カテゴリー: 総研大コロキウム

October　31　Tue　 　10:00-11:30　　太陽系小天体セミナー　　　　Zoom
　　　　　　　　　　　　　　　　　　　　

October　31　Tue　　15:30-16:30 　　 NAOJ Seminar　
　　　　　　　　　　　　　　　　　　　Zoom/Large Seminar Room (hybrid)　　　　　　　　　　　　　

November　1　Wed　10:30-12:00 　　SOKENDAI Colloquium　
　　　　　　　　　　　　Large Seminar Room in Subaru Building and Zoom

November　1　Wed　14:30-15:30　　 ALMA-J seminar 　
　　　　　　　　　　　　hybrid (ROOM102 in ALMA building and ZOOM)

November　1　Wed　15:30-16:30　　 NAOJ Science Colloquium 　
　　　　　　　　　　　　　　the rinkoh seminar room / Zoom (hybrid)

November　2　Thu　11:00-12:00 　　Tea Talk　　　　　　　Zoom

詳細は下記からご覧ください。

=============== October 　31　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：10月31日（火曜日）10時00分～11時30分
場所：zoom
講演者：藤井大地

世話人の連絡先
　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

=============== October 　31　Tue==============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：October 31, 2023 15:30-16:30
Place：Zoom/Large Seminar Room (hybrid)

Speaker：Ruobing Dong, PhD
Affiliation：University of Victoria

Title：Observational Planet Formation
Abstract:
It is hard to see a plane cruising at 10 km during daytime, as the plane is
tiny and faint on the sky. But, if we can see the contrail tailed behind the
plane, we know where the plane is. Now, astronomers are applying the same
principle to study how planets form, by detecting and charactering the
structures baby planets produce in their birth cradles – protoplanetary
disks. This is a new field largely driven by discoveries made by some of the
largest and most advanced telescopes ever built. I will introduce the
current status of the field, and highlight some of the latest developments
as well as unsolved problems.

Facilitator
-Name：Prof. Nomura, Hideko

=============== November　1　Wed==============

Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：November 1, 2023 10:30-12:00
Place：Large Seminar Room in Subaru Building and Zoom

Speaker: Ryota Hatami
Affiliation: SOKENDAI 1st year (M1) (Supervisor: Nozomu Tominaga, Tomoya Takiwaki, Koh Takahashi)
Title: Synthesis of Sc, Ti, and V in core-collapse Supernovae toward constraining explosion mechanism

Speaker: Masato Sato
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Nozomu Tominaga, Tomoya Takiwaki, Takashi Moriya)
Title: Exploring electron-capture supernovae in past observations

Facilitator
-Name：Matsuda, Graduate Student Affairs Unit

=============== November　1　Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Nov 1st (Wed) 14:30-15:30
Place: hybrid (ROOM102 in ALMA building and ZOOM)
Speaker: Ceci Xue
Affiliation: MIT
Title: Molecular Spectra Diagnostics with a Bayesian MCMC Approach
Abstract:
The recent improvement in receiver technology within modern facilities has enabled us to efficiently perform wide-band and high-sensitive molecular line surveys. To better extract the information from these wide-band spectral data, we introduce a molecular signal diagnostic tool coupling a non-LTE radiative transfer model and a Markov Chain Monte Carlo (MCMC) approach. Based on RADEX (van der Tak et al. 2007), our tool features novel implementations to support multiple components along the line of sight and allow Bayesian inference about physical characteristics. In contrast to a canonical least-squares fit approach, MCMC analyses allow a more efficient exploration of the physical parameter space and provide access to the parameter’s probability distribution, which can be used to characterize the confidence intervals and covariances between parameters. In this talk, following a brief introduction to Bayesian statistics, we will present a case study demonstrating the analysis of molecular line observations from ALMA using this tool. Specifically, we will share the first detection and mapping of the Class I methanol maser at 84 GHz toward the north region of Sagittarius B2 molecular cloud. We resolved the regions where the maser emission originates and assessed their observed spectral profiles respectively. The results suggest a chained two-component model for explaining the intense methanol Class I maser emission toward a region with weak continuum background radiation. In addition, our diagnostic tool will be applied to the spectral line survey, GOTHAM, which has a total bandwidth of 25GHz, to conduct the full chemical census toward the TMC-1 dark cloud.

