2023.12.25-2024.1.7

December 26 Tue 16:00-17:00 NAOJ Seminar
Large Seminar Room in Subaru Building and Zoom(hybrid)


December 27 Wed 10:30-12:00 SOKENDAI Colloquium
Large Seminar Room in Subaru Building and Zoom (hybrid)


詳細は下記からご覧ください。

=============== December 26 Tue ===============

Campus:Mitaka
Seminar:NAOJ Seminar
Regularly Scheduled/Sporadic:Sporadic
Date and time:December 26, 2023 16:00-17:00
Place:Zoom/Large Seminar Room (hybrid)

Speaker:Prof. Daniel Jontof-Hutter
Affiliation:University of the Pacific
Title:Three-body resonances in Multitransiting Exoplanetary Systems
Abstract:Planet formation models with convergent migration show that planet pairs are easily trapped in mean motion resonances. Yet in Kepler’s multi-planet systems, orbital period ratios near resonance are rare.
Furthermore, those pairs with commensurate orbital period ratios, the measurement uncertainties of orbital eccentricities make it difficult to show that any planet pair is in libration.
Three-body resonances, however, may be easier to identify. Several systems have been shown to be in 3-body libration. Using transit timing data, we explore dynamical simulations of Kepler systems that are potentially in three-body resonances.
We further search for three-body resonances among all triples within the Kepler dataset, in search of additional systems in libration. Finally, we estimate the fraction of planetary systems with three-body resonant chains.

Facilitator
-Name:Shinobu Ozaki

=============== December 27 wed===============

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:December 27, 2023 10:30-12:00
Place:Large Seminar Room in Subaru Building and Zoom

Speaker: Ryota Ikeda
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Daisuke Iono, Masayuki Tanaka, Takuma Izumi)
Title: Study of spatial extent and haloes of [CII] line emission in star-forming galaxies at z=4-6

Speaker: Itsuki Ogami
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Wako Aoki, Hisanori Furusawa, Miho N. Ishigaki)
Title: Probing the stellar halo in M33 using Subaru/HSC

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

2023.12.18-2023.12.24

Dec 19 Tue 10:30-12:00 Solar and Space Plasma Seminar
Central Building (North) / 310, Subaru Building / Insei Seminar Room and Zoom(hybrid)


December 20 Wed 10:30-12:00 SOKENDAI Colloquium
Large Seminar Room in Subaru Building and Zoom (hybrid)


December 20 Wed 15:30-16:30 NAOJ Science Colloquium
the 3F seminar room in Instrument Development Building No.3 and Zoom (hybrid)

詳細は下記からご覧ください。

=============== December 19 Tue ===============

Campus: Mitaka
Seminar: Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic: Scheduled
Date and time:19th December (Tue), 10:30-12:00
Place: hybrid; Central Building (North) / 310, Subaru Building / Insei Seminar Room, or Zoom
Speaker:Takato Tokuno
Affiliation:University of Tokyo (D1 student)
Title:Spin evolution of the Sun and low-mass stars
Abstract:The spin rate of a low-mass star, including the Sun, is crucial
because it interacts with magnetism through the dynamo effect. Since
magnetised stellar wind transports the angular momentum from a star
(‘magnetic braking’), the star basically spins down. The spin-down of
solar-type stars has been studied by comparison between theoretical
modelling and observed stellar properties. Although the previous model
can explain observed basic trends, there remain unsolved problems. In
this seminar, I will review the current study of stellar spin-down,
including my paper.

