发表机构
ETH Zurich, Institute for Particle Physics and Astrophysics; Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte d’Azur; Université Grenoble Alpes, CNRS, IPAG; Aix Marseille Univ, CNRS, LAM, Laboratoire d’Astrophysique de Marseille; LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité; Max-Planck-Institut für Astronomie; INAF – Osservatorio Astronomico di Padova（苏黎世联邦理工学院，粒子物理与天体物理研究所; 拉格朗日实验室，尼斯索菲亚-安蒂波利斯大学，法国国家科学研究中心，蔚蓝海岸天文台; 格勒诺布尔阿尔卑斯大学，法国国家科学研究中心，IPAG; 艾克斯马赛大学，法国国家科学研究中心，LAM，马赛天体物理实验室; LESIA，巴黎天文台，PSL研究大学，法国国家科学研究中心，索邦大学，UPMC巴黎第六大学，巴黎第七大学，索邦巴黎城; 马克斯·普朗克天文学研究所; 意大利国家天体物理研究所，帕多瓦天文台）
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SPHERE/ZIMPOL高分辨率观测，分析共生Mira双星R Aqr中尘埃与Hα气体的动力学，揭示双星附近的相互作用、尘埃掩食效应及喷流加速机制。
AI 中文摘要
R Aqr是一个已分辨的共生Mira双星系统，是研究复杂流体动力学过程（包括尘埃驱动的质量损失、质量转移、吸积、喷流外流以及强不对称结构的形成）的典型目标。我们基于SPHERE/ZIMPOL的成像数据，分辨率约为25毫角秒（5天文单位），研究了R Aqr中心电离气体的Hα发射和散射尘埃的偏振。我们获取了四个历元的数据，包括2021年前后的尘埃掩食，以追踪结构变化。中心的Hα气体追踪了热伴星的轨道运动。散射尘埃的偏振显示了双星附近（<60天文单位）的相互作用效应，包括轨道平面内的扁平分布、共转尘埃，以及在尘埃掩食期间散射信号的减弱。在大于60天文单位的区域，偏振显示了一个稳定的外流，包含约十几个尘埃云，其中一些具有类似彗星的核和尾特征。尘埃速度约为20公里/秒，比ALMA测量的CO气体速度更快。几个显著的Hα云也显示出散射偏振，因为它们只是来自Mira星风的部分电离尘埃云。我们还发现了小的、移动更快的瞬态Hα云，表明存在外流不稳定性和激波。在尘埃掩食期间观测到的Hα角位移，可以通过热伴星的强烈光照变化来解释。在更大分离距离处，Hα云移动得更快（>100公里/秒），与之前的研究一致。这种加速可能是光电离和激波导致气体加热的结果，产生的过压形成了两个众所周知的沿极向膨胀的喷流状特征。所呈现的R Aqr数据对于阐明AGB双星中发生的复杂流体动力学非常有用。
英文摘要
R Aqr is a resolved symbiotic Mira binary and a prototype target for the study of complex hydrodynamic processes including dust-driven mass loss, mass transfer, accretion, and jet outflows and the formation of strongly asymmetric structures. We investigate for R Aqr the central Halpha emission from the ionized gas and the polarization from scattering dust based on SPHERE/ZIMPOL maps with a resolution of about 25 mas (5 AU). Data for four epochs were taken, including the dust eclipse around 2021, to follow structural changes. The central Halpha gas traces the orbital motion of the hot component. The polarization from scattering dust shows interaction effects near the binary (<60 AU), including a flattened distribution in the orbital plane, corotating dust, and a reduction of the scattering signal during the dust eclipse. The polarization shows at >60 AU a steady outflow with about a dozen dust clouds, a few of which have a comet-like core and tail features. The dust velocity is about 20 km/s, and this is faster than for the CO gas measured with ALMA. Several prominent Halpha clouds also show scattering polarization because they are just partly ionized dust clouds from the Mira wind. We also found small faster-moving transient Halpha clouds, pointing to outflow instabilities and shocks. The observed angular shift of Halpha during the dust eclipse, can be explained by strong illumination changes from the hot component. At larger separation, the H$α$ clouds move faster (>100 km/s), in agreement with previous studies. This acceleration is probably a result of gas heating by photoionization and shocks, and the produced overpressure gives rise to the two well-known jet-like features expanding in polar directions. The presented R Aqr data are very useful to clarify the complex hydrodynamics taking place in AGB binaries.
Comments25 pages, 22 figures, accepted by Astonomy & Astrophysics
