发表机构
INAF - Osservatorio Astronomico di Padova; INAF – Osservatorio Astrofisico di Catania; INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna; INAF - Osservatorio Astronomico di Roma; Fundación Galileo Galilei – INAF; INAF – Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所帕多瓦天文台; 意大利国家天体物理研究所卡塔尼亚天文台; 意大利国家天体物理研究所博洛尼亚天文与空间科学观测站; 意大利国家天体物理研究所罗马天文台; 伽利略基金会-意大利国家天体物理研究所; 意大利国家天体物理研究所阿切尔菲天文台）
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Gaia DR3和GALAH数据，对20个银河系弦状结构进行运动学和化学表征，发现多数含疏散星团、化学均匀，可能为蒸发或瓦解的星团或迁移结构。
AI 中文摘要
背景：最近在银河系盘中发现丝状恒星结构，引发了关于它们在星系演化背景下形成机制的疑问。目的：在这项工作中，我们旨在通过寻找这些丝状恒星结构起源和形成机制的线索，对其运动学和化学性质进行表征。方法：近期利用机器学习技术和$Gaia$数据的研究已经识别出许多此前未知的银河系弦状结构。我们将这些数据与最新Gaia DR3星表导出的运动学数据以及银河考古学与HERMES（GALAH）巡天提供的化学数据进行了交叉匹配。结果：我们发现大多数弦状结构包含一个或多个疏散星团，其运动学上比疏散星团更热（内部速度弥散在1--7 km/s范围内），但比场星更冷。18个天体在化学上呈现均匀性（$\sigma_{[Fe/H]}$ <= 0.1 dex），而两个弦状结构的[Fe/H]分布较宽，与场星相似，但平均金属丰度不同，这可能表明它们是迁移中的恒星结构。对于七个天体，GALAH观测聚焦于其内部的疏散星团，因此化学丰度不能代表整个结构。一个天体显示出沿其银经延伸方向存在化学梯度的迹象。结论：这些天体可能是正在蒸发或瓦解的疏散星团，其化学均匀性在不受束缚且膨胀的恒星云中得以保留，或者是属于一个先前形成恒星枢纽、现已瓦解的共动恒星。在少数情况下，它们似乎是缺乏化学均匀性的移动星群，可能由银河系棒或旋臂的动力学作用形成。需要更多数据来证实这些假设。
英文摘要
Context: the recent discovery of filamentary stellar structures in the Milky Way disk raises the question of their formation in the context of the Galaxy evolution. Aims: in this work, we aim to kinematically and chemically characterize several filamentary stellar structures by looking for clues about their origin and formation mechanism. Methods: recent works using machine-learning techniques and $Gaia$ data have identified many previously unknown Galactic strings. We cross-matched such data with the kinematics derived from the most recent Gaia DR3 catalog as well as chemical data provided by the Galactic Archaeology with HERMES (GALAH) survey. Results: we found that most strings contain one or more open clusters and are kinematically hotter than open clusters (with internal velocity dispersions in the 1--7 km/s range) but cooler than field stars. 18 objects appear chemically homogeneous ($σ_{[Fe/H]}$ <= 0.1 dex), while two strings have a broad [Fe/H] distribution similar to the field stars but exhibit a different mean metallicity, which may identify them as migrating stellar structures. For seven objects the GALAH observations focus on the embedded open clusters; therefore, the chemical abundances are not representative of the whole structure. An object shows clues of chemical gradients along its extension in Galactic longitude. Conclusions: these objects may be evaporating or disrupted open clusters in which the chemical homogeneity is preserved in an unbound and expanding cloud of stars or co-moving stars belonging to a former and now disrupting star formation hub. In a few cases they appear to be moving groups with no chemical homogeneity, likely formed by the dynamical action of the Galactic bar or spiral arms. More data are needed to confirm such hypotheses.
Comments15 pages, 10 figures
DOI：10.1051/0004-6361/202660934