Facilitator
-Name:Akiko Tei

Comment:in English

=============== December 20 wed===============

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:December 20, 2023 10:30-12:00
Place:Large Seminar Room in Subaru Building and Zoom

Speaker: Kousuke Ishihara
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Fumitaka Nakamura, Masao Saito, Patricio Sanhueza)
Title: Observational study of the fragmentation process in nearby star-forming regions

Speaker: Yui Kasagi
Affiliation: SOKENDAI 55h year (D3) (Supervisor: Takayuki Kotani, Saeko Hayashi, Wako Aoki)
Title: Unveiling atmospheric features of an L dwarf observed with REACH/Subaru

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

=============== December 20 wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Dec. 20 (Wed.), 15:30-16:30
Place: the 3F seminar room in Instrument Development Building No.3 / Zoom (hybrid)

Speaker: GUIMARÃES Gabriel
Affiliation: The University of Tokyo
Title: Chaotic Diffusion: Importance, approaches and consequences
Abstract:
Regular motion in the dynamical systems might now be regarded as the odd phenomena instead of chaotic ones. That is because chaotic motion seems to take place more widely and commonly than periodic ones, and in Celestial Mechanics it could be no different.
Still, it is not uncommon to characterise orbits of asteroids and comets that are clearly stable as chaotic ones and vice versa. That is because of Chaotic Diffusion, which is responsible to drive dynamical systems from a regular state to a chaotic one.
Nonetheless, the onset of chaos — as well as the effective “chaoticity” of an orbit — might not be immediate nor evident, pronouncing themselves in distinct timescales, sometimes larger than the system’s own lifetime.
Such cases, those of “stable” or “weak” chaos, chaotic diffusion is thought to play a significant role in shaping and sculpting our Solar system and other extrasolar counterparts orbital architecture.
In this presentation, I will explain a bit about chaos, contextualize it within the realms of celestial mechanics and planet formation, present tools for quantification of chaotic diffusion and how to use them to estimate instability times that are comparable to observed/simulated ones without the need to intensive and extensively making use of computational resources nor sophisticated mathematical models.

Speaker: Tomohiro Yoshida
Affiliation: NAOJ (D1)
Title: The First Spatially-resolved Detection of 13CN in a Protoplanetary Disk and Evidence for Complex Carbon Isotope Fractionation
Abstract:
Recent measurements of carbon isotope ratios in both protoplanetary disks and exoplanet atmospheres have suggested a possible transfer of significant carbon isotope fractionation from disks to planets. For a clearer understanding of the isotopic link between disks and planets, it is important to measure the carbon isotope ratios in various species. In this talk, we present a detection of the 13CN N = 2−1 hyperfine lines in the TW Hya disk with the Atacama Large Millimeter/submillimeter Array.
This is the first spatially-resolved detection of 13CN in disks, which enables us to measure the spatially resolved 12CN/13CN ratio for the first time. We conducted non-local thermal equilibrium modeling of the 13CN lines in conjunction with previously observed 12CN lines to derive the kinetic temperature, H2 volume density, and column densities of 12CN and 13CN. The H2 volume density is found to range between (4 − 10) ×
10^7 cm−3, suggesting that CN molecules mainly reside in the disk atmosphere. The 12CN/13CN ratio is measured to be ~70 at 30 < r < 80 au from the central star, which is similar to the 12C/13C ratio in the interstellar medium. However, this value differs from the previously reported values found for other carbon-bearing molecules (CO and HCN) in the TW Hya disk. This could be self-consistently explained by different emission layer heights for different molecules combined with preferential sequestration of 12C into the solid phase towards the disk midplane. This study reveals the complexity of the carbon isotope fractionation operating in disks.

Facilitator
-Name: Kanji Mori

Comment: English

2023.12.11-2023.12.17

December 12 Tue 10:00-11:30 太陽系小天体セミナー
Zoom


December  13 Wed 10:30-12:00 SOKENDAI Colloquium
Large Seminar Room in Subaru Building and Zoom (hybrid)


December  13 Wed 15:30-16:30 NAOJ Science Colloquium
Large Seminar Room in Subaru Building and Zoom (hybrid)

詳細は下記からご覧ください。

=============== December  12 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:12月12日(火曜日)10時00分~11時30分
場所:zoom
講演者:古荘玲子

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

=============== December  13 wed===============

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:December 13, 2023 10:30-12:00
Place:Large Seminar Room in Subaru Building and Zoom

Speaker: Shun Hatano
Affiliation: SOKENDAI 2nd year (M2) (Supervisor: Masami Ouchi, Yusei Koyama, Takashi Moriya)
Title: Supermassive black holes at high redshifts explored with James Webb Space Telescope

