arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1503.09106astro-ph.SR
收藏

太阳黑子光球运行半影波的特征

Signatures of running penumbral waves in sunspot photospheres

Johannes Löhner-Böttcher, Nazaret Bello González

摘要:

太阳黑子上方的高动态大气中存在着丰富的磁流体动力学(MHD)波。最近的研究表明,最突出的现象耦合的性质:本影闪光(UF)和运行半影波(RPWs)。从观测的角度来看,我们进行了高度相关的研究RPWs,比较它们的波的特性,并旨在跟踪这些迄今为止只有色球观察到的现象,以证明向上传播的场引导的性质的RPWs光球层。利用干涉二维分光偏振仪(IBIS/DST)对一个孤立的圆形黑子(NOAA 11823)进行了58 μ m分时多波长的分光观测。通过多层强度采样、速度比较、小波功率分析和时间片的扇形研究,反演了太阳黑子波在光球层和色球层的功率分布、特征周期和传播特性。在光球层发现了RPW的特征。这些连续振荡优选地发生在从内部半影边界开始的4- 6 min之间的周期。光球振荡都有一个稍微延迟的,更明确的色球对应物,具有更大的相对速度(这与之前的UF事件有关)。在各层中,RPW的功率分布呈现出随波浪周期的增大而增大的典型环形分布。时间片的分析揭示了RPW在$\approx50\,\rm{km/s}$光球层的视水平速度,在色球层高度降低到$\approx30\,\rm{km/s}$。观测结果强烈支持的情况下,RPWs是向上传播的慢模波引导的磁场线。

英文摘要:

The highly dynamic atmosphere above sunspots exhibits a wealth of magnetohydrodynamic (MHD) waves. Recent studies suggest a coupled nature of the most prominent phenomena: umbral flashes (UFs) and running penumbral waves (RPWs). From an observational point of view, we perform a height-dependent study of RPWs, compare their wave characteristics and aim to track down these so far only chromospherically observed phenomena to photospheric layers to prove the upward propagating field-guided nature of RPWs. We analyze a time series (58\,min) of multi-wavelength observations of an isolated circular sunspot (NOAA11823) taken at high spatial and temporal resolution in spectroscopic mode with the Interferometric BIdimensional Spectro-polarimeter (IBIS/DST). By means of a multi-layer intensity sampling, velocity comparisons, wavelet power analysis and sectorial studies of time-slices, we retrieve the power distribution, characteristic periodicities and propagation characteristics of sunspot waves at photospheric and chromospheric levels. Signatures of RPWs are found at photospheric layers. Those continuous oscillations occur preferably at periods between 4-6\,min starting at the inner penumbral boundary. The photospheric oscillations all have a slightly delayed, more defined chromospheric counterpart with larger relative velocities (which are linked to preceding UF events). In all layers the power of RPWs follows a filamentary fine-structure and shows a typical ring-shaped power distribution increasing in radius for larger wave periods. The analysis of time-slices reveals apparent horizontal velocities for RPWs at photospheric layers of $\approx50\,\rm{km/s}$ which decrease to $\approx30\,\rm{km/s}$ at chromospheric heights. The observations strongly support the scenario of RPWs being upward propagating slow-mode waves guided by the magnetic field lines.

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。

↑