发表机构
Physical Research Laboratory; Indian Institute of Technology Gandhinagar; Johns Hopkins University; NASA Goddard Space Flight Center（物理研究实验室; 甘地纳加尔印度理工学院; 约翰斯·霍普金斯大学; 美国国家航空航天局戈达德航天飞行中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过ProtoPol光谱偏振仪对6颗共生星、18颗红巨星开展26个月多历元观测，发现多数目标连续谱偏振显著变化，是罕见的两年跨度多历元偏振数据集。
AI 中文摘要
测量连续谱及发射线特征中的偏振及其时间变异性，是探测天体源小尺度星周环境的有力手段，其空间尺度是直接成像技术无法触及的。然而，光谱偏振测量对光子的需求极高，导致相关数据集在文献中极为稀缺。本文呈现了对共生星与红巨星样本开展的多历元光谱偏振巡天结果。这些观测最初是在印度阿布山物理研究实验室（PRL）2.5米望远镜上搭载的新型中等分辨率阶梯光栅光谱偏振仪ProtoPol的性能验证阶段完成的。鉴于此类观测样本在文献中稀缺，研究人员于2024年3月至2026年5月期间，历时超过26个月对目标进行了重观测，以探究其偏振测量的时间变异性。样本包含6颗共生星和18颗红巨星。观测发现，与拉曼散射的λλ6830、7088埃特征不同，多数共生星的Hα发射未表现出显著的偏振信号；但样本中多数共生星和红巨星的连续谱偏振在不同观测历元间呈现出显著变化。本文提供的观测结果是罕见的、跨度超过两年的多历元光谱偏振数据集之一，应会受到更广泛天文界的关注。本文是两部分系列样本研究的第二部分；第一部分呈现了赫比格Ae/Be星与经典Be星的对应结果。
英文摘要
Measuring polarization and its temporal variability in the continuum and across emission features provides a powerful probe of the small-scale circumstellar environments of astrophysical sources, on spatial scales otherwise inaccessible to direct imaging techniques. However, the photon-hungry nature of spectro-polarimetry has significantly limited the availability of such datasets in the literature. Here we present the results of a multi-epoch spectro-polarimetric survey of a sample of symbiotic and red giant stars. These observations were first conducted during the performance verification phase of a recently developed medium-resolution echelle spectro-polarimeter, named ProtoPol, mounted on the Physical Research Laboratory (PRL) 2.5m telescope, Mt Abu, India. Considering the scarcity of such observing samples in the literature, the targets were re-observed over a period exceeding 26 months, from March 2024 to May 2026, in order to explore the time variability of their polarimetric measurements. Our sample comprises 6 symbiotic stars and 18 red giant stars. Our observations found that, unlike the Raman-scattered $λλ$ 6830, 7088 angstrom features, the H$α$ emission in most of the symbiotics did not exhibit any notable polarization signature. However, the continuum polarization of most symbiotics and red giants in the sample showed significant variation between observation epochs. The observations presented here constitute one of the rare multi-epoch spectro-polarimetric datasets spanning more than two years and should be of considerable interest to the broader astronomical community. This paper is Part-II of a two-part series of sample studies; corresponding results for Herbig Ae/Be and classical Be stars are presented in Part-I.
Comments23 pages, 7 figures. The manuscript has been accepted for publication in the Astronomical Journal (AJ)
