Three-dimensional simulations of near-surface convection in main-sequence stars II. Properties of granulation and spectral lines
Three-dimensional simulations of near-surface convection in main-sequence stars II. Properties of granulation and spectral lines
复制标题
主序星近地表对流的三维模拟II 粒化和谱线特性
DOI：
10.1051/0004-6361/201321345
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发表时间：
2013
影响因子：
6.5
通讯作者：
Schüssler
中科院分区：
文献类型：
--
作者：
Cameron;Reiners;Schüssler
冷主序星的大气层是由对流包层的对流流构成的，对流包层穿透光学薄层，导致恒星大气层的结构类似于太阳的颗粒化。的流动有相当大的影响的三维结构的温度和压力，并影响的轮廓谱线形成的光球aimsFor的一套6个3D辐射（M）HD模拟的冷主序星在本系列的第一篇论文中描述的，我们分析了近地表层。我们的目的是描述不同的恒星的颗粒的性质，并在量化的热力学结构和流动的3D对流atmos.MethodsWe检测和跟踪颗粒的亮度图像模拟分析其统计特性，以及它们的演变和寿命的谱线的影响。我们计算了空间分辨谱线轮廓线合成代码SPINOR。为了使比较恒星观测，我们实施了一个数值的光盘集成，其中包括（差分）rotation.ResultsAlthough恒星参数变化相当大沿着模型序列，颗粒的属性是非常相似的。大气层的三维结构对谱线的影响可以用圆盘积分谱来测量。对流引起的线的不对称性调制恒星rotation.ConclusionsThe 3D结构的冷恒星大气对流流的形状时，必须考虑到光球线，以确定恒星参数。
ContextThe atmospheres of cool main-sequence stars are structured by convective flows from the convective envelope that penetrate the optically thin layers and lead to structuring of the stellar atmospheres analogous to solar granulation. The flows have considerable influence on the 3D structure of temperature and pressure and affect the profiles of spectral lines formed in the photosphere.AimsFor the set of six 3D radiative (M)HD simulations of cool main-sequence stars described in the first paper of this series, we analyse the near-surface layers. We aim at describing the properties of granulation of different stars and at quantifying the effects on spectral lines of the thermodynamic structure and flows of 3D convective atmospheres.MethodsWe detected and tracked granules in brightness images from the simulations to analyse their statistical properties, as well as their evolution and lifetime. We calculated spatially resolved spectral line profiles using the line synthesis code SPINOR. To enable a comparison to stellar observations, we implemented a numerical disc-integration, which includes (differential) rotation.ResultsAlthough the stellar parameters change considerably along the model sequence, the properties of the granules are very similar. The impact of the 3D structure of the atmospheres on line profiles is measurable in disc-integrated spectra. Line asymmetries caused by convection are modulated by stellar rotation.ConclusionsThe 3D structure of cool stellar atmospheres as shaped by convective flows has to be taken into account when using photospheric lines to determine stellar parameters.