Structure Formation of Planetary Systems by Chain Accretion

• Project/Area Number: 16K05304
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Kokubo Eiichiro 国立天文台, 理論研究部, 教授 (90332163)
• Research Collaborator: Lin Douglas
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2018: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000); Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2016: ¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
• Keywords: 惑星系形成 / 太陽系 / 惑星集積 / 多体シミュレーション / 理論天文学 / 惑星起源・進化

Outline of Final Research Achievements

The goal of this project is to investigate the elementary process of structure formation of planetary systems with multiple planets along with a working hypothesis "chain accretion scenario" and understand the origin of the orbital architecture of the solar and exoplanetary systems.

We have developed a fast N-body simulation system "planet formation simulator" that consists of an N-body simulation code for planetesimal accretion and a general-purpose graphic processing unit (GPU) that accelerates gravity calculation. The simulation code takes into account the realistic evolution of disk gas and accretionary condition of planetesimals. Using it we are now investigating the effect of the first gas giant on the formation of the second one, namely, the evolution of outer planetesimals, which is the important elementary process of the chain accretion scenario.

Academic Significance and Societal Importance of the Research Achievements

太陽系も含めて、銀河系に存在する多くの惑星系は複数惑星系である。このような惑星系の軌道構造の起源を理解することは惑星系形成論の重要な課題である。惑星系形成の作業仮説である「連鎖集積シナリオ」では最初に形成された巨大惑星がその後の形成過程を支配すると考える。その素過程をシミュレーションによって調べている。この過程を理解することで太陽系の起源に迫ることができる。また、シミュレーションのために開発した GPU を用いたシミュレーションコードは公開予定である。これは今後のこの分野の研究に貢献できると考えている。

Research Products

• [Presentation] Formation of Terrestrial Planets by Giant Impacts (2019)
  • Author(s): 小久保英一郎
  • Organizer: Solar System | Exoplanet Science Synergies in the Horizon 2061
  • Int'l Joint Research / Invited
• [Presentation] Formation of Terrestrial Planets (2019)
  • Author(s): 小久保英一郎
  • Organizer: LIFE3E’2019: SEARCH FOR LIFE, FROM EARLY EARTH TO EXOPLANETS
  • Int'l Joint Research / Invited
• [Presentation] The Standard Scenario of Solar System Formation and its Problems (2018)
  • Author(s): 小久保英一郎
  • Organizer: Asia Oceania Geosciences Society 15th Annual Meeting
  • Int'l Joint Research / Invited
• [Presentation] Formation of Terrestial Planets (2018)
  • Author(s): 小久保英一郎
  • Organizer: IAU Symposium 345: Origins: From the Protosun to the First Steps of Life
  • Int'l Joint Research / Invited
• [Presentation] Formation of Terrestrial Planets (2017)
  • Author(s): Eiichiro Kokubo
  • Organizer: Formation of the Solar System and the Origin of Life
  • Place of Presentation: University of Leiden (The Netherlands)
  • Year and Date: 2017-02-20
  • Int'l Joint Research / Invited
• [Presentation] Orbital Architecture of Planetary Systems Formed by Giant Impacts (2017)
  • Author(s): Eiichiro Kokubo
  • Organizer: Accretion and Early Differentiation of the Earth and Terrestrial Planets
  • Int'l Joint Research
• [Presentation] Orbital Architecture of Close-in Planetary Systems Formed by Giant Impacts (2017)
  • Author(s): Eiichiro Kokubo
  • Organizer: Exoplanets and Planet Formation
  • Int'l Joint Research / Invited
• [Presentation] 巨大衝突によって形成される惑星系の構造 (2016)
  • Author(s): 小久保英一郎
  • Organizer: 日本惑星科学会
  • Place of Presentation: ノートルダム清心女子大学（岡山県，岡山市）
  • Year and Date: 2016-09-12