A new approach for stability analysis of magnetized stars

Research Project

Project/Area Number	18K03606
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
Research Institution	Tohoku University
Principal Investigator	Yoshida Shijun 東北大学, 理学研究科, 助教 (30386635)
Project Period (FY)	2018-04-01 – 2021-03-31
Project Status	Completed (Fiscal Year 2020)
Budget Amount *help	¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000) Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2018: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Keywords	理論宇宙物理 / 宇宙物理(理論) / 中性子星 / 安定性 / 磁場
Outline of Final Research Achievements	The formulation for analyzing stability of magnetized stars are obtained. The formulation is based on a variational principle, which can be applied to a numerical approach with the finite element method. The construction of the numerical code for examining stabilities of magnetized stars is developed, although it is not finished yet. Equilibrium states of magnetized stars, which are required for examining their stability, are studied. Main results are summarized as follows: (i) Stars containing magnetic fields whose toroidal components are much larger than the poloidal ones in general relativity are obtained. (ii) Considering general magnetic field structures, we obtain magnetized stars within the framework of general relativity. (iii) Magnetized stars surrounded by plasma are investigated. (iv) Effects of the surface current on the stellar surface on the structure of the star are studied.
Academic Significance and Societal Importance of the Research Achievements	コンパクト天体の磁場は、高エネルギー天体現象の最も重要な要素の一つであり、磁場無しでは多くの現象を説明できない。その一方で、コンパクト天体に存在する磁場が基本的には不安定であることが指摘されている。これが事実なら非常に深刻な問題であり、磁場を伴う星の安定性は、天体物理においで、重要な問題となる。しかし、今のところ、磁場星の安定性を解析する正確で有効な方法は知られていない。本研究課題では、磁場星の安定性を解析する数値解析方法を進展させたという意味で意義がある。最終的な成果は得られていないが、今後、研究を進めることで、最終的な成果が得られると期待される。