Organizers: Gianni Cataldi, Hiroshi Nagai

=============== November　1　Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Nov. 1 (Wed.), 15:30-16:30
Place: the rinkoh seminar room / Zoom (hybrid)

Speaker: Biagio De Simone
Affiliation: UNISA
Title: An Optical Gamma-Ray Burst catalogue with Measured Redshift: Data Release of 533 Gamma-Ray Bursts and colour evolution
Abstract:
Gamma-Ray Bursts (GRBs) are incredibly energetic cosmic phenomena observed across a wide range of wavelengths, including gamma-ray and optical frequencies, and occasionally even in radio waves. They allow extending the Hubble diagram and the cosmological analysis up to redshift z=9.4, much further than Supernovae Ia (z=2.26).
We therefore present a compilation of 533 optical lightcurves (LCs) of all GRBs with measured redshifts, detected mainly by Swift and 418 ground-based telescopes from February 28, 1997, to April 14, 2023. This catalogue is the largest optical repository of GRB LCs with redshifts to date, with 64615 photometric data points, including upper limits. Our user-friendly web tool, grbLC, allows the acquisition of GRB LCs, including information on the position, redshift, and a Gamma-ray Coordinates Network (GCN) crawler that can be used to collect data by gathering magnitudes from the GCNs. The web tool also includes a package for uniformly investigating colour evolution. We have crafted a procedure to distinguish between GRBs in our sample, which undergo colour evolution, and GRBs for which no colour evolution is present. We compared our results with the literature. This web-based archive is the first step towards unifying several community efforts to gather optical LCs by providing a unified format and repository for the optical catalogue. This catalogue will enable population studies by providing LCs with better coverage since we have gathered data from different ground-based locations, resulting in fewer gaps in the LCs and representing crucial support for the LC reconstructions analysis.

Speaker: Chanoul Seo
Affiliation: NAOJ
Title: Impact of Magma Redox States on Super-Earth Atmospheres:
Unveiling the Connection with Atmospheric Composition
Abstract:
Most exoplanets with radii larger than ~1.6Earth mass are more inflated than bare-rock planets with the same mass, indicating a substantial amount of volatile. While it is hard to constrain the origin of the volatiles or the planet’s bulk composition only from the mass-radius relation, the spectral characterization of their atmospheres is expected to solve this degeneracy. Previous models pointed out that the interaction between the accreted volatile and the likely molten rock (i.e., magma) beneath the atmosphere would affect the atmospheric composition significantly. However, existing models do not clarify the dependence of the atmospheric compositions with major spectral fingerprints on the observable planetary parameters. In this work, we explore the possible range of H, O, and C in the atmosphere of exoplanets as a function of observable planetary parameters (mass, radius, equilibrium temperature) using a simple chemical equilibrium model. Consistent with the previous work, we show that the water fraction in contact with magma ocean is the order of 10^-2~10^-1 if the dry planetary core accretes the nebula gas. Due to the difference in solubility of H-bearing and C-bearing species in molten rock, C/H shows an increase of ×3~10^2. The low values correspond to H2-rich atmospheres while the high values (the order of magnitude difference) correspond to the thin atmosphere with pressure <10^3 bar. Therefore, the C/O remains relatively low in most of the parameter range considered, below one-tenth of the nebula gas value if the atmospheric H2O fraction is over five percent. These trends provide a clue to verify or falsify the formation scenario of super-Earth/sub-Neptune from atmospheric compositions.

