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2020.10.5-2020.10.11

10月6日(火)13:30~15:00 太陽系小天体セミナー   zoom
Oct 6 Tue          Solar System Minor Body Seminar                                         

10月7日(水)13:30~15:00  NAOJ Science Colloquium          zoom
Oct 7 Wed 

10月9日(金)16:00~17:00  談話会                  zoom
Oct 9 Fri         NAOJ Seminar         

詳細は以下をご覧下さい。

10月6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6日(火曜日)13時30分~15時
場所
zoom
講演者
長谷川均
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7日(水)

Campus
Mitaka
Seminar
NAOJ Science Colloquium
Regularly Scheduled/Sporadic
Every Wednesday
Date&Time
2020 October 7, 13:30-15:00
Place
Zoom
Speaker
Misako Tatsuuma (Univ. of Tokyo, *Student talk)
Title
Formation Process of Small Solar System Bodies Investigated by Material Strength of Dust Aggregates
Abstract
On the formation of small solar system bodies, there are many theories such as direct coagulation growth, pebble accretion, and some instabilities. To investigate the formation process, we focus on the material strength of these bodies. The internal density of bodies larger than several hundred meters is thought to be determined by the balance between self-gravity and compressive strength. In this work, we calculate the compressive strength of micron-sized dust aggregates by using dust N-body calculation. As a result, we succeeded in calculating the compressive strength of ice and silicate dust aggregates continuously from the volume filling factor of less than 0.1 to high density. Then, we calculate the internal density of the dust aggregates by assuming the balance between the self-gravity and compressive strength and compare it with the internal density of small solar system bodies. We found that the trans-Neptunian objects (TNOs) can be explained by ice dust aggregates, while comets including 67P/Churyumov-Gerasimenko can be explained by silicate dust aggregates. On the other hand, the densities of the asteroids Ryugu and Bennu are too dense to be explained by the dust aggregates in this work. To form such dense objects, it is necessary to form tens-kilometer-sized objects. In other words, we suggest that Ryugu and Bennu are collections of debris, and their parent bodies’ size is tens of kilometers or more.

Language
English
Facilitator
-Name:Akimasa Kataoka
-Affiliation:Division of Science
Comment
NAOJ Science Colloquium Home page
URL: https://sci.nao.ac.jp/seminars/colloquium/

10月9日(金)

Campus
Mitaka
Seminar
NAOJ Seminar (国立天文台談話会)
Regularly Scheduled/Sporadic
Scheduled
Date and time
10/9 (Fri) 16:00-17:00
Place
Zoomウェビナー
Speaker
田中 圭
Affiliation
国立天文台 アルマプロジェクト
Title
“食塩と熱水に包まれた双子の大質量原始星”
Abstract
大質量星は様々な天文分野において非常に重要な天体ですが、個数も少なく分厚いガスに覆われて誕生するため、その形成過程には多くの謎が残されています。近年、理論的には大質量星も小質量星と同様に円盤を介した質量降着によって形成することが支持されつつありますが、観測による実証はまだ不十分な状況です。本公演では私たちの最近の成果、特にALMA高解像度観測による大質量原始星円盤中の塩化ナトリウム分子の発見と、その意義について報告させていただきます。
Facilitator
-Name:青木 和光

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