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A new type of accretion flow in high-mass X-ray binaries with circumstellar disks

Research Project

Project/Area Number 21K03619
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 16010:Astronomy-related
Research InstitutionHokkai-Gakuen University

Principal Investigator

Okazaki Atsuo  北海学園大学, 開発研究所, 特別研究員 (00185414)

Project Period (FY) 2021-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2023: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2022: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2021: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywords恒星風 / 降着円盤 / X線連星 / 大質量連星系 / Be星 / 星周円盤 / 潮汐相互作用 / X線 / X線連星系 / 降着流
Outline of Research at the Start

大質量X線連星系(大質量星と中性子星やブラックホールからなる連星系)の約半数で星周円盤と呼ばれるガス円盤が大質量星のまわりに形成される。一般に、星周円盤は連星系の軌道面に対して傾いているが、申請者は最近、3次元シミュレーションにより、そのような連星系で、降着流の角運動量ベクトルが軌道周期で大きく歳差運動する現象を見いだした。本研究では、星周円盤と軌道面の角度を様々に変えてシミュレーションを行い、この新しいタイプの降着流が生じる仕組みを明らかにする。また、解析的なアプローチも用いて、傾斜した星周円盤を持つ系における降着流の一般論を構築する。

Outline of Final Research Achievements

The Be/X-ray binary systems, the largest subgroup of high-mass X-ray binaries, consist of a neutron star and a Be star, which is a massive star with a circumstellar disk. In this study, we performed simulations of the accretion flow that occurs when the circumstellar disk is tilted relative to the binary orbital plane. We discovered that when the Be star's circumstellar disk is significantly tilted around the minor axis of the binary orbit, the two accretion flows occurring before and after periastron collide, causing the direction of the accretion flow to exhibit precession synchronized with the orbital period. Additionally, we examined the impact of the Be star's stellar wind on the accretion flow when the circumstellar disk is inclined relative to the orbital plane. Our findings suggest that in many Be/X-ray binary systems, the accretion flow is likely to be stripped away by the stellar wind during quiescent phases.

Academic Significance and Societal Importance of the Research Achievements

本研究の学術的意義は、X線連星系の主要グループの1つであるBe/X線連星系において、星周円盤が軌道面に対して傾斜している場合に生じる複雑な相互作用を明らかにした点にある。特に、星周円盤が軌道面に対して傾斜している場合に生じる降着流の挙動を3次元シミュレーションにより調べ、傾斜した円盤が降着流の早い歳差運動を引き起こすことを見いだした。この発見は降着流の物理に対する新しい理解をもたらすものである。また、恒星風が降着流に与える影響を定量的に評価し、多くのBe/X線連星系で恒星風が降着流を剥ぎ取る可能性が高いことを示した。これにより、降着流と恒星風の相互作用について新たな知見を提供した。

Report

(4 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Research-status Report
  • 2021 Research-status Report
  • Research Products

    (6 results)

All 2024 2023 2022 2021

All Journal Article (1 results) (of which Peer Reviewed: 1 results) Presentation (5 results) (of which Int'l Joint Research: 3 results)

  • [Journal Article] Novel application to estimate the mass-loss and the dust-formation rates in O-type gamma-ray binaries using near-infrared photometry2023

    • Author(s)
      Moritani Yuki、Kawachi Akiko、Okazaki Atsuo T、Chimasu Sho、Yoshida Hiromi
    • Journal Title

      Publications of the Astronomical Society of Japan

      Volume: 75 Issue: 3 Pages: 607-618

    • DOI

      10.1093/pasj/psad022

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Presentation] Inhibition of Accretion by the Stellar Wind in Misaligned Be/X-ray Binaries2024

    • Author(s)
      岡崎敦男
    • Organizer
      日本天文学会
    • Related Report
      2023 Annual Research Report
  • [Presentation] Be stars and disks: their interaction with compact objects2023

    • Author(s)
      岡崎敦男
    • Organizer
      Variable Galactic Gamma-Ray Sources VI
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Inhibition of accretion by the stellar wind in misaligned Be/X-ray binaries2023

    • Author(s)
      岡崎敦男
    • Organizer
      3,2,1: Massive Triples, Binaries and Mergers 2023
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Collision between the stellar wind and the accretion disk in misaligned Be/X-ray binaries2022

    • Author(s)
      岡崎敦男
    • Organizer
      日本天文学会
    • Related Report
      2022 Research-status Report
  • [Presentation] Periodic variations in the accretion disk orientation in misaligned Be/X-ray binaries2021

    • Author(s)
      Atsuo Okazaki
    • Organizer
      Be/X-ray Binaries Workshop 2021
    • Related Report
      2021 Research-status Report
    • Int'l Joint Research

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Published: 2021-04-28   Modified: 2025-01-30  

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