吸积 T Tauri 星的磁制动 II：跨越自旋向上和自旋向下机制的扭矩公式,The Astrophysical Journal

当前位置： X-MOL 学术 › Astrophys. J. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

吸积 T Tauri 星的磁制动 II：跨越自旋向上和自旋向下机制的扭矩公式
The Astrophysical Journal ( IF 4.8 ) Pub Date : 2022-04-13 , DOI: 10.3847/1538-4357/ac59b2
Lewis G. Ireland ₁ , Sean P. Matt ₁ , Claudio Zanni ₂

Affiliation

经典的 T Tauri 恒星与其周围的吸积盘之间的磁相互作用被认为会影响其旋转演化。我们使用 2.5D 磁流体动力学、星盘相互作用的轴对称模拟（通过 PLUTO 代码计算）来计算作用在这些恒星上的净扭矩。我们将净扭矩分为三个贡献：吸积（自旋向上）、恒星风（自旋向下）和磁层抛射 (ME)（自旋向上或向下）。在论文 I 中，我们探索了恒星磁层在旋转速度比恒星快的位置截断内盘的相互作用机制，从而导致吸积和 ME 产生强大的净旋转贡献（“稳定吸积”机制）。在本文中，我们研究了截断半径接近甚至超过共转的相互作用机制，圆盘材料有可能获得角动量并被离心屏障（“螺旋桨”状态）周期性地弹出。这减少了吸积力矩，可以改变 ME 力矩的符号，并且可以导致净恒星自旋减速配置。这些结果表明，即使对于同转半径内的截断半径，也可能有一个净自旋向下的恒星扭矩（R _t≳0.7 _R _合）。我们拟合了截断半径的半解析函数，以及与星盘相互作用相关的扭矩（即吸积和 ME 扭矩的总和）和恒星风，允许预测涵盖两者的参数范围的净恒星扭矩净自旋向上和自旋向下配置，以及通过一维恒星演化代码研究旋转演化的可能性。

"点击查看英文标题和摘要"

Magnetic Braking of Accreting T Tauri Stars II: Torque Formulation Spanning Spin-up and Spin-down Regimes

The magnetic interaction between a classical T Tauri star and its surrounding accretion disk is thought to influence its rotational evolution. We use 2.5D magnetohydrodynamic, axisymmetric simulations of star-disk interaction, computed via the PLUTO code, to calculate the net torque acting on these stars. We divide the net torque into three contributions: accretion (spin-up), stellar winds (spin-down), and magnetospheric ejections (MEs) (spin-up or down). In Paper I, we explored interaction regimes in which the stellar magnetosphere truncates the inner disk at a location spinning faster than the star, resulting in a strong net spin-up contribution from accretion and MEs (“steady accretion” regime). In this paper, we investigate interaction regimes in which the truncation radius gets closer to and even exceeds corotation, where it is possible for the disk material to gain angular momentum and be periodically ejected by the centrifugal barrier (“propeller” regime). This reduces the accretion torque, can change the sign of the ME torque, and can result in a net stellar spin-down configuration. These results suggest it is possible to have a net spin-down stellar torque even for truncation radii within the corotation radius (R _t ≳ 0.7R _co). We fit semi-analytic functions for the truncation radius, and the torque associated with star-disk interaction (i.e., the sum of accretion and ME torques) and stellar wind, allowing for the prediction of the net stellar torque for a parameter regime covering both net spin-up and spin-down configurations, as well as the possibility of investigating rotational evolution via 1D stellar evolution codes.

更新日期：2022-04-13

点击分享查看原文

点击收藏

公开下载

阅读更多本刊新发论文