发表机构
Universidad Andres Bello; Vatican Observatory; Universidad Nacional de Córdoba; Universidade Federal de Santa Catarina; Universidad Bernardo O’Higgins; Universidad de Antofagasta; European Southern Observatory（安德斯贝洛大学; 梵蒂冈天文台; 科尔多瓦国立大学; 圣卡塔琳娜联邦大学; 贝尔纳多·奥希金斯大学; 安托法加斯塔大学; 欧洲南方天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用 KMOS VVVX-GalCen 光谱巡天的视向速度，确认了开放星团 NGC 2437 中存在未分辨三合星系统序列，并发现其比例高于较老星团，表明这些系统会合并或瓦解。
AI 中文摘要
近期光学和近红外测光数据库，如 Gaia 数据发布第三版（DR3）和 VISTA 银河系扩展变星巡天（VVVX）ESO 公共巡天，使得探索邻近星团中候选的未分辨多重系统（双星、三合星、四合星等）成为可能，这些系统需要光谱确认。NGC 2437（M 46）是一个具有良好确定的物理参数的基准开放星团。其相对较近的距离（D=1.6 kpc）使该星团成为测量未分辨多重系统比例的理想实验室。我们在此旨在识别属于开放星团 NGC 2437 的可靠成员的未分辨三合星及更高阶系统，并利用视向速度提供光谱确认。我们确认 NGC 2437 中存在一条未分辨双星序列，并报告在该星团中发现一条未分辨三合星系统序列。我们利用 ESO KMOS VVVX-GalCen 光谱巡天测量的视向速度，证实了 13 个双星系统和 8 个三合星系统的成员资格。我们进一步选择颜色与 K 型矮星一致的恒星，以获得一个与太阳邻域可比的受控样本。我们还发现，未分辨三合星和四合星的比例高于使用类似设置研究的较老开放星团 Trumpler 19，这表明这些系统会合并形成蓝离散星或随时间瓦解。我们报告了所选 VVVX 目标中 95% 的光谱确认，从而确保了 NGC 2437 中位于等质量双星序列之上的未分辨三合星系统序列的存在。单星占星团质量的 60%，而其余质量（40%）则寄居于未分辨的多重系统中。
英文摘要
Recent optical and near-IR photometric databases like Gaia data release 3 (DR3) and the VISTA Variables in the Vía Láctea eXtended (VVVX) ESO public survey allow the exploration of candidate unresolved multiple systems (binaries, triples, quadruples, etc.) in nearby clusters, that need spectroscopic confirmation. NGC 2437 (M 46) is a benchmark open cluster with well determined physical parameters. Its relative proximity (D=1.6 kpc) makes this cluster an ideal laboratory to measure the fractions of unresolved multiple systems. We aim here to identify unresolved triple and higher order systems that are reliable members of the open cluster NGC 2437, and provide the spectroscopic confirmation using radial velocities. We confirm that there is a sequence of unresolved binaries in NGC 2437, and report the discovery of a sequence of unresolved triple systems in this cluster. We corroborate membership for 13 binary systems and 8 triple systems using radial velocities measured by the ESO KMOS VVVX-GalCen spectroscopic survey. We further select stars with colors consistent with K-dwarfs, in order to have a controlled sample, comparable to the Solar neighborhood. We also find that the fraction of unresolved triples and quadruples is higher than that of the older open cluster Trumpler 19, studied using a similar setup, suggesting that these systems merge to form blue stragglers or get dissolved with time. We report the spectroscopic confirmation of 95% of the selected VVVX targets, thereby securing the presence of a sequence of unresolved triple systems in NGC 2437, located above the sequence of equal-mass binaries. The single stars constitute 60% of the mass of the cluster, while the rest of the mass (40%) is lodged in the unresolved multiple systems.
Comments8 pages, 6 figures, 1 table. Accepted for publication in A&A
