Dependence of Hall coefficient on grain size and cosmic ray rate and implication for circumstellar disc formation

Shunta Koga, Yusuke Tsukamoto, Satoshi Okuzumi, Masahiro Machida

研究成果: ジャーナルへの寄稿記事

抄録

The Hall effect plays a significant role in star formation, because it induces rotation in the infalling envelope, which in turn affects the formation and evolution of the circumstellar disc. The importance of the Hall effect varies with the Hall coefficient, and this coefficient is determined by the fractional abundances of charged species. These abundance values are primarily based on the size and quantity of dust grains as well as the cosmic ray intensity, which, respectively, absorb and create charged species. Thus, the Hall coefficient varies with both the properties of dust grains and the cosmic ray rate (or ionization source). In this study, we explore the dependence of the Hall coefficient on the grain size and cosmic ray ionization rate using a simplified chemical network model. Following this, using an analytic model, we estimate the typical size of a circumstellar disc induced solely by the Hall effect. The results show that the disc grows during the main accretion phase to a size of ∼3-100 au, with the actual size depending on the parameters. These findings suggest that the Hall effect greatly affects circumstellar disc formation, especially in the case that the dust grains have a typical size of ∼0.025 − 0.075 μm.

元の言語英語
ページ(範囲)2119-2136
ページ数18
ジャーナルMonthly Notices of the Royal Astronomical Society
484
発行部数2
DOI
出版物ステータス出版済み - 1 1 2019

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cosmic ray
Hall effect
cosmic rays
rays
grain size
dust
ionization
accretion
rate
star formation
effect
envelopes
coefficients
estimates

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

これを引用

Dependence of Hall coefficient on grain size and cosmic ray rate and implication for circumstellar disc formation. / Koga, Shunta; Tsukamoto, Yusuke; Okuzumi, Satoshi; Machida, Masahiro.

:: Monthly Notices of the Royal Astronomical Society, 巻 484, 番号 2, 01.01.2019, p. 2119-2136.

研究成果: ジャーナルへの寄稿記事

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abstract = "The Hall effect plays a significant role in star formation, because it induces rotation in the infalling envelope, which in turn affects the formation and evolution of the circumstellar disc. The importance of the Hall effect varies with the Hall coefficient, and this coefficient is determined by the fractional abundances of charged species. These abundance values are primarily based on the size and quantity of dust grains as well as the cosmic ray intensity, which, respectively, absorb and create charged species. Thus, the Hall coefficient varies with both the properties of dust grains and the cosmic ray rate (or ionization source). In this study, we explore the dependence of the Hall coefficient on the grain size and cosmic ray ionization rate using a simplified chemical network model. Following this, using an analytic model, we estimate the typical size of a circumstellar disc induced solely by the Hall effect. The results show that the disc grows during the main accretion phase to a size of ∼3-100 au, with the actual size depending on the parameters. These findings suggest that the Hall effect greatly affects circumstellar disc formation, especially in the case that the dust grains have a typical size of ∼0.025 − 0.075 μm.",
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