Fragmentation of Dense Rotation-Dominated Structures Fed by Collapsing Gravomagneto-Sheetlets and Origin of Misaligned 100 au-Scale Binaries and Multiple Systems
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2024
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| author | Tu, Yisheng Li, Zhi-Yun Zhu, Zhaohuan Hsu, Chun-Yen |
| author_facet | Tu, Yisheng Li, Zhi-Yun Zhu, Zhaohuan Hsu, Chun-Yen |
| contents | The majority of stars are in binary/multiple systems. How such systems form in turbulent, magnetized cores of molecular clouds in the presence of non-ideal MHD effects remains relatively under-explored. Through ATHENA++-based non-ideal MHD AMR simulations with ambipolar diffusion, we show that the collapsing protostellar envelope is dominated by dense gravo-magneto-sheetlets, a turbulence-warped version of the classic pseudodisk produced by anisotropic magnetic resistance to the gravitational collapse, in agreement with previous simulations of turbulent, magnetized single-star formation. The sheetlets feed mass, magnetic fields, and angular momentum to a Dense ROtation-Dominated (DROD) structure, which fragments into binary/multiple systems. This DROD fragmentation scenario is a more dynamic variant of the traditional disk fragmentation scenario for binary/multiple formation, with dense spiral filaments created by inhomogeneous feeding from the highly structured larger-scale sheetlets rather than the need for angular momentum transport, which is dominated by magnetic braking. Provided that the local material is sufficiently demagnetized, with a plasma-$β$ of 10 or more, collisions between the dense spiraling filaments play a key role in facilitating gravitational collapse and stellar companion formation by pushing the local magnetic Toomre parameter $Q_\mathrm{m}$ below unity. This mechanism can naturally produce {\it in situ} misaligned systems on the 100-au scale, often detected with high-resolution Atacama Large Millimeter Array (ALMA) observations. Our simulations also highlight the importance of non-ideal MHD effects, which affect whether fragmentation occurs and, if so, the masses and orbital parameters of the stellar companions formed. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2403_07777 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Fragmentation of Dense Rotation-Dominated Structures Fed by Collapsing Gravomagneto-Sheetlets and Origin of Misaligned 100 au-Scale Binaries and Multiple Systems Tu, Yisheng Li, Zhi-Yun Zhu, Zhaohuan Hsu, Chun-Yen Solar and Stellar Astrophysics Astrophysics of Galaxies The majority of stars are in binary/multiple systems. How such systems form in turbulent, magnetized cores of molecular clouds in the presence of non-ideal MHD effects remains relatively under-explored. Through ATHENA++-based non-ideal MHD AMR simulations with ambipolar diffusion, we show that the collapsing protostellar envelope is dominated by dense gravo-magneto-sheetlets, a turbulence-warped version of the classic pseudodisk produced by anisotropic magnetic resistance to the gravitational collapse, in agreement with previous simulations of turbulent, magnetized single-star formation. The sheetlets feed mass, magnetic fields, and angular momentum to a Dense ROtation-Dominated (DROD) structure, which fragments into binary/multiple systems. This DROD fragmentation scenario is a more dynamic variant of the traditional disk fragmentation scenario for binary/multiple formation, with dense spiral filaments created by inhomogeneous feeding from the highly structured larger-scale sheetlets rather than the need for angular momentum transport, which is dominated by magnetic braking. Provided that the local material is sufficiently demagnetized, with a plasma-$β$ of 10 or more, collisions between the dense spiraling filaments play a key role in facilitating gravitational collapse and stellar companion formation by pushing the local magnetic Toomre parameter $Q_\mathrm{m}$ below unity. This mechanism can naturally produce {\it in situ} misaligned systems on the 100-au scale, often detected with high-resolution Atacama Large Millimeter Array (ALMA) observations. Our simulations also highlight the importance of non-ideal MHD effects, which affect whether fragmentation occurs and, if so, the masses and orbital parameters of the stellar companions formed. |
| title | Fragmentation of Dense Rotation-Dominated Structures Fed by Collapsing Gravomagneto-Sheetlets and Origin of Misaligned 100 au-Scale Binaries and Multiple Systems |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2403.07777 |