arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0902.2299astro-ph.SR
收藏

根据HINODE观测太阳表面上的中尺度动力学

Mesoscale dynamics on the Sun's surface from HINODE observations

T. Roudier, M. Rieutord, D. Brito, F. Rincon, J. M. Malherbe, N. Meunier, T. Berger, Z. Frank

摘要:

目的:太阳表面速度尺度的相互作用,从颗粒到超颗粒,仍然没有被理解,它们与磁场的相互作用也是如此。因此,我们的目标是更好地描述中尺度范围内的动力学,它位于上述两个尺度之间。方法:我们分析了48小时的高分辨率时间序列的安静的太阳光球在磁盘中心获得的太阳光学望远镜船上日之出。观测的视场为100 \arcsec $\times$ 100 \arcsec,通常包含四个超颗粒。我们详细监测颗粒的运动和演化以及径向磁场的运动和演化。结果如下:这种分析使我们能够更好地表征从颗粒的重复破碎发出的破碎颗粒树,特别是它们的寿命统计。使用浮动软木平流测量速度场,我们展示了他们的至关重要的作用,在平流的磁场和网络的建立。最后,由于时间序列的持续时间长,我们估计由水平运动引起的湍流扩散系数近似为$430 \mathrm{km}^2 \mathrm{s}^{-1}$。结论:这些结果表明,长寿命的家庭有助于形成的磁网络,并建议超颗粒可能是一个新兴的长度规模建立小磁性元素平流和集中的TFG流。我们的估计与这种水平运动的磁扩散可能会提供一个有用的输入平均场发电机模型。

英文摘要:

Aims: The interactions of velocity scales on the Sun's surface, from granulation to supergranulation are still not understood, nor are their interaction with magnetic fields. We thus aim at giving a better description of dynamics in the mesoscale range which lies between the two scales mentioned above. Method: We analyse a 48h high-resolution time sequence of the quiet Sun photosphere at the disk center obtained with the Solar Optical Telescope onboard Hinode. The observations, which have a field of view of 100 \arcsec$\times$ 100 \arcsec, typically contain four supergranules. We monitor in detail the motion and evolution of granules as well as those of the radial magnetic field. Results: This analysis allows us to better characterize Trees of Fragmenting Granules issued from repeated fragmentation of granules, especially their lifetime statistics. Using floating corks advected by measured velocity fields, we show their crucial role in the advection of the magnetic field and in the build up of the network. Finally, thanks to the long duration of the time series, we estimate that the turbulent diffusion coefficient induced by horizontal motion is approximately $430 \mathrm{km}^2 \mathrm{s}^{-1}$. Conclusions: These results demonstrate that the long living families contribute to the formation of the magnetic network and suggest that supergranulation could be an emergent length scale building up as small magnetic elements are advected and concentrated by TFG flows. Our estimate for the magnetic diffusion associated with this horizontal motion might provide a useful input for mean-field dynamo models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