July 4 Tue 10:00-11:30 太陽系小天体セミナー Zoom
July 5 Wed 10:00-12:00 SOKENDAI Colloquium
Zoom / the large seminar room (hybrid)
July 5 Wed 14:30-15:30 ALMA-J seminar
Zoom / ALMA building #102 (hybrid)
July 5 Wed 15:30-16:30 NAOJ Science Colloquium
Zoom / the large seminar room (hybrid)
詳細は下記からご覧ください。
=============== July 4 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：7月4日（火曜日）10時00分～11時30分
場所：zoom
講演者：匠あさみ
世話人の連絡先
名前：渡部潤一
=============== July 5 Wed===============
Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：July 5, 2023 10:00-12:00
Place：Large Seminar Room in Subaru Building and Zoom
Speaker: Kazuki Watanabe
Affiliation: SOKENDAI 1st year (M1) (Supervisor: Yoshinori Uzawa, Takafumi Kojima, Tai Oshima)
Title: Development of a sub-THz MKID Camera for Deep Space Observation
Speaker : Shubham Bhardwaj
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Maria Dainotti, Nozomu Tominaga, Kazunari Iwasaki)
Title: GRB Optical and X-ray Plateau Properties Classifier Using Unsupervised Machine Learning
Speaker: Ryota Hatami
Affiliation: SOKENDAI 1st year (M1) (Supervisor: Nozomu Tominaga, Tomoya Takiwaki, Koh Takahashi)
Title: Synthesis of Sc, Ti, and V in supernova
Facilitator
-Name：Matsuda, Graduate Student Affairs Unit
=============== July 5 Wed===============
Campus: Mitaka
Seminar: ALMA-J seminar
Regularly Scheduled/Sporadic: Every Wednesday
Date and time: July 5, 2023 (Wed), 14:30-15:30
Place: ALMA building #102 / Zoom (hybrid)
Speaker: Satoshi Ohashi
Affiliation: NAOJ
Title: Dust enrichment and grain growth in a smooth disk around the DG Tau protostar revealed by ALMA triple bands frequency observations
Abstract: Characterizing the physical properties of dust grains in a protoplanetary disk is critical
to comprehending the planet formation process. Our study presents ALMA high-resolution observations
of the young protoplanetary disk around DG Tau at a 1.3 mm dust continuum. The observations,
with a spatial resolution of 0.04 arcsec, or 5 au, revealed a geometrically thin and smooth disk
without substantial substructures, suggesting that the disk retains the initial conditions of the planet formation.
To further analyze the distributions of dust surface density, temperature, and grain size,
we conducted a multi-band analysis with several dust models, incorporating ALMA archival data
of the 0.87 mm and 3.1 mm dust polarization. The results showed that the Toomre Q parameter is
<2 at a disk radius of 20 au, assuming a dust-to-gas mass ratio of 0.01, which means that a higher
dust-to-gas mass ratio is necessary to stabilize the disk. In addition, grain sizes depend on the dust models,
and were found to be less than 0.1 -1 mm in the inner region (r<20 au), while they exceeded larger than 1 mm
in the outer part. Radiative transfer calculations show that the dust scale height is lower than at least
one-third of the gas scale height. These distributions of dust enrichment, grain sizes, and weak turbulence
strength may have significant implications for the formation of planetesimals through mechanisms such as streaming instability.
We also discuss the CO snowline effect and collisional fragmentation in dust coagulation for the origin of the dust size distribution.
Facilitator: Bunyo Hatsukade, Kouichiro Nakanishi
=============== July 5 Wed===============
Campus：Mitaka
Seminar：NAOJ Science Colloquium
Regularly Scheduled/Sporadic：Every Wednesday
Date and time：2023 July 5, 15:30-16:30
Place：Zoom / the large seminar room (hybrid)
Speaker：Satoshi Okuzumi
Affiliation：Tokyo Institute of Technology
Title：Modeling the thermal evolution of planet-forming disks
Abstract：
The thermal structure of protoplanetary disks determines when and
where planets of different compositions form. However, the thermal
structure of these disks remains largely uncertain due to two main
factors: (1) the existence of strong internal heating sources deep
inside the disks is still unknown, and (2) the cooling rate of the disks
is influenced by micron-sized dust grains and varies as the grains grow
into larger solid bodies. Dust growth can even impact disk heating
induced by magnetic fields, as the grains regulate the disks’ electric
conductivity by capturing plasmas. All these factors indicate that the
temperature structure of the disks evolves as planet formation (dust
evolution) progresses. In this presentation, I will discuss our recent
efforts to model the coupled evolution of dust and the thermal structure
of protoplanetary disks. Specifically, I will highlight the roles played
by magnetic fields, disk shadows, and planet-induced spiral shocks in
shaping the disks’ temperature distribution.
Facilitator:
Name：Kazumasa Ohno
Comment：English