Home > ALMA Jセミナー | 太陽系小天体セミナー | 科学研究部コロキウム > 2020.10.12-2020.10.18

2020.10.12-2020.10.18

10月13日(火)13:30~15:00 太陽系小天体セミナー   zoom
Oct 13 Tue          Solar System Minor Body Seminar  

10月14日(水)13:30~15:00  NAOJ Science Colloquium          zoom
Oct 14 Wed 

10月14日(水)15:00~16:00  ALMA-J seminar               zoom
Oct 14 Wed                  

詳細は以下をご覧下さい。

10月13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13日(火曜日)13時30分~15時
場所
zoom
講演者
高橋昂希
所属
北海道教育大学
タイトル
C/2019 Y4(Atlas)の偏光観測
Abstract
2020年の3月末から5月頭にかけて北海道大学附属天文台の1.6m ピリ
カ望遠鏡でC/2019 Y4(Atlas)の偏光観測を行いました。
C/Atlasは増光が期待されていましたが、4月に入ると崩壊した様子が報告されま
した。
偏光観測の結果、C/Atlasの偏光度はC/1995 O1(Hale-Bopp)やC/1996
B2(Hyakutake),D/1999 S4(LINEAR)より小さく、D/1996 Q1(Tabur)に近いことが
わかりました。
また、偏光度の減少が4/3に確認できたので崩壊との関連性について議論したい
です。
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14日(水)

Campus
Mitaka
Seminar
NAOJ Science Colloquium
Regularly Scheduled/Sporadic
Every Wednesday
Date
2020 October 14
Time
13:30-15:00
Place
Zoom
Speaker
Rei Enokiya (Keio Univ.)
Title
Cloud-cloud collisions and triggered star formation in the Central Molecular Zone
Abstract
We will discuss the massive cluster formation in the Central Molecular Zone by applying a new method to identify a cloud-cloud collision which has been developed in the Galactic HII regions and the young massive clusters in the Local Group and the Antennae galaxies.
The Central Molecular Zone harbors outstanding clusters including the Arches and Quintuplet, and it is an issue of keen interest to understand the mechanism of the cluster formation (e.g., Longmore+ 2013, MNRAS, 433, 15). Recently, some authors reported that cloud-cloud collisions (CCCs) trigger the young massive cluster formation in the LMC (R136; Fukui+ 2017, PASJ, 69, 5) and in the Antennae Galaxies (Tsuge+ 2019, ApJ, 871, 44). The CMZ, which holds the highest volume density of molecular gas in the Local Group, is expected to have very frequent CCCs and it is important to test if CCC provides a viable mechanism of cluster formation in the CMZ at the highest resolution thanks to its small distance. There are already several studies which reported CCCs in localized areas in the CMZ (Sgr B2, Hasegawa+ 1994, ApJ, 429, 77; the 50 km/s cloud, Uehara+ 2019, ApJ, 872, 121). In order to obtain a unified picture on the role of CCC over the whole CMZ, we undertook a new analysis of collision signatures based on the archival CO datasets by applying the identification method of CCC, which is developed in the Galactic disk clouds including the outstanding HII regions M42, M17, and NGC6334 (Fukui+ 2018, ApJ, 859, 166; Nishimura+ 2018, PASJ, 70, 42; Fukui+ 2018, PASJ, 70, 41). We have found evidence for CCCs in the three major, active star-forming regions in the CMZ, namely Sgr A, Sgr B2, and Sgr C, at different evolutionary stages, where Sgr B2 is the youngest and most active site of high-mass star formation. The mass, relative velocity, and collision time scale in the CCC are 105-6 Msun, several ten km/s, and 105-6 yrs, respectively. We discuss that these GMC collisions may play a significant role in the context of the star forming history in the CMZ and moreover in the evolution of the Galaxy. The CCCs in the present analysis can be driven by the bar potential model (e.g., Binney et al. 1991, MNRAS, 252, 210), whereas an alternative mechanism is the magnetic instability which can drive gas motion with the Alfven velocity of ~30-50 km/s; the field strength of the inner several 100 pc is estimated to be at least 50 micro Gauss (Crocker+ 2010, Nature, 463, 65), and the huge molecular loops 1, 2, and 3 discovered within several 100 pc of the GC provide observational evidence for the Parker instability driven by the field with ~100 mG (Fukui+ 2006, Science, 314, 106). Suzuki+ (2015), MNRAS, 454, 3049 and Kakiuchi+ (2018), MNRAS, 476, 5629 demonstrated that the Parker instability generates large velocity dispersions at the foot points of magnetically floated loops, leading to a collision between the magnetic driven gas with the disk.
NAOJ Science Colloquium Home page
URL: https://sci.nao.ac.jp/seminars/colloquium/
Facilitator
-Name:Akimasa Kataoka

10月14日(水)

Campus
Mitaka
Seminar
ALMA-J seminar
Regularly Scheduled/Sporadic
Every Wednesday
Date and time
2020 Oct 14 15:00-16:00
Place
Zoom
Speaker
Satoko Takahashi
Affiliation
NAOJ Chile
Title
ObsMode process: how are new ALMA capabilities prioritized, tested, and offered?
Abstract
ObsMode is a yearly process which aims at preparing observing modes and capabilities for the ALMA new Observing cycles. The final goal of the ObsMode process is to deliver new observing capabilities for the PI science observations following the annual timelines. Since March this year, I have been leading the ObsMode process based at JAO. In this talk, I will explain ObsMode activities in 2020, particularly how the ObsMode process has progressed under the current pandemic situation. I would also like to introduce contributions from the EA ARC colleagues.
Facilitator
Daisuke Iono, Andres Guzman

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