利用全局数值模拟,研究组确定了由磁发电机产生的由层流到湍流的亚临界转变。他们的结果具有理论提出的taylor - spruit发电机机制的许多性质,它强烈地增强了角动量在辐射区的传输。发电机产生的深环形磁场被恒星外层所屏蔽。这种机制可以在辐射恒星内部产生强磁场,而在它们的表面没有可观测的磁场。
据了解,恒星的演化受到其内部旋转动力学通过输运和混合机制的影响,但人们对这一机制了解甚少。磁场可以在角动量和化学元素的传输中发挥作用,但辐射恒星层中磁性的起源尚不清楚。
附:英文原文
Title: Spin-down by dynamo action in simulated radiative stellar layers
Author: Ludovic Petitdemange, Florence Marcotte, Christophe Gissinger
Issue&Volume: 2023-01-20
Abstract: The evolution of a star is influenced by its internal rotation dynamics through transport and mixing mechanisms, which are poorly understood. Magnetic fields can play a role in transporting angular momentum and chemical elements, but the origin of magnetism in radiative stellar layers is unclear. Using global numerical simulations, we identify a subcritical transition from laminar flow to turbulence caused by the generation of a magnetic dynamo. Our results have many properties of the theoretically proposed Tayler-Spruit dynamo mechanism, which strongly enhances transport of angular momentum in radiative zones. The dynamo generates deep toroidal fields that are screened by the stellar outer layers. This mechanism could produce strong magnetic fields inside radiative stars without an observable field on their surface.
DOI: abk2169
Source: https://www.science.org/doi/10.1126/science.abk2169