The Origin of Stellar Rotation Unraveled by the Synergy of Stellar Evolution and Star Formation Simulations

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K20377
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0204:Astronomy, earth and planetary science, and related fields
• Research Institution: National Astronomical Observatory of Japan (2023); Tohoku University (2022)
• Principal Investigator: Takahashi Koh 国立天文台, 科学研究部, 助教 (20963987)
• Project Period (FY): 2022-08-31 – 2024-03-31
• Keywords: 恒星進化 / 星形成 / 角運動量輸送 / 磁気圏 / 境界層

Outline of Final Research Achievements

Although angular momentum is a crucial factor in stellar evolution, the process in which angular momentum is introduced into the central star, which provides the initial conditions, remains unclear. Therefore, the aim of this study is to elucidate the mechanism by which angular momentum is introduced. During the growth phase of protostars, a process of angular momentum extraction, which counteracts angular momentum insertion due to gas accretion, is indispensable. I developed a model that considers magnetic angular momentum extraction and elucidated the temporal evolution of angular momentum during the accretion phase of protostellar evolution. Additionally, models have been developed to resolve the three-region structure of protostar-boundary layer-disk, allowing for the evaluation of the efficiency and evolution of angular momentum extraction due to viscosity.

Free Research Field

恒星物理学

Academic Significance and Societal Importance of the Research Achievements

恒星という宇宙の構成要素を理解する上でそれがどうできたのかを理解することには大きな意義がある。本研究では恒星を特徴づける量のなかから角運動量に注目し、星がどのような過程で角運動量を獲得したのかの解明に取り組んだ。今回開発した理論手法は今後拡張することが可能で、その他の特徴量である磁場強度や、連星・多重星形成過程を調査するのに用いることを企図している。星形成、とくに大質量星の形成過程は観測的な検証の進んでいない分野であり、理解を進めるうえで理論研究の果たす役割は大きい。また今後 ngVLA をはじめとした新しい観測手段が出現することが予測でき、将来に備え理論モデルの整備を行う点でも意義深い。