Apr. 24 Mon 15:00-16:30 Solar and Space Plasma Seminar Zoom / Insei Seminar Room (hybrid)
Apr. 25 Tue 10:00-11:30 太陽系小天体セミナー Zoom
Apr. 26 Wed 10:30-12:00 SOKENDAI Colloquium Zoom / the large seminar room (hybrid)
Apr. 26 Wed 14:00-15:00 Tea Talk Zoom / 輪講室 (hybrid)
Apr. 26 Wed 14:30-15:30 ALMA-J seminar Zoom / ALMA building #102 (hybrid)
Apr. 26 Wed 15:30-17:00 NAOJ Science Colloquium Zoom / the large seminar room (hybrid)
詳細は下記からご覧ください。
=============== Apr. 24 Mon ===============
Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：Apr 24th (Mon), 15:00-16:30
Place： hybrid; Subaru Building / Insei Seminar Room or Zoom
Speaker：Akiko Tei
Affiliation：NAOJ
Title：Observations and Non-LTE Modeling of Off-limb Spicules in the
IRIS Mg II hk lines
Abstract：In order to constrain physical condition of spicules, the elongated and dynamic structures connecting the photosphere to the corona in quiet
regions, we investigated the IRIS Mg II hk lines observed in spicules,
and conducted non-LTE radiative transfer modeling of these lines.
Conducting statistical analysis of a large dataset of both temporally
and spatially well resolved IRIS Mg II lines observed in spicules, we
derived frequency distributions of characteristic quantities of the
lines as a function of altitude, which should reflect the evolution and
physical states of spicules and would constrain spicule models. In the
modeling, we for the first time considered the superposition of
individual spicules along an LOS and demonstrated that the Mg II line
profiles are strongly affected by the presence of multiple spicules
along an LOS. We found that a Mg II profile observed at middle altitudes
is well reproduced by the multi-slab model with a random distribution of
an LOS velocities ranging from -25 to 25 km/s, which are the same extent
as apparent spicule motions. We also showed that the profiles obtained
at higher altitudes in spicules can be reproduced by single-slab models
representing individual spicules, which is consistent with the plausible
situation; less superposition along the LOS occurs at higher altitudes.
In addition, at such higher altitudes, the measured Doppler shifts show
a wide frequency distributions with the Doppler speeds up to 20 km/s,
which is again consistent with the apparent motions of spicules.
Facilitator
-Name：Takayoshi oba
-Comment：in English
=============== Apr. 25 Tue ===============
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25日（火曜日）10時00分～11時30分
場所：zoom
講演者：大坪貴文
世話人の連絡先
名前：渡部潤一
=============== Apr. 26 Wed ===============
Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：April 26, 2023 10:30-12:00
Place：Large Seminar Room in Subaru Building and Zoom
Speaker: Rikuto Omae
Affiliation: SOKENDAI 5th year (D3) (Supervisor: Mami Machida, Masami Ouchi, Kazuhiro Hada)
Title: Review of magnetic fields in the circumgalactic medium using Faraday rotation
Speaker : Raiga Kashiwagi
Affiliation: SOKENDAI 5th year (D3) (Supervisor: Kazunari Iwasaki, Tomoya Takiwaki, Nanase Harada)
Title: Simulation of collisions between filamentary molecular clouds threaded by lateral magnetic field and their evolution
Facilitator
-Name：Matsuda, Graduate Student Affairs Unit
=============== Apr. 26 Wed ===============
キャンパス：三鷹 野辺山 水沢 岡山 ハワイ
セミナー名：Tea Talk
定例・臨時の別：臨時
日時：4/26（水）14：00～15：00
場所：Zoom、輪講室のハイブリッド開催
講演者：大石 雅寿
所属：天文情報センター
タイトル：ジュネーブでの会議と街の様子のご紹介
世話人の連絡先：
-名前：藤田登起子
参加方法：輪講室での対面もしくは、Zoom
=============== Apr. 26 Wed ===============
Campus：Mitaka
Seminar：ALMA-J seminar
Regularly Scheduled/Sporadic： Every Wednesday
Date and time： April 26th, 2023 (Wed), 14:30 – 15:30
Place： ALMA building #102 / Zoom (hybrid)
Speaker: James Miley
Affiliation: Joint ALMA Observatory (JAO) and NAOJ
Title: Searching for disc sub-structure in compact discs: high resolution ALMA observations of the wide binary Sz65 & Sz66
Abstract: Observations using ALMA’s long baselines have been instrumental in revealing substructures related to the mechanisms for planet formation and disc evolution. The resulting data have revealed a plethora of different density sub-structures in young circumstellar discs related to the formation mechanisms of exoplanets. As well as these spectacular poster-children, there also exists a significant population of discs that appear radially compact for which no substructure is resolved at all. Are the large proportion of “compact” discs found in surveys of star forming regions scaled-down versions of the srturctured bright discs? Meaning we require improved sensitivity and resolution to see their fine features? Or are they simply discs without sub-structures, in which the dominant physical mechanisms lead to an alternative evolution of disc density? In this talk I will present an analysis of ALMA’s view of two compact discs in Lupus using new very high angular resolution observations (0.035”, ~5 au). Sz 65 and Sz 66 are a wide binary system (~1000 au separation) in which we search for density sub-structure and investigate the true nature of the previously unresolved compact discs.
Facilitator: Toshiki Saito, Andrea Silva
=============== Apr. 26 Wed ===============
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2023 April 26, 15:30-17:00
Place：zoom / the large seminar room (hybrid)
Speaker：Kazumasa Ohno
Affiliation：NAOJ
Title：TBD
Abstract：TBD
Facilitator
-Name：Akimasa Kataoka
-Comment：English