Home > 太陽系小天体セミナー | 科学研究部コロキウム > 2022.1.17-2022.1.23


JAN 18 Tue 10:00~11:30  太陽系小天体セミナー / Solar System Minor Body Seminar  zoom

JAN 19 Wed 15:30~17:00  NAOJ Science Colloquium    zoom






Seminar:NAOJ Science Colloquium
Regularly Scheduled/Sporadic:Every Wednesday
Date and time:2022 Jan 19, 15:30-17:00
Speaker:Shinichi Kinoshita
Affiliation:NAOJ Students Talk (D1)
Title:Dense core collision using MHD simulation
Abstract:The collision between clouds in the ISM is an important phenomenon to study, and there is increasing observational evidence that cloud–cloud collisions trigger stars and cluster formation in the Milky Way. Observational evidence of triggered star formation by cloud-to-cloud collisions comes mainly from relatively large scale star formation events that produce massive stars and clusters. Therefore, many numerical studies to date have been concerned with collisions between high mass clouds. However, in turbulent molecular clouds, a core collision may occur on a smaller scale. In turbulent molecular clouds, due to the randomness of gas velocities, small over-densities can be formed throughout the cloud and dense core collisions can occur due to the velocity dispersion between them.
We investigate, using three-dimensional magnetohydrodynamical (MHD) simulations, core collisions between two stable dense cores. In our simulations, we considered the effect of magnetic fields on the collision process and focused on their observational features. In this presentation, I will discuss the evolution of dense core collisions and comparison with observational data.
Speaker:Tomohiro Yoshida
Affiliation:NAOJ Students Talk (M1)
Title:A new measurement method of isotopologue ratios in protoplanetary disks: a case study of the 12CO/13CO ratio in the TW Hya disk
Abstract:Planetary systems are thought to be born in protoplanetary disks. Isotope ratios are a powerful tool for investigating the material origin and evolution from molecular clouds to planetary systems via protoplanetary disks. However, it is challenging to measure the isotope (isotopologue) ratios, especially in protoplanetary disks, because the emission lines of major species are saturated. We developed a new method to overcome these challenges by using optically thin line wings induced by thermal broadening. As a first application of the method, we measured the 12CO/13CO ratio in the TW Hya protoplanetary disk. 12CO/13CO was estimated to be ~23, which is significantly smaller than the typical ISM value (~69) in the inner disk. In contrast, it is suggested that 12CO/13CO is higher than >100 in the outer disk. Our results imply that the gas-phase 12CO/13CO can vary by a factor of >5 even inside a protoplanetary disk, and therefore, can be used to trace material evolution in disks.

-Name:Akimasa Kataoka

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