2023/11/13~2023/11/19

November  14 Tue 10:00-11:30 太陽系小天体セミナー zoom              


November  15 Wed 10:30-12:00 SOKENDAI Colloquium Large Seminar Room in Subaru Building and Zoom   


November 15 Wed 14:30-15:30 ALMA-J seminar Small seminar room in Subaru building (院生セミナー室) / Zoom (hybrid)


November 15 Wed 15:30-16:30 NAOJ Science Colloquium Zoom (full virtual style)


詳細は下記からご覧ください。

=============== November  14 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:11月14日(火曜日)10時00分~11時30分
場所:zoom
講演者:野上長俊

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

=============== November  15 Wed===============

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:November 15, 2023 10:30-12:00
Place:Large Seminar Room in Subaru Building and Zoom

Speaker: Yoshihiro Naito
Affiliation: SOKENDAI 2nd year (M2) (Supervisor: Hirohisa Hara. Ryoko Ishikawa, Joten Okamoto)
Title: Spectroscopic study of Alfvén waves in the upper chromosphere as an energy source of solar wind acceleration in coronal holes

Speaker: Yoshiaki Sato
Affiliation: SOKENDAI 2nd year (M2) (Supervisor: Noriyuki Narukage, Takashi Sekii, Masumi Shimojo)
Title: Evaluation of electron acceleration efficiency during solar flares using MHD+GCA Test-Particle simulation

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

=============== November 15 Wed==============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Nov 15th (Wed) 14:30-15:30
Place: Small seminar room in Subaru building (院生セミナー室) / Zoom (hybrid)
Speaker: Mengyuan Xiao
Affiliation: University of Geneva
Title: A new era of studying extremely dust-obscured massive galaxies in the early Universe with JWST and ALMA
Abstract:
Recent studies have unveiled the existence of extremely dust-obscured massive galaxies at z>3 and into the reionization epoch. This has significant implications for our understanding of early galaxy build-up and the cosmic star formation history. In this talk, I will discuss our recent findings on these galaxies with JWST FRESCO survey and GOODS-ALMA survey. In particular, I will present the advantages of JWST/spectroscopy in studying these galaxies. Based on the unprecedented imaging and spectroscopic data from the JWST FRESCO survey, we can systematically determine their spectroscopic redshifts, thus vastly improving constraints on their physical properties. In addition, I will show several extremely massive dusty galaxies at zspec > 5, that may challenge the current galaxy assembly models. I will discuss their ultra-massive properties, dust-obscured star formation rates, and the possibility of the existence of AGN. I will finish with some of our other recent discoveries and future plans for extremely dust-obscured massive galaxies.

Organizers: Gianni Cataldi , Hiroshi Nagai

=============== November 15 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Nov. 15 (Wed.), 15:30-16:30
Place: Zoom (full virtual style)

Speaker: Aya Bamba
Affiliation: The University of Tokyo
Title: X-ray study of supernova remnants, the origin of diversity in the universe

  • 多様性の源: 超新星残骸のX線研究 –
    Abstract:
    Supernova remnants (SNRs) supply thermal and kinetic energy, heavy elements, and high energy particles (cosmic rays) into the space, so they are the origin of diversity of the universe. Shocked plasma is heated up to 1-10 MK, and emits thermal X-rays with characteristic X-ray lines from heavy elements, thus X-ray observations are an ideal tool how SNRs play their role in the universe. In this talk, I will introduce several recent topics of SNR science – progenitor science and shock physics.
    Such a study needs excellent energy resolution in the X-ray band in order to resolve emission lines from minor elements and their Doppler motion. On this September, we succeeded to launch XRISM with H2A rocket.
    I also introduce how XRISM is launched and what XRISM will achieve on SNR science.