Facilitator
-Name: Maria Giovanna Dainotti
Comment: English

=============== November　2　Thu==============

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：11/2（木）11：00～12：00
場所：Zoom（のみ）
Speaker:Hannah Harris
Title:
International Scientific Cooperation with North Korea: from Ancient Astronomy to Today

Abstract:
The Korean Peninsula is home to an ancient and unique tradition in astronomy. Beginning with the prehistoric Stone Age and blossoming over the last two thousand years, astronomy is deeply enmeshed in Korean culture. It is unsurprising that North Korea, just like its neighbor to the South, continued this scientfic tradition. Yet astronomy and science in North Korea is still relatively unknown and understudied. Today, North Korean scientists are active participants in the international scientific community across many fields and disciplines. This talk presents the history and future prospects for international scientific cooperation with North Korea with an emphasis on astronomy.

Short bio:
Hannah Harris is a Canadian-American science communicator, researcher, and a current Marie Sklodowska-Curie Fellow with the International Atomic Energy Agency (IAEA). She has a Bachelor’s degree in Astrophysics from Wellesley College (USA) and researched spinning black holes at the MIT Center for Theoretical Physics and the Gravitational Physics Group at Cardiff University (Wales, UK). Recently, she finished a dual-degree masters program between Russia and the United States, where she studied nuclear physics, nuclear energy, and nuclear weapons, as well as international relations. Her thesis focused on scientific research in North Korea and the possibilities for nuclear risk reduction through peaceful scientific cooperation. Since 2014, she has collaborated with the IAU on a variety of space policy and outreach projects and served as the project manager for the “Inclusive Astronomy” programme during the IAU100 centennial celebrations in 2019.

世話人の連絡先：
-名前：藤田登起子
参加方法：Zoom

Oct 17 Tue 　10:00-11:30 　 太陽系小天体セミナー Zoom

Oct 17 Tue 　13:30-14:30 NAOJ Seminar zoom/ Large seminar room in Subaru Building

Oct 18 Wed 　10:30-12:00 　 SOKENDAI Colloquium Hybrid;Large Seminar Room in Subaru Building and Zoom

Oct 18 Wed 　14:30-15:30 ALMA-J seminar hybrid (ROOM102 in ALMA building and ZOOM)

Oct 18 Wed　 15:30-16:30 NAOJ Science Colloquium The large seminar room / Zoom (hybrid)

詳細は以下をご覧下さい。

=============== October　17　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：10月17日（火曜日）10時00分～11時30分
場所：zoom
講演者：藤原康徳

世話人の連絡先
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

=============== October　17　Tue===============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regularly Scheduled Date and time：2023 Oct 17, 13:30-14:30
Place：zoom/ Large seminar room in Subaru Building

Speaker：Dr,Bruno Dias
Affiliation: President, Sociedad Chilena de Astronomía (SOCHIAS) Professor, Institute of Astrophysics, Department of Physics, Faculty of Exact Sciences, Universidad Andrés Bello (UNAB), Chile

Title:　The Chilean Astronomical Society (SOCHIAS)

Abstract: The Chilean Astronomical Society (SOCHIAS) was founded on May 31, 2000 with the goals of boosting Astronomy in Chile, managing the interests of Chilean astronomers, organising scientific meetings, establishing and maintaining contact with organizations in Chile and abroad, and supporting Astronomy education, among other related objectives. In this context, two representatives of the current SOCHIAS board are visiting Japan, and in this presentation we will show some information about SOCHIAS as well as some of our initiatives. We hope to keep and strengthen the relationship among Japanese and Chilean astronomical communities.