Speaker: Shun Ishigami
Affiliation: SOKENDAI 3rd year (D1) (Supervisor: Hirohisa Hara, Yukio Katsukawa, Masahito Kubo)
Title: Estimating the filling factor of coronal loops using EUV spectroscopic data

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

=============== December  13 wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Dec. 13 (Wed.), 15:30-16:30
Place: the large seminar room / Zoom (hybrid)

Speaker: Kensuke Kakiuchi
Affiliation: The University of Tokyo
Title: MHD Simulation of The Inner Galaxy with Radiative Cooling and Heating
Abstract:
Magnetic field is supposed to play a key role in the interstellar gas of the Galactic Center region (inner Galactic Bulge region).
Observations show that the strength of the magnetic field within the central few hundred parsecs of the Galaxy is stronger than in the Galactic disk region, and its magnetic energy is comparable poor even surpasses the thermal and kinetic energy of the interstellar gas.
Therefore, it is essential to study the role of the magnetic field to understand the behavior of the interstellar gas in the Galactic center region.
In this talk, we will present the results of 3D global magnetohydrodynamical simulations in the Galactic center region. A notable distinction from previous simulations is the inclusion of radiative cooling and heating effects. We found the formation of a mid-latitude low-plasma beta zone (dominated by magnetic field pressure), which would not have appeared in the model without radiative heating and cooling. While the thermal energy of the interstellar gas is lost because of radiative heating and cooling effects, the magnetic energy is independent of this direct effect and can contribute to the thickness that supports the interstellar gas clouds above the Galactic plane.In fact, it is difficult to explain the thickness of gas clouds in the Galactic center using only gas pressure scale heights, suggesting that the contribution of the magnetic field is important as an interpretation of this thickness.

Facilitator
-Name: Doris Arzoumanian

Comment: English

2023.12.4-2023.12.10

December 5 Tue 10:00-11:30 太陽系小天体セミナー
Zoom


December  6 Wed 10:30-12:00 SOKENDAI Colloquium
Large Seminar Room in Subaru Building and Zoom (hybrid)


December  6 Wed 11:00-12:00 Tea Talk
Zoom


December  6 Wed 15:30-16:30 NAOJ Science Colloquium
Large Seminar Room in Subaru Building and Zoom (hybrid)


December  8 Fri 16:00-17:00 NAOJ Seminar
Large Seminar Room in Subaru Building and Zoom (hybrid)

詳細は下記からご覧ください。

=============== December  5 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:12月5日(火曜日)10時00分~11時30分
場所:zoom
講演者:渡部潤一

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

=============== December  6 wed===============

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:December 6, 2023 10:30-12:00
Place:Large Seminar Room in Subaru Building and Zoom

Speaker: Abdurrahman Naufal
Affiliation: SOKENDAI 4th year (D2) (Supervisor: Yusei Koyama, Masayuki Tanaka, Yuichi Matsuda)
Title: Searching for quiescent galaxies in the Spiderweb protocluster with HST grism observation

Speaker: Takaho Masai
Affiliation: SOKENDAI 55h year (D3) (Supervisor: Alvaro Gonzalez, Yoshinori Uzawa, Takafumi Kojima)
Title: The Design of Frequency Independent Optics for (Sub)Millimeter Wave Multibeam Receivers

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

=============== December  6 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:12/6(水)11:00~12:00
場所:Zoom
Speaker: Séamus Duffy, Research Student, SOKENDAI
Title: Science Outreach in Ireland: Science Education at Birr Castle with I-LOFAR
Abstract: This tea-talk will talk a little bit about Ireland, and also about outreach there, broaching topics such as: who we target, how we target them, what activities and projects do we run, and adapting to Covid and a post-Covid world.

