / Instrument Development Bldg. 3 (hybrid)
Speaker：Zsolt Keszthelyi
Affiliation：NAOJ
Title：The effects of surface fossil magnetic fields on massive star evolution
Abstract：Magnetism plays a vital role in several astrophysical phenomena, from the scale of sub-atomic particles up to galaxy clusters. Studying stellar magnetic fields can help us better understand planetary habitability, stellar variability, and the overall magnetic flux evolution from star formation to compact objects.
There has been renewed interest in this field, partly due to the surprising discovery that some massive stars host strong, globally organized, large-scale magnetic fields. The long-term (years to decades-long) spectropolarimetric monitoring shows a lack of correlation with stellar parameters. This suggests that the observed fields of early-type stars are not produced by a dynamo mechanism. Instead, they are thought to be remnants from the earlier history of the star (from the star formation phase or, in part, produced by stellar mergers).
In a series of publications, we have been studying the long-term, evolutionary impact of such fossil fields on massive star evolution. Two main effects concern i) trapping wind material and thus reducing the mass loss and ii) magnetic braking leading to slowly spinning stars. Both have far-reaching consequences and could affect completely evolutionary pathways, stellar populations, predictions on stellar end products, and gravitational wave progenitors.
We recently computed and scrutinized a grid of models including these effects in three metallicity environments. The library of new stellar models is open source and available for the community via: https://zenodo.org/record/7069766
Facilitator
-Name：Akimasa Kataoka
-Comment：English
10月6日（木）
Campus：Mitaka
Seminar：Astrochemistry seminar
Regularly Scheduled/Sporadic：Sporadic
Date and time：2022 Oct 6, 17:00-18:00
Place：zoom
Speaker：Tom Millar
Affiliation：Queen’s University Belfast
Title：Internal UV photons and the chemistry of AGB stars
Abstract：
It has been known for some years that the chemistry in the outer
circumstellar envelopes of AGB stars is dominated by interstellar
photon-driven processes and that some stars contain companions that
perturb the density profile of their outflows. The recent ALMA Large
Programme ATOMIUM, a Band 6 213-270 GHz line survey of 15 O-rich and 2
S-type evolved stars, shows that all contain non-symmetric density
distributions with the presence of arcs, spirals, outflows and
equatorial density enhancements that indicate the presence of a
(sub)stellar companion. In some systems the companion is detected but
in most their nature is hidden from us. ALMA observations of specific
molecules also indicate the presence of ‘unexpected’ species at a few
stellar radii. These include the presence of hot water and methyl
cyanide in IRC+10216 at abundances not in agreement with either LTE or
chemistry in gas shocked by stellar pulsations. I will discuss some
attempts to explain such results, one in which the O-rich and C-rich
outflows are clumpy and porous and another that assumes a companion
provides a source of internal UV radiation which can perturb the
chemistry. More recently, we have explained ALMA observations of a
surprisingly high abundance of HC3N in the inner region of IRC+10216 by
a chemistry modulated by a companion UV field. Finally, I will
introduce an upcoming version of the UMIST Database for Astrochemistry
(UDfA) that reflects the additional chemistry needed to model the 100 or
so new molecules detected in the last decade. I hope to release this new
version to the public in early 2023.
Facilitator
-Name：Nanase Harada
-Comment：English
10月7日（金）
Campus: Mitaka
Seminar: NAOJ seminar
Regularly Scheduled/Sporadic: Every Friday
Date and Time: 2022 October 7 16:00-17:00
Place: Zoom / Large Seminar Room
Speaker:吉田 滋 / Shigeru Yoshida(千葉大学ハドロン宇宙国際研究センター / International
Center for Hadron Astrophysics, Chiba University)
Title: 高エネルギーニュートリノと電磁波観測のタッグで解き明かす躍動する宇宙の起源
Abstract:
宇宙を舞台とする極限現象は、例えば中性子内部やブラックホール近傍に代表される超高密度環境、
あるいは、可視光に比して20桁以上高いエネルギーをもつ宇宙線放射を引き起こすほどの超高エネ
ルギープラズマ環境において繰り広げられる。しかし、こうした舞台は電磁波を遮蔽する宇宙の
「大奥」であることが多く、何がそこで起こっているかを理解する糸口を掴めないままであった。
しかし、南極点直下の深氷河内に莫大な容積のニュートリノ検出網を建設したIceCube 実験によっ
て、弱相互作用素粒子であるニュートリノが TeV (1兆電子ボルト)から PeV (千兆電子ボルト)もの
超高エネルギー領域において放射されていることが発見され、ニュートリノを使って超高密度・超
高エネルギー現象を引き起こす天体を同定することが可能な時代に突入した。こうした天体候補は、
ブレーザーのフレア、コア崩壊型超新星、ジェット駆動形超新星、低輝度ガンマ線バースト、TDE
などの突発天体である。
これらの天体の物理現象の研究は、強大な重力場が作り出すプラズマの成長過程から、超高エネル
ギー宇宙線放射にまで至る、重力エネルギーの最終運命を統一的に理解することと同義である。本
講演では、これまでのニュートリノ観測の成果を概観したのち、透過力に優れ、(素)粒子衝突の物
理情報を持ち出せるニュートリノ観測と、角度・空間・波長分解能に優れた電磁波観測でタッグを
組むことで、未開の極限宇宙像を観測的に描き出す提案について解説する。
Facilitator: 守屋 尭 / Moriya, Takashi