具有模拟黏度的准开普勒Be星盘
Quasi-Keplerian Be-Star Disks with Mimicking Viscosity
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中文总结 AI 辅助
本研究耦合m-CAK线驱动风理论与模拟黏性处方，用Hydwind求解方程，发现特定参数下可得到带m-CAK临界点的准开普勒Be星盘，为VDD旋转处方的影响提供了一维测试。
中文摘要 AI 辅助
经典Be星是快速旋转的B型恒星，拥有由赤道抛射物质形成的气态准开普勒盘。虽然黏性外流盘（VDD）模型能重现诸多观测特性，但辐射线驱动在塑造这些星盘过程中的作用仍不明确。本研究通过将线驱动风的m-CAK理论与由参数γ_vis控制的模拟黏性处方耦合，探究了黏度和辐射加速度对Be星盘流体动力学结构的共同影响。我们使用Hydwind求解了典型B型恒星参数下跨声速Ω慢外流的稳态流体动力学运动方程，分析了速度和密度结构，并推导了在采用的外积分半径r=50R_*处的质量损失率和径向速度。线驱动与黏度的共同作用产生了具有VDD启发式旋转处方的赤道外流的规则m-CAK Ω慢解。对于准开普勒指数（γ_vis≈0.5）和近临界旋转（Ω≈0.96–0.99），模型在r_c≲20–30R_*处产生带有m-CAK型临界点的外流盘；在50R_*处，这些准开普勒解达到76.9–139.2km·s⁻¹的径向速度。在当前一维参数化框架内，m-CAK线力无需施加外边界条件即可得到稳态解。本研究结果为VDD启发式旋转处方如何修改稳态m-CAK Ω慢解的拓扑结构提供了可控的一维测试，该模型是通向未来非 Sobolev 多维辐射流体动力学处理的探索性桥梁，这类处理将重现Be盘的准开普勒旋转和适度外流速度。
英文摘要
Classical Be stars are fast-rotating B-type stars with gaseous quasi-Keplerian disks formed by equatorial ejection of material. While the viscous decretion disk (VDD) model reproduces many observed properties, the role of radiative line driving in shaping these disks remains unclear. We investigated the combined influence of viscosity and radiative acceleration on the hydrodynamic structure of Be star disks by coupling the m-CAK theory of line-driven winds with a mimicking viscous prescription governed by the parameter $γ_{\rm vis}$. We solved the steady-state hydrodynamic equation of motion using \textsc{Hydwind} for typical B-type stellar parameters in transonic $Ω$-slow outflows. We analyzed the velocity and density structures and derived the mass-loss rates and radial velocities at the adopted outer integration radius, $r=50\,R_\ast$. The combined action of line driving and viscosity yields regular m-CAK $Ω$-slow solutions for equatorial outflow with a VDD-inspired rotational prescription. For quasi-Keplerian exponents ($γ_{\rm vis} \simeq 0.5$) and near-critical rotation ($Ω\approx 0.96$--$0.99$), the models produce an outflowing disk with an m-CAK-type critical point at $r_{\rm c} \lesssim 20$--$30\,R_\ast$. At $50\,R_\ast$, these quasi-Keplerian solutions reach radial velocities of $76.9$--$139.2\,\mathrm{km\,s^{-1}}$. Within the present 1D parameterized framework, the m-CAK line force yields stationary solutions without imposing an outer boundary condition. Our results provide a controlled 1D test of how a VDD-inspired rotational prescription modifies the topology of stationary m-CAK $Ω$-slow solutions. The model is an exploratory bridge toward future non-Sobolev multidimensional radiation-hydrodynamic treatments that recover quasi-Keplerian rotation and modest outflow velocities of Be disks.