Bio: Séamus Duffy is a current research student at NAOJ working with the SCExAO team, focusing on applications of machine learning and AI to astronomy.
He originally came to Japan in 2017 and worked as an English teacher in Tokyo, where he stayed for four years before returning to Ireland in 2020. In Ireland he worked with the Technological University of the Shannon, Trinity College Dublin, and Dublin Institute for Advanced Studies as the education and engagement manager for the I-LOFAR project at Birr Castle, home of the Leviathan telescope. I-LOFAR is the Irish installation in the low frequency array, a radio telescope network which cover most of the European continent. He has a huge passion for teaching, outreach and inspiring younger minds to get involved with astronomy. During his time in outreach he worked to educate about I-LOFAR and the science being conducted at the telescope to the local population of Birr, local schools, businesses, and government officials. He was particularly interested in conducting outreach in a post-covid environment and utilising online and digital spaces for outreach programmes.

世話人の連絡先:
-名前:藤田登起子

=============== December  6 wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Dec. 6 (Wed.), 15:30-16:30
Place: the large seminar room / Zoom (hybrid)

Speaker: Moka Nishigaki
Affiliation: NAOJ (D1)
Title: Uncovering the Chemical Evolution of Galaxies from z=0–5 using the UniverseMachine
Abstract:
Cosmic baryon cycling is pivotal to galaxy evolution, and the amount of metals present in galaxies’ ISMs provides a key window into the gas cycling process. Recent JWST metallicity measurements and constraints on galaxy ISM masses have made it possible to recover the chemical evolution history of galaxies. In this talk, I present a novel empirical model that infers the average metallicity evolution of galaxies from redshift z=5 to z=0. Anchored in the UniverseMachine
(Behroozi+19) framework, our model converts observations of gas-phase metallicities across z=0—5 and galaxy ISM masses into constraints on the ISM return fraction, a key parameter quantifying the recycling of metals into the ISM versus expulsion into the CGM. I will show the initial results on how the ISM return fraction changes with mass and redshift.

Speaker: Xingqun Yao
Affiliation: Beihang University
Title: Neutrino Mass Hierarchy from Supernova Nucleosynthesis of Light Elements and the Roles of Unstable Nuclei
Abstract:
The origin of neutrino mass and mass hierarchy is one of the biggest unanswered questions in physics. In this talk I propose an astrophysical method so that the supernova (SN) ν-process nucleosynthesis, which is consistent with the mass hierarchy constrained from various ν-oscillation experiments, should provide independent observational signals of nucleosynthetic products in the specific nuclei such as 138La, 19F, 7Li, 11B and others (so-called ν nuclei) through the ν-flavor oscillation due to the MSW matter effect and the effect of collective oscillation [1].
Core-collapse SNe emits a huge number of neutrinos which bring valuable observational information on how the neutrinos propagate through the high-density matter and change their flavors and how explosive nucleosynthesis occurs. We found that the still unknown mass hierarchy is imprinted in the nucleosynthetic products of ν-nuclei [1,2]. In this talk, I will discuss the mechanism of SN ν-process nucleosynthesis and try to constrain the mass hierarchy by comparing our theoretical prediction of nuclear abundances and observed values in the meteorites and spectrascopy study. Among the calculated results, the abundance ratios of 11B/138La and 19F/16Oprovide exclusively sensitive probes to neutrino mass hierarchy [1]. These ratios are also influenced by the mass cut during the ejection phase of SN materials. These facts provide valuable quantitative tools to constrain the mass hierarchy through precise measurements of nuclear abundances of these ν-nuclei in SiC-X pre-solar grains and comprehensive studies of solar-system abundances.

