The regulation of angular momentum in star formation: the secret behind planet formation
| Project/Area Number |
17F17802
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| Research Category |
Grant-in-Aid for JSPS Fellows
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| Allocation Type | Single-year Grants |
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| Section | 外国 |
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| Research Field |
Astronomy
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| Research Institution | Osaka University |
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Principal Investigator |
長峯 健太郎 大阪大学, 理学研究科, 教授 (50714086)
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| Co-Investigator(Kenkyū-buntansha) |
MARCHAND PIERRE 大阪大学, 理学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2017-11-10 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2019: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 2018: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2017: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | 理論天文学 / star formation / numerical simulation / MHD / non-ideal MHD effects / astrochemistry / angular momentum / magnetohydrodynamics / 星形成 / 数値シミュレーション / 磁気流体力学 |
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| Outline of Annual Research Achievements |
The regulation of angular momentum is of prime importance during star formation, as it directly impacts the formation of planets, and the possible fragmentation of the protoplanetary disk leading to the creation of binary stars. The magnetic field plays a major role in this process by slowing down the rotation of the gas. The efficiency of this "braking" depends on the coupling between the magnetic field and the gas, which is related to the chemical environment. Three effects impact the coupling, and therefore the braking. They are "non-ideal magnetohydrodynamics (MHD) effects", namely the Ohmic diffusion, the Hall effect and the ambipolar diffusion. The magnetic field can also launch protostellar outflows, that remove mass and angular momentum from the proto-stellar system.
During the second year of his fellowship, Dr. Marchand have performed numerical simulations of star formation using the eulerian code RAMSES, that includes self-gravity and the ambipolar diffusion. He has studied how the magnetic braking was impacted by the ambipolar diffusion in different chemical environments and with different initial conditions. He determined that in every situation, the magnetic braking removes more angular momentum from the disk than the outflows, which is still a debated question. He found that reducing the number of small dust grains leads to a moderately larger disk, but significantly weaker magnetic braking and protostellar outflows. In this situation, he also found an ionic precursor to the protostellar outflow, a phenomenon never reported before.
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| Research Progress Status |
令和元年度が最終年度であるため、記入しない。
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| Strategy for Future Research Activity |
令和元年度が最終年度であるため、記入しない。
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Report
(3 results)
Research Products
(10 results)