Facilitator
-Name: Hiroki Nagakura
Comment: English

2023.11.6~2023.11.12

  

November  6  Mon 13:30-15:00 Solar and Space Plasma Seminar hybrid; Subaru Building / Insei Seminar Room or Zoom              


November  7 Tue  9:00-12:00   

SOKENDAI Doctoral Thesis Preliminary Evaluation 総研大博士学位論文予備審査会
Lecture Room and Zoom&Large Seminar Room and Zoom       


November 7 Tue 10:00-11:30   太陽系小天体セミナー zoom


November 8 Wed 10:30-12:00   SOKENDAI Colloquium Large Seminar      Room in Subaru Building and Zoom


November 10 Fri 16:00-17:00   NAOJ Seminar Zoom/Large Seminar Room(hybrid)


詳細は下記からご覧ください。

=============== November  6 Mon===============

Campus: Mitaka
Seminar: Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic: Scheduled
Date and time:6th November (Mon), 13:30-15:00
Place: hybrid; Subaru Building / Insei Seminar Room or Zoom
Speaker:Brigitte Schmieder
Affiliation:Observatoire de Paris, LESIA, France
Title:Solar jets observed by IRIS and high spatial resolution ground-based telescopes
Abstract:Solar jets have been observed over a large range of temperatures and wavelengths, from Hα for more than 50 years, to X-rays since the launch of the Yohkoh satellite in 1991. Several characteristics have been derived about their velocities, their rates of occurrence, and their relationship with CMEs. However, the initiation mechanism of jets, e.g. emerging flux, flux cancellation, or twist, is still debated. The high spatial resolution of IRIS and ground-based telescopes (SST,GST) allows us to make a step forward in understanding the relationship of cool and hot jets. Combining IRIS data with vector magnetograms we were able to study the magnetic environment favorable for the occurrence of jets. We searched for possible sites of reconnection by analyzing the magnetic topology.
We found that the magnetic reconnection site can be located at a null point in the corona as well as in a bald patch region forming a current sheet. The IRIS spectra provide evidence of bilateral flows at the reconnection site, due to a transfer of twist from a flux rope to the jet. We detected the presence of cool plasma and hot plasma during the jet formation, including ejections of blobs with speeds reaching super Alfvénic flows of the order of 300 km/s.

Facilitator
-Name:Takayoshi oba
Comment:in English

=============== November  7 Tue===============

Campus:Mitaka
Seminar:SOKENDAI Doctoral Thesis Preliminary Evaluation 総研大博士学位論文予備審査会
Regularly Scheduled/Sporadic:Sporadic
Date and time:November 7, 2023 9:00~12:00

Place 1:Lecture Room and Zoom

Speaker:
9:00-9:40 Raiga Kashiwagi
Title:Instability and Evolution of Shocked Clouds Formed by Collisions between Filamentary Molecular Clouds

Speaker:
10:00-10:40 Yui Kasagi
Title:Unveiling Atmospheric Features of Faint Substellar Companions from High-Resolution Near-Infrared Spectra

Speaker:
11:00-11:40 Takaho Masai
Title:A Study on the Design of Receiver Optics and Waveguide Components Towards High-Performance (Sub)millimeter Wave Multibeam Receivers

Place 2:Large Seminar Room and Zoom

Speaker:
9:00-9:40 Rikuto Omae
Title:Probing the Magnetic Fields of Distant Galaxies to Unravel the Evolution of Galactic Magnetic Fields

Speaker:
10:00-10:40 Yuta Tashima
Title:Elucidation of Galactic Magnetic Field Structure by Pseudo-Observation Focusing on Depolarization

Facilitator
-Name:Nozomu Tominaga, Hideyuki Kobayashi, Natsuko Fujii (Graduate Student Affairs Unit)

=============== November 7 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:11月7日(火曜日)10時00分~11時30分
場所:zoom
講演者:佐藤幹哉

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

=============== November 8 Wed==============

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:November 8, 2023 10:30-12:00
Place:Large Seminar Room in Subaru Building and Zoom

Speaker: Shunsuke Sasaki
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Tomoya Takiwaki, Mami Machida, Takashi Moriya)
Title: Developing “1D+” simulation of core-collapse supernovae

Speaker: Raiga Kashiwagi
Affiliation: SOKENDAI 5th year (D3) (Supervisor: Kazunari Iwasaki, Tomoya Takiwaki, Doris Arzoumanian)
Title: Instability and Evolution of Shocked Clouds Formed by Collisions between Filamentary Molecular Clouds

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

=============== November 10 Fri==============

Campus:Mitaka
Seminar:NAOJ Seminar
Regularly Scheduled/Sporadic:Regular
Date and time:November 10, 2023 16:00-17:00
Place:Zoom/Large Seminar Room (hybrid)

