カテゴリー: 総研大コロキウム

May 7 Tue 10:00-11:30
太陽系小天体セミナー (Solar System Minor Body Seminar)
Zoom

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

May 8 Wed 15:30-16:30
NAOJ Science Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

May 10 Fri 15:30-16:30
NAOJ Seminar
hybrid; Large Seminar Room in Subaru Building and Zoom

詳細は下記からご覧ください。

=============== May 7 Tue===============

キャンパス：三鷹
セミナー名：太陽系小天体セミナー (Solar System Minor Body Seminar)
定例・臨時の別：定例
日時：　5月　7日（火曜日）10時00分～11時30分
場所：zoom
講演者：秋澤宏樹

世話人の連絡先
-名前：渡部潤一
備考：zoomでの参加

=============== May 8 Wed===============

Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Scheduled
Date and time：May 8, 2024 10:30-12:00
Place：Large Seminar Room in Subaru Building and Zoom

Speaker：Ryota Ichimura
Affiliation：SOKENDAI 4th year (D2) (Supervisor: Hideko Nomura, Akimasa Kataoka, Nanase Harada)
Title：The impact of Cosmic Rays on Carbon Isotope Fractionation of COMs in Star-Forming Cores

Speaker：Ryota Ikeda
Affiliation： SOKENDAI 4th year (D2) (Supervisor: Daisuke Iono, Masayuki Tanaka, Takuma Izumi)
Title：Resolving Luminous Submillimeter Galaxies

Facilitator
-Name：Yoshiaki Sato
Comment：Language: English

===============May 8 Wed==============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2023 May 8 (Wed.), 15:30-16:30 JST
Place: the large seminar room / Zoom (hybrid)

Speaker: Yukun Huang
Affiliation: CfCA, Division of Science
Title: A Rogue Planet Hypothesis for the Formation of the Trans-Neptunian Solar System – 太陽系外縁の形成におけるローグ惑星仮説 –
Abstract:
Over the past two decades, our knowledge of the Solar System’s Trans-Neptunian region (often called the Kuiper Belt) has been gradually increasing. Observational surveys have greatly expanded the inventory of Trans-Neptunian Objects (TNOs), which are distant icy bodies thought to be relics from the giant planet formation era. In the distant Kuiper Belt beyond 50~au, several striking features seem to challenge our previous understanding of the early Solar System: 1) a very large population of objects in distant mean-motion resonances with Neptune, 2) a substantial detached population that are not dynamically coupled with Neptune’s effects, and 3) the existence of three very-large perihelion objects, known as Sednoids. I will demonstrate in this talk, that a super-Earth-mass planet temporarily present in the Solar System (referred to as a ‘Rogue Planet’), is able to create all these structures in the distant Kuiper Belt. Such a planet would have formed in the giant planet region and gotten scattered to a highly-eccentric orbit with a few hundred au semimajor axis with a typical lifetime of
100 Myr. Additionally, when examining the past history of the three Sednoids, I surprisingly find that all their apsidal lines were tightly clustered at 200° exactly 4.5 Gyr ago. This “primordial orbital alignment”, if confirmed true, strongly argues for an initial event that imprinted this particular apsidal orientation on early detached TNO population, and the rogue planet model could potentially explain this new phenomenon.

Facilitator
-Name: Masamitsu Mori
Comment: English

===============May 10 Fri==============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：May 10 Fri, 2024 15:30-16:30
Place：Zoom/Large Seminar Room (hybrid)

Speaker：Dr. Athira Menon
Affiliation：Institute of Astrophysics of the Canary Islands

Title：Towards solving an old stellar puzzle: the origin(s) and fate(s) of blue supergiants

Abstract: The origin and fate of observed B-type blue supergiants (BSGs), has been a long-standing puzzle in stellar astrophysics. The majority of these stars are observed to be single (with no detectable companion), and populate the end of the main sequence (MS) and the Hertzsprung gap on the HR diagram. However, models of stars that are born alone, have found limited success in simultaneously explaining the measured physical and chemical properties of BSGs, thereby indicating that a different evolutionary channel may dominate their creation. In this talk, I will present novel models of stars that are born from the mergers of binaries containing giant stars and MS companions. To compare our models, we newly analysed a large sample of early B-type supergiants in the Large Magellanic Cloud (LMC) and derived their surface properties. Unlike classical single-star models, merger-born stars sustain their BSG status throughout their core He-burning phase and quite easily populate the traditional Hertzsprung gap. We find that the largest group of the observed sample are likely only born from mergers, a smaller second group may contain both born-alone stars and merger-born stars and the minority are likely MS single stars. Although supernova SN 1987A is the most famous explosion of a BSG, the rate of 87A-like events is lower than the observed number of BSGs. I will close the talk with possibilities of other transients and remnants that may be the final outcomes of the deaths of BSGs.

