论文标题
对沿红色巨型分支内部旋转的呼吸震敏感
Asteroseismic sensitivity to internal rotation along the red-giant branch
论文作者
论文摘要
目前尚不清楚恒星内饰中角动量的运输。 Asterosemology可以为我们提供恒星内部旋转的估计,从而提高我们对角动量运输的理解。我们可以测量红色巨星中的核心旋转速率,我们可以使用偶极子($ L = 1 $)模式的测量表面旋转速率放置上限。在这里,我们旨在确定不同球形程度对表面旋转的模式的理论灵敏度。此外,我们旨在确定可以在中间半径上增加灵敏度的模式。我们使用的是从红色巨型分支的底部到亮度凸起的红色巨型模型中的红色巨型模型中的内部恒星旋转轮廓来探测内部恒星旋转曲线。我们使用了乘法最佳定位平均值(MOLA)的反演方法来评估如何从不同模式集和不同的合成旋转曲线中恢复内部和表面旋转速率。我们确认,偶极子混合模式足以设定红色巨人平均核心旋转率的约束。然而,仅偶极混合模式估计的表面旋转速率被核心旋转污染。我们表明,对表面旋转的敏感性从红色巨型分支的底部降低,直到由于浮力在浮力频率中的故障而达到0.6-0.8 $ l_ \ text {bump} $的最小值。此后,存在狭窄的表面灵敏度在凸起的亮度下方。四极杆和章鱼模式在恒星的外部具有更大的灵敏度。如果观察到,四极和章鱼模式使我们能够区分对流区域的差分和固体旋转。为了获得中间半径上旋转速率的准确估计,需要球形振荡模式为$ l \ \ 10 $。
Transport of angular momentum in stellar interiors is currently not well understood. Asteroseismology can provide us with estimates of internal rotation of stars and thereby advances our understanding of angular momentum transport. We can measure core-rotation rates in red-giant stars and we can place upper bounds on surface-rotation rates using measurements of dipole ($l=1$) modes. Here, we aim to determine the theoretical sensitivity of modes of different spherical degree towards the surface rotation. Additionally, we aim to identify modes that can potentially add sensitivity at intermediate radii. We used asteroseismic rotational inversions to probe the internal stellar rotation profiles in red-giant models from the base of the red-giant branch up to the luminosity bump. We used the inversion method of multiplicative optimally localised averages (MOLA) to assess how well internal and surface rotation rates can be recovered from different mode sets and different synthetic rotation profiles. We confirm that dipole mixed modes are sufficient to set constraints on the average core-rotation rates in red giants. However, surface-rotation rates estimated with only dipole mixed modes are contaminated by the core rotation. We show that the sensitivity to the surface rotation decreases from the base of the red-giant branch until it reaches a minimum at 0.6-0.8$L_\text{bump}$ due to a glitch in the buoyancy frequency. Thereafter a narrow range of increased surface sensitivity just below the bump luminosity exists. Quadrupole and octopole modes have more sensitivity in the outer parts of the star. If observed, quadrupole and octopole modes enable us to distinguish between differential and solid body rotation in the convection zone. To obtain accurate estimates of rotation rates at intermediate radii, acoustic oscillation modes with a spherical degree of $l\approx10$ are needed.