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