MENU

天文学教室 談話会

last-update:2026/04/23

今後の談話会

  第1840回 天文学教室談話会

2026年5月19日(火) 16:15-17:15 James Jackson (NRAO, USA)

Title: 

Abstract:

今後の予定

2026年5月26日(火) 16:15-17:15 金田 優香 (UTokyo)

2026年6月26日(金) 4限(?) Koutarou Kyutoku 久徳浩太郎 (Chiba University, Japan)

2026年7月28日(火) Ronan Kerr (The University of Toronto, Canada)

過去の談話会

  第1839回 天文学教室談話会

2026年4月21日(火) 16:15-17:15 

Title: 3D Models of AGB Stars: Convection, Pulsations, and Mass-Loss Processes

Speaker: Arief Ahmad (UTokyo)

Language: English

Abstract:

Stars on the asymptotic giant branch (AGB) represent a late stage of stellar evolution during which substantial mass loss enriches the interstellar medium, yet the physical mechanisms driving this process remain only partially understood. In particular, the interplay between pulsations, convection, and dust formation produces complex and time dependent behaviour that challenges simplified modelling approaches. Global three dimensional radiation hydrodynamics simulations, such as those computed with CO5BOLD, provide a framework in which convection and pulsations arise self consistently from the stellar interior, allowing these processes to be studied from first principles. In this seminar, I will present how such models provide physical insight into the origin and characterisation of pulsations, and discuss how their interaction with convection shapes the structure and variability of AGB atmospheres, ultimately enabling dust formation and mass loss through massive stellar winds.

  第1838回 天文学教室談話会

2026年4月16日(木) 15:00-16:00

Title: The long-term evolution of turbulent discs in high-redshift galaxies

Speaker: Joss Bland-Hawthorn (University of Sydney, Australia)

Language: English

Abstract:

Most disc galaxies go through an early epoch of being “gas rich,” an era that is being actively explored today through ALMA and JWST observations. This high gas-fraction phase got going much sooner (z > 3) than anticipated by cosmological N-body simulations. A new class of controlled (Nexus) simulations of these early times reveals that these turbulent discs have extraordinary properties. Unexpectedly, m=2,3 spiral arms, stellar and gaseous bars, even X-shaped/peanut bulges, all form under these conditions. The high gas content accelerates stellar migration and stabilizes the disc against buckling. Moreover, baryon sloshing driven by strong feedback gives rise to thick stellar discs, a likely origin of alpha-enriched thick stellar discs observed today. The sloshing gives rise to specific signatures that may already be observable in ALMA data. We discuss the implications of the new work on galaxy studies.

  第1837回 天文学教室談話会

2026年4月14日(火) 16:15-17:15

Title: Photon Counting CMOS Imaging Detectors for Optical and UV Astrophysics

Speaker: Don Figer (Rochester Institute of Technology, USA)

Language: English

Abstract:

NASA’s Habitable World Observatory (HWO) will observe faint sources in ultralow (photon-per-hour) backgrounds. In this talk, we present NASA-funded research to advance single-photon counting and radiation-tolerant CMOS detectors for NASA missions, in particular, those requiring optical/UV photon counting detectors. In the project, we will measure the performance of Fairchild Imaging large-format single photon counting and photon number resolving CMOS imaging detectors (HWK4123) before and after radiation that simulates the environment at L2. These detectors have very low capacitance sense nodes to produce a large voltage response to a single photon. In a predecessor project, we found that performance for a similar detector (QIS, Gigajot Technologies) is little-changed after exposure to 50 krad(Si). The dark current can be set to beginning-of-life levels with modest additional cooling, 4–6 K for an 11-year mission. The project seeks to minimize the transient and long-term effects of radiation in NASA missions and also to design a single photon counting and photon number resolving NIR detector with similar architecture.

  天文学教育研究センター談話会について

天文学教育研究センター談話会については、こちらをご覧ください。

  本郷キャンパスでの天文・宇宙物理関係のセミナーアナウンスについて

東大本郷キャンパスの天文・宇宙物理関連のセミナーをアナウンスする際は、
hongo-astrotalks (at-sign) astron.s.u-tokyo.ac.jp
をお使いください。 このアドレスにメールを出すと、以下のグループの構成員に展開されます。

  • 天文学教室
  • RESCEU
  • 物理学教室
    • 安東研究室
    • 宇宙理論研究室
    • 日下研究室
    • 馬場研究室
    • 山本研究室

幅広い関係者にメールが展開されることに留意して、多くの人が興味を 持ちそうなセミナー・教室談話会などのアナウンスにお使いください。

 

  過去の談話会