Speaker:Prof,Yasuhito Sekine
Affiliation:Earth-Life Science Institute

Title:Detection of phosphate in Enceladus’ ocean and comparative chemical evolution in the Solar System
Abstract:
Planetary habitability can be defined as a planetary-scale system that can develop and sustain ingredients of life—liquid water, organics, and energy—over geological time. In this regard, Enceladus possesses a habitable world beneath the icy shell. This moon has a global subsurface ocean interacting with a rocky core, and a wide variety of organic matter and chemical energy supported by hydrothermal activities are available. Among the major bioessential elements for Earth’s life, phosphorus (P) is usually the least abundant in natural aqueous systems and has been a limiting nutrient of primary productivity over Earth’s history. It has been unknown whether this essential element is available in Enceladus. Here we report the discovery of phosphate in ice grains emitted by Enceladus based on the analysis by Cassini’s Cosmic Dust Analyser. Our observational results are evidence that phosphorus is readily available in Enceladus’ ocean, with anomalously high concentrations–at least 100 times higher than Earth’s oceans. To understand the causative mechanism of the enrichment of phosphate, we performed hydrothermal experiments and geochemical modeling. We find that alkaline (pH ~10) and carbonate-rich aqueous environments are essential for the phosphate enrichment, where calcium phosphate minerals are thermodynamically unstable compared to calcium carbonate minerals. Such alkaline carbonate-rich aqueous environments are commonly achieved in icy ocean worlds beyond the CO2 snowline of the Solar System. Phosphate could have been also enriched in similar alkaline carbonate-rich aqueous environments on early Earth, where earliest life on Earth might have utilized phosphorus as components of its building materials.

Facilitator
-Name:Okamoto, Takenori


2023.10.30-2023.11.5


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


2023/10/16~2023/10/22

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

2023.10.9-2023.10.15

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


Oct 11 Wed    13:30-15:00 Solar and Space Plasma Seminar   hybrid; Subaru Building / Insei Seminar Room or Zoom


Oct 11 Wed    14:00-15:00   Tea Talk 輪講室(+Zoom)


Oct 11 Wed    14:30-15:30    ALMA-J seminar hybrid (ROOM102 in ALMA building and ZOOM)


Oct 11 Wed    15:30-16:30    NAOJ Science Colloquium Zoom / the large seminar room (hybrid)


Oct 13 Fri   16:00-17:00 NAOJ Seminar zoom/ Large seminar room in Subaru Building


詳細は以下をご覧下さい。

=============== October 10 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10日(火曜日)10時00分~11時30分
場所:zoom
講演者:秋澤宏樹

Abstract:『COMETS III』より、著者による先行公開されている2つの章、
「彗星大気の化学」
https://www.research.ed.ac.uk/en/publications/chemistry-of-comet-atmospheres
「遠隔観測による彗星核の物理・表面特性」
https://arxiv.org/abs/2304.09309
の内容を紹介したいと思います。

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 11 Wed===============

Campus: Mitaka
Seminar: Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic: Scheduled
Date and time:11th Oct (Wed), 13:30-15:00
Place: hybrid; Subaru Building / Insei Seminar Room or Zoom
Speaker: Stanislav Gunar
Affiliation:Astronomical Institute of the Czech Academy of Sciences
Title:What is important for robust inversions of spectroscopic observations of chromospheric and coronal structures?
Abstract:In this presentation, we will discuss what is hidden behind the term “robust spectroscopic inversions” and what we need to achieve them. We will focus on the use of UV spectral data, such as the Lyman line series and the Mg II h&k lines.

There are several necessary ingredients needed to produce high-fidelity spectroscopic inversions. The first is high-resolution multi-wavelength observations. The second are realistic radiative transfer models encompassing dominant processes forming the observed spectra. The third component is sophisticated inversion methods that allow us to find a realistic fit between the observed and synthetic spectra. And there is another necessary component – a good understanding of all important boundary conditions.

We will demonstrate the importance of boundary conditions on the example of the so-called incident radiation. This is the radiation coming from the solar surface, which illuminates chromospheric and coronal structures, such as prominences or spicules. We will show that variations in this boundary condition have a strong impact on the shape and intensity of Lyman lines and the Mg II h&k lines. This impact is then responsible for significantly different outcomes of spectroscopic inversions.

