发表机构
Instituto de Astrofísica de Canarias; Universidad de La Laguna（加那利群岛天体物理研究所; 拉古纳大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用瑞典太阳望远镜的H$\alpha$光谱数据，通过小波分析探测到孔隙色球中驻波共振节点的特征，包括相位180°跳变和功率下降，首次为色球共振腔模型提供了直接观测证据。
AI 中文摘要
活动区大气中存在许多振荡现象。色球层由光球层和过渡区处的陡峭温度梯度所界定，磁声波被限制在该区域内，并可在这一共振腔中形成驻波振荡。我们旨在探测驻波共振节点的特征，这些节点预计会在振荡相位中产生突然的跳变以及功率下降。利用瑞典太阳望远镜获取了孔隙中H$\alpha$谱线的光谱时间序列。通过分析谱线两翼多个光谱位置处的强度，推断了多个大气高度处的速度和温度涨落。采用小波分析来表征不同高度处的相位差和功率。速度与温度之间的相位差显示出$\pm90^{\circ}$的值，这与驻波振荡一致。在H$\alpha\pm0.30$ Å强度所探测的高度附近，发现了温度中存在节点层的可靠证据，例如在相同大气层中检测到温度振荡相位的180$^{\circ}$跳变以及显著的功率下降。共振节点的确切高度取决于空间位置和时间。我们通常发现驻波和传播波的混合。这与泄漏共振腔模型一致，其中波在过渡区被部分反射，而部分波能够传播进入日冕。我们首次报道了太阳色球中共振节点的探测和表征。这一结果为色球共振腔模型提供了强有力的观测支持，并为发展新的日震学技术以研究活动区色球结构铺平了道路。
英文摘要
Active region atmospheres host many oscillatory phenomena. The chromosphere is delimited by steep temperature gradients at the photosphere and transition region, where magnetoacoustic waves are trapped and can form standing oscillations within this resonant cavity. We aim to detect the signature of the resonant nodes of standing waves, which are expected to produce sudden jumps in the oscillatory phase and power dips. Spectroscopic temporal series of H$α$ in a pore were acquired with the Swedish Solar Telescope. The velocity and temperature fluctuations at multiple atmospheric heights were inferred from the analysis of the intensity at many spectral positions along the line wings. Wavelet analysis was employed to characterize the phase differences and the power at different heights. The phase shift between velocity and temperature shows a $\pm90^{\circ}$ value, which is consistent with standing oscillations. Robust evidence of the presence of a nodal layer in the temperature at around the height probed by the intensity at H$α\pm0.30$ Å is found, such as the detection of 180$^{\circ}$ jumps in the phase of the temperature oscillations and remarkable power dips at the same atmospheric layer. The exact height of the resonant nodes depends on the spatial location and time. We generally find a mixture of standing and propagating waves. This is consistent with a leaky resonator where waves are partially reflected at the transition region, while some of them are able to propagate into the corona. For the first time, we report the detection and characterization of resonant nodes in the solar chromosphere. This result provides strong observational support for the chromospheric resonant cavity model and paves the way for the development of new seismological techniques to investigate the structure of active region chromospheres.
CommentsAccepted for publication in A&A
