论文标题
强烈磁化的恒星中磁性磁性波数据包动力学动力学
Magneto-gravity wave packet dynamics in strongly magnetised cores of evolved stars
论文作者
论文摘要
据信磁场是在大型主序列恒星的岩心中产生的,这些磁场可能会在进化的后期阶段生存。对红色巨星中的抑郁偶极模式的观察已被吹捧为这些领域的证据,但是现有的磁理论的预测难以适应几个方面,包括需要将波动能量从核心返回到信封中的一小部分,以及受影响模式的持续性重力样性。在这项工作中,我们使用逼真的恒星模型和磁场构型进行了一项哈密顿射线追踪研究,研究了全球几何形状中磁性雷神波的动力学。该技术适用于波长比背景变化尺度短得多的极限。我们对参数空间进行了全面的探索,研究了波频,球形谐波度,波形极化,进入纬度,野外强度,野外半径和进化状态的作用。我们证明,即使在存在强场的情况下,存在轨迹,其中波浪仍然像重力一样,它们能够像纯重力波那样从核心中反射出来。其余的轨迹是波浪获得明显的alfven特征,被困并最终消散的轨迹。在确定单个波数据包的结果(被困与反射)的结果(陷阱与反射)时,发现方向效应,即波形极化和进入纬度。部分能量从核心返回的津贴为磁假设面临的难题提供了解决方案。
Magnetic fields are believed to be generated in the cores of massive main sequence stars, and these may survive on to later stages of evolution. Observations of depressed dipole modes in red giant stars have been touted as evidence for these fields, but the predictions of existing magnetic theories have difficulty accommodating several aspects, including the need to return a fraction of wave energy from the core to the envelope, and the persistent gravity-like character of affected modes. In this work we perform a Hamiltonian ray tracing study investigating the dynamics of magneto-gravity waves in full spherical geometry, using realistic stellar models and magnetic field configurations. This technique applies in the limit where wavelengths are much shorter than scales of background variation. We conduct a comprehensive exploration of parameter space, examining the roles of wave frequency, spherical harmonic degree, wavevector polarisation, incoming latitude, field strength, field radius, and evolutionary state. We demonstrate that even in the presence of a strong field, there exist trajectories where waves remain predominantly gravity-like in character, and these are able to undergo reflection out of the core much like pure gravity waves. The remaining trajectories are ones where waves acquire significant Alfven character, becoming trapped and eventually dissipated. Orientation effects, i.e. wavevector polarisation and incoming latitude, are found to be crucial factors in determining the outcome (trapped versus reflected) of individual wave packets. The allowance for partial energy return from the core offers a solution to the conundrum faced by the magnetic hypothesis.