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