Facilitator
-Name：Izumi Takuma

=============== October　18　Wed===============

Campus： Mitaka
Seminar： SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Regular
Date and time：October 18, 2023 10:30-12:00
Place： hybrid; Large Seminar Room in Subaru Building and Zoom

Speaker: Moka Nishigaki
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Masami Ouchi, Tadafumi Takata, Kimihiko Nakajima)
Title: Modeling the Mass-Metallicity Relation with Dark Matter Halo Assembly from z=0–10

Speaker: Kuria Watanabe
Affiliation: SOKENDAI 2nd year (M2) (Supervisor: Masami Ouchi, Nozomu Tominaga, Masato Onodera)
Title: The Chemical enrichment and origin of Nitrogen-Rich Galaxies at High Redshift

Facilitator
-Name：Matsuda, Graduate Student Affairs Unit

=============== October　18　Wed===============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Oct 18th (Wed) 14:30-15:30
Place: hybrid (ROOM102 in ALMA building and ZOOM)

Speaker: Pei-Ying Hsieh
Affiliation: NAOJ

Title:The circumnuclear disk revealed by ALMA – environments of star formation in the inner 10 pc of the Galaxy

Abstract:The molecular 2-pc circumnuclear disk (CND) immediately around the Milky Way supermassive black hole (SMBH), SgrA, resembles the “molecular torus” in AGNs, providing a unique opportunity to study SMBH accretion and nuclear star formation at sub-parsec scales. In recent years, I have been studying the key question of how much of the available gas can actually form stars in the environment around Sgr A, and how material is being moved around and accreted in this region. The lifetime of the CND has been a long-standing debate over the past decade. The CND can not live longer than 10^5 years if the gas density is under the tidal threshold of SgrA/nuclear star clusters, thus depleting the source of fuel and star formation. Utilizing the ALMA and various single-dish telescopes, we present CS line maps toward the CND of the Galactic Center. Our primary goal is to resolve the compact structures within the CND and the streamers, in order to understand the stability conditions of molecular cores in the vicinity of Sgr A. Our data provide the first homogeneous high-resolution (1.3″ = 0.05 pc) observations aiming at resolving density and temperature structures. A stability analysis based on the unmagnetized virial theorem including tidal force shows that 84 (+16/-37) % of the total gas mass (2.5X10^4 Msun) is tidally stable, which accounts for the majority of gas mass. Turbulence dominates the internal energy and thereby sets the threshold densities 10-100 times higher than the tidal limit at distance >1.5 pc to Sgr A*, and therefore, inhibits the clouds from collapsing to form stars near the SMBH.

Organizers: Gianni Cataldi , Hiroshi Nagai

=============== October　18　Wed===============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Oct. 18 (Wed.), 15:30-16:30
Place: The large seminar room / Zoom (hybrid)

Speaker: Yoshiaki Misugi
Affiliation: NAOJ

Title: Evolution of the Angular Momentum of Molecular Cloud Cores in Filamentary Molecular Clouds

Abstract:
The angular momentum of molecular cloud cores plays a key role in the star formation process. However, the evolution of the angular momentum of molecular cloud cores formed in magnetized molecular filaments is still unclear. We perform three-dimensional magnetohydrodynamics simulations to reveal the evolution of the angular momentum of molecular cloud cores formed through filament fragmentation. As a result, we find that the angular momentum decreases by 30% and 50% at the mass scale of
1 Msun in the case of weak and strong magnetic field, respectively. By analyzing the torques exerted on fluid elements at different mass scales, we identify the magnetic tension as the dominant process for angular momentum transfer for mass scales < 3 M sun for the strong magnetic field case. This critical mass scale can be understood semi-analytically as the time scale of magnetic braking. We show that the anisotropy of the angular momentum transfer due to the presence of strong magnetic field changes the resultant angular momentum of the core only by a factor of two. We also find that the distribution of the angle between the direction of the angular momentum and the magnetic field is random even just before the first core formation. Our results also indicate that the variety of the angular momentum of core inherited from the difference of the phase of the initial turbulent velocity field could contribute to the diversity in size and other properties of protoplanetary disks recently reported by observations.

Facilitator
-Name: Kanji Mori
Comment: English