Facilitator
-Name: Haruka Kusakabe
Comment: English

=============== December  8 Fri==============

Campus:Mitaka
Seminar:NAOJ Seminar
Regularly Scheduled/Sporadic:Regular
Date and time:December 8, 2023 16:00-17:00
Place:Zoom/Large Seminar Room (hybrid)

Speaker:Prof. Cecilia Lunardini
Affiliation:Arizona State University

Title:Neutrinos and gravity: multimessenger scenarios
Abstract:Multimessenger astronomy is developing rapidly, and neutrinos are major players in its vast landscape. It is hoped that, in the near future, experimental and theoretical developments will lead to the detection of neutrinos and gravitational waves from the same class of source. I discuss possible scenarios, involving neutrinos and gravitational waves from core collapse supernovae, and from binary mergers of matter-rich compact objects (for example, two neutron stars). I will also discuss tidal disruption events, where a star is torn apart and eventually accreted by a supermassive black hole. These events, which produce flares at infrared, optical and X-ray wavelengths, are sources of sub-Hz gravitational waves, and could emit very high energy neutrinos and cosmic rays. Emphasis will be placed on the feasibility and physics potential of future observations of neutrinos and other messengers from these diverse classes of emitters.

Facilitator
-Name:Shinobu Ozaki

2023.11.27-2023.12.3

November 28 Tue 10:00-11:30 太陽系小天体セミナー zoom              


November 29 Wed 10:00-12:00 SOKENDAI Colloquium Large Seminar Room in Subaru Building and Zoom (hybrid)


November 29 Wed 15:30-16:30 NAOJ Science Colloquium Large Seminar Room in Subaru Building and Zoom (hybrid)


詳細は下記からご覧ください。

=============== November  28 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28日(火曜日)10時00分~11時30分
場所:zoom
講演者:土屋智恵

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  29 Wed===============

Campus:Mitaka
Seminar:SOKENDAI Colloquium
Regularly Scheduled/Sporadic:Regular
Date and time:November 29, 2023 10:00-12:00
Place:Large Seminar Room in Subaru Building and Zoom

Speaker: Seiya Imai
Affiliation: SOKENDAI 1st year (M1) (Supervisor: Masayuki Tanaka, Yusei Koyama, Kiyoto Yabe)
Title: Search for extreme emission line galaxies at 1<z<3 using Subaru/Hsc

Speaker: Rikuto Omae
Affiliation: SOKENDAI 55h year (D3) (Supervisor: Mami Machida, Masami Ouchi, Kazuhiro Hada)
Title: Probing the Magnetic Fields of Distant Galaxies to Unravel the Evolution of Galactic Magnetic Fields

Speaker: Yuta Tashima
Affiliation: SOKENDAI 5th year (D3) (Supervisor: Mami Machida, Fumitaka Nakamura, Tomoya Takiwaki)
Title: Elucidation of Galactic Magnetic Field Structure by Pseudo-Observation Focusing on Depolarization

Facilitator
-Name:Matsuda, Graduate Student Affairs Unit

=============== November 29 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 Nov. 29 (Wed.), 15:30-16:30
Place: the large seminar room / Zoom (hybrid)

Speaker: Yoko Oya
Affiliation: Kyoto University
Title: Physical Structures Traced by Chemical Diagnostics in Disk-Forming Regions of Young Low-Mass Protostellar Sources
Abstract:
To understand the origin of the Solar system, the physical/chemical evolution along the star/planet formation is a key issue. With the advent of ALMA, extensive observational studies have revealed that both the physical structure and the chemical composition drastically change during the disk formation around protostars. Furthermore, it has been found that molecular distributions are sensitive to changes in the physical conditions. Some kinds of molecular lines are therefore prospected to work as ‘molecular markers’ to selectively highlight particular structures of disk forming regions.
Specifically, sulfur-bearing species have empirically been good tracers; the kinematic structures of the circummultiple structure, the circumstellar disk, and the outflow lobes are traced by the OCS, H2CS, and SO emission, respectively, in a young low-mass protostellar source IRAS 16293-2422 Source A. The gas in its circummultiple structure was found to keep falling toward its periastron even beyond its centrifugal radius, which is often assumed to be the outer edge of a Keplerian disk.
Angular momentum of the gas is the essential topic to understand the structure formation. The chemical diagnostics with the aid of the molecular markers can be a helpful tool to tackle with the redistribution of the angular momentum among the disk/envelope and outflow structures. Conversely, detailed physical characterization is essential to elucidating the chemical evolution occurring there.

Facilitator
-Name: Masamitsu Mori

Comment: English