談話会 | 2026年度

定例の場合
・金曜日午後4時～5時（毎週行なうわけではありません）
・理学研究科4号館 5階 504号室（宇宙物理学教室講義室）
という時刻・場所で行なっています。 談話会でのトークを考えていらっしゃる方は、どの教室スタッフにでも良いので、コンタクトをお願いします。

世話人 Host: Herman Lee (email: herman_at_kusastro.kyoto-u.ac.jp)

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第669回
Speaker: Jonay I. Gonzalez Hernandez (Instituto de Astrofísica de Canarias)
Date: 6/9 Tuesday
Time: 13:30 – 15:00
Place: Room 504 seminar room, building 4
Language: English
Title: TBD
Abstract: TBD

第668回
Speaker: Erik Petigura (UCLA)
Date: 5/22 Friday
Time: 16:00 – 17:00
Place: Room 504 seminar room, building 4
Language: English
Title: Emerging boundaries in the planet formation process
Abstract: The eight planets in the solar system fall neatly into three main categories: rocky terrestrials, hydrogen-dominated Jovians, and ice giants. These planet classes reflect different formation environments, processes, and timescales. Extrasolar planets, in contrast, span a continuum of sizes, masses, and orbit. They demand a richer taxonomy. Recently, large studies of the orbital eccentricities of transiting exoplanets have revealed new dividing lines in the planet formation process. Close-in planets larger than Neptune form according to very different pathways compared to their smaller counterparts. At the same time, new synergies involving RVs, direct imaging, and astrometry are beginning to illuminate the boundaries between the most massive planets (formed by core accretion) and the least massive brown dwarfs (formed by direct collapse). Surprisingly, this empirical boundary occurs well below the deuterium burning limit. Studies like this offer a preview of the types of insights we can look forward to with the upcoming release of Gaia DR4 in December of this year, which will dramatically expand our census of giant planets and brown dwarfs.

第667回
Speaker: Raphael Hirschi (Keele University)
Date: 4/13 Monday
Time: 9:30 – 10:30
Place: Science Seminar house
Language: English
Title: Predicting the evolution and fate of massive stars in 1 and 3D
Abstract: In this colloquium, I will start by briefly reviewing the importance of stars in the Universe. I will then discuss how we can re-create stars on computers using a range of simulations using a few hours on a laptop to months on supercomputers. I will explain how these simulations help us understand and predict the structure, fate and impact of massive stars. In particular, I will present recent work studying how mass and rotation affect their fate across cosmic times and compare the predicted black-hole mass distribution to the latest gravitational waves detections from the LVK collaboration. I will then introduce the 321D (3 to 1-dimension) loop, a framework to improve 1D stellar evolution models using very detailed 3D hydrodynamic simulations.

第666回
Speaker: Vera Delfavero (Canadian Institute for Theoretical Astrophysics, University of Toronto)
Date: 4/2 Thursday
Time: 16:00 – 17:00
Place: Room 504 seminar room, building 4
Language: English
Title: Simulating Compact Binary Mergers and Gravitational Wave Detections from a Synthetic Universe
Abstract: For the past decade, the LIGO/Virgo/KAGRA (LVK) instruments have detected gravitational waves from merging black holes and neutron stars out to cosmological distances. Population synthesis approaches have simulated the formation channels for such events from isolated binary evolution and various dynamical environments. In this talk I discuss the methods I use to combine different population synthesis codes in order to construct compact binary populations on an observer’s light cone, treating the evolution of star formation and galaxy populations consistently between simulations representing different astrophysical assumptions.