Facilitator
-Name：Takuma Izumi

April 24 Wed 10:30-12:00
SOKENDAI Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

April 24 Wed 15:30-16:30
NAOJ Science Colloquium
hybrid; Large Seminar Room in Subaru Building and Zoom

April 26 Fri 16:00-17:00
NAOJ Seminar
hybrid; Large Seminar Room in Subaru Building and Zoom

詳細は下記からご覧ください。

=============== April 24 Wed===============

Campus：Mitaka
Seminar：SOKENDAI Colloquium
Regularly Scheduled/Sporadic：Scheduled
Date and time：April 24, 2024 10:30-12:00
Place：Large Seminar Room in Subaru Building and Zoom

Speaker：Shun Hatano
Affiliation：SOKENDAI 3rd year (D1) (Supervisor: Masami Ouchi, Takashi Moriya, Yusei Koyama)
Title：Near-infrared Variability of Ultra/luminous Infrared Galaxies
Speaker：Itsuki Ogami
Affiliation：SOKENDAI 5rd year (D3) (Supervisor: Wako Aoki, Hisanori Furusawa, Miho N. Ishigaki)
Title：The Nature of the Stellar Halo in the Triangulum Galaxy

Facilitator
-Name：Yoshihiro Naito

Comment：Language: English

=============== April 24 Wed===============

Campus: Mitaka
Seminar: NAOJ Science Colloquium
Date and time: 2024 Apr. 24 (Wed.), 15:30-16:30 JST
Place: the large seminar room / Zoom (hybrid)

Speaker: Qiliang Fang
Affiliation: NAOJ (JSPS fellow)
Title: Inferring the evolution pathways and the explosion mechanism of core-collapse supernova through late-phase spectroscopy
Abstract:
Core-collapse supernovae (CCSNe) are considered as the final explosions of massive stars, following the depletion of the nuclear products in their cores. These catastrophe events are diverse in observation especially the chemical composition in the expelled material (ejecta), which implies varied mass-loss histories preceding the explosion. Despite over a century of discoveries, the mechanism responsible for the diversity in CCSNe, and its potential connection with the still-unresolved core-collapse process, is still a topic of active debate. In this talk, I will introduce the application of late-phase (nebular) spectroscopy of CCSNe to reveal these longstanding mysteries. Beginning with the fundamental concepts of CCSNe, I will provide an overview of the physical quantities that can be inferred from nebular spectroscopy. Next, I will demonstrate how the statistics analysis of nebular spectroscopy can be employed to constrain the properties of the progenitor, the dynamics of the ejecta, and their mutual relations. This investigation suggests massive stars leads to more aspheric and energetic explosions. Finally, I will introduce my future research plan, which aims to connect the diverse pre-SN activities discovered by recent transient surveys with the properties of their progenitors.

Facilitator
-Name: Hiroki Nagakura

Comment: English

===============April 26 Fri==============

Campus：Mitaka
Seminar：NAOJ Seminar
Regularly Scheduled/Sporadic：Regular
Date and time：April 26 Fri, 2024 16:00-17:00
Place：Zoom/Large Seminar Room (hybrid)

Speaker：Dr. Athira Menon
Affiliation：Institute of Astrophysics of the Canary Islands

Title：Towards solving an old stellar puzzle: the origin(s) and fate(s) of blue supergiants

Abstract: The origin and fate of observed B-type blue supergiants (BSGs), has been a long-standing puzzle in stellar astrophysics. The majority of these stars are observed to be single (with no detectable companion), and populate the end of the main sequence (MS) and the Hertzsprung gap on the HR diagram. However, models of stars that are born alone, have found limited success in simultaneously explaining the measured physical and chemical properties of BSGs, thereby indicating that a different evolutionary channel may dominate their creation. In this talk, I will present novel models of stars that are born from the mergers of binaries containing giant stars and MS companions. To compare our models, we newly analysed a large sample of early B-type supergiants in the Large Magellanic Cloud (LMC) and derived their surface properties. Unlike classical single-star models, merger-born stars sustain their BSG status throughout their core He-burning phase and quite easily populate the traditional Hertzsprung gap. We find that the largest group of the observed sample are likely only born from mergers, a smaller second group may contain both born-alone stars and merger-born stars and the minority are likely MS single stars. Although supernova SN 1987A is the most famous explosion of a BSG, the rate of 87A-like events is lower than the observed number of BSGs. I will close the talk with possibilities of other transients and remnants that may be the final outcomes of the deaths of BSGs.

Facilitator
-Name：Joten Okamoto