Facilitator
Name:Takayoshi oba
Comment:in English

=============== October 11 Wed===============

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:10/11(水)14:00~15:00
場所:輪講室(+Zoom)
講演者:渡部 潤一
所属:天文情報センター
タイトル:APRIM2023の顚末記

世話人の名前:藤田登起子

=============== October 11 Wed===============

Campus: Mitaka
Seminar: ALMA-J seminar
Date and time: Oct 11th (Wed) 14:30-15:30
Place: hybrid (ROOM102 in ALMA building and ZOOM)
Speaker: Tetsu Kitayama
Affiliation: Toho University
Title: High-resolution measurements of the Sunyaev-Zel’dovich effect toward galaxy clusters
Abstract:
The Sunyaev-Zel’dovich effect (SZE) provides a unique probe of cosmic plasma up to high redshifts. We first review briefly the progress of high-resolution SZE observations over the past two decades. We then present the measurements made by the Atacama Large Millimeter/submillimeter Array (ALMA); we have obtained SZE images toward four galaxy clusters with 5″ resolution, while retaining extended signals out to 40″. We also discuss implications of these results on the evolution of galaxy clusters as well as prospects for further SZE measurements.

=============== October 11 Wed===============

Campus:Mitaka
Seminar:NAOJ Science Colloquium
Regularly Scheduled/Sporadic:Every Wednesday Date and time:2023 Oct. 11, 15:30-16:30
Place:Zoom / the large seminar room (hybrid)

Speaker:Daichi Kashino
Affiliation:NAOJ
Title:Witnessing Galaxies Reionizing the Intergalactic Medium with JWST
Abstract:
Cosmic reionization is the last major phase transition of the universe, occurring in the first billion years after the Big Bang.
Understanding this process is one of the pivotal goals in modern astrophysics. The commissioning of JWST heralded a new era in investigating the roles of galaxies in reionizing the intergalactic medium, thanks to its unprecedented high sensitivity and dispersing power in near infrared.

In the presentation, I will present early results from our ongoing EIGER (Emission-line galaxies and Intergalactic Gas in the Epoch of
Reionization) survey, a JWST/NIRCam WFSS campaign in the fields of luminous z>6 quasars. The existence of these background quasars enables us to determine the ionization condition along their lines of sight from analysis of the high signal-to-noise quasar spectra. The primary objective of the project is to characterize the cross correlation between galaxies (as pinpointed by JWST) and the IGM conditions during the tail end of the epoch of reionization. In the first quasar field, we confirmed roughly 150 [OIII]5008-emitting galaxies over the redshift range of z=5.3–6.9. Through analyzing the distribution of these galaxies and the transmission spectrum of this corresponding quasar, we identified individual spatial coincidence between the groups of galaxies and highly ionized regions, as well as a mean excess IGM transmission in both Lyman-alpha and Lyman-beta around ~6 cMpc away from the galaxies at z~6. This is interpreted as direct evidence of local reionization by galaxies — indicating that we are witnessing galaxies reionizing the surrounding IGM. I may also showcase further preliminary results from other quasar fields currently being analyzed.

Facilitator
Name:Haruka Kusakabe
Comment:English

=============== October 13 Fri===============

Campus:Mitaka
Seminar:NAOJ Seminar
Regularly Scheduled/Sporadic:Regularly Scheduled Date and time:2023 Oct 13, 16:00-17:00
Place:zoom/ Large seminar room in Subaru Building

Speaker: Cristian Eduard Rusu, PhD
Affiliation: Axelspace Corporation
Title: Opportunities and Challenges for Space Observations with Commercial Satellites
Abstract:Over the past decade, the number of satellites launched into orbit for commercial
purposes has increased exponentially. Nonetheless, these have had virtually no usage for
astronomical observations, due to the still prohibitive cost of launching large mirrors and
achieving scientific-level tolerances. In recent years however, governments as well as private
companies have become interested in Space Situation Awareness, or gaining insights from
optical monitoring from space of artificial satellites and space debris as faint as the 14th magnitude.
This renewed interest in space observations has the potential of reducing the cost of dedicated
astronomical satellites and bringing them within the reach of commercial companies.
I will explore these topics as experienced from the point of view of Axelspace, a Japanese commercial
satellite manufacturer and provider of satellite imagery.

Facilitator
-Name:Moriya, Takashi