The population statistics of binary stars are an important output of star formation models. However populations of wide binaries evolve over time due to interactions within a system's birth environment and the unfolding of wide, hierarchical triple systems. Hence the wide binary populations observed in star forming regions or OB associations may not accurately reflect the wide binary populations that will eventually reach the field. We use Gaia DR2 data to select members of three open clusters, Alpha~Per, the Pleiades and Praesepe and to flag cluster members that are likely unresolved binaries due to overluminosity or elevated astrometric noise. We then identify the resolved wide binary population in each cluster, separating it from coincident pairings of unrelated cluster members. We find that these clusters have an average wide binary fraction in the 300-3000\,AU projected separation range of 2.1$\pm^{0.4}_{0.2}$\% increasing to 3.0$\pm^{0.8}_{0.7}$\% for primaries with masses in the 0.5-1.5\,$M_{\odot}$ range. This is significantly below the observed field wide binary fraction, but shows some wide binaries survive in these dynamically highly processed environments. We compare our results with another open cluster (the Hyades) and two populations of young stars that likely originated in looser associations (Young Moving Groups and the Pisces-Eridanus stream). We find that the Hyades also has a deficit of wide binaries while the products of looser associations have wide binary fractions at or above field level.

中文翻译：

---

宽双星在疏散星团中很少见

双星的数量统计是恒星形成模型的重要输出。然而，由于系统诞生环境中的相互作用和广泛的、层次化的三元系统的展开，宽双星的种群随着时间的推移而进化。因此，在恒星形成区域或 OB 关联中观察到的广泛双星族群可能无法准确反映最终将到达该领域的广泛双星族群。我们使用 Gaia DR2 数据来选择三个疏散星团 Alpha~Per、昴宿星团和 Praesepe 的成员，并标记可能由于过度发光或天体测量噪声升高而可能无法解析的双星的星团成员。然后，我们确定每个集群中已解析的宽二元种群，将其与不相关的集群成员的重合配对分开。我们发现这些簇在 300-3000\,AU 预计分离范围内的平均宽二进制分数从 2.1$\pm^{0.4}_{0.2}$\% 增加到 3.0$\pm^{0.8}_{ 0.7}$\% 对于质量在 0.5-1.5\,$M_{\odot}$ 范围内的原色。这明显低于观察到的现场宽二进制分数，但表明一些宽二进制文件在这些动态高度处理的环境中幸存下来。我们将我们的结果与另一个疏散星团（毕宿星团）和两个可能起源于松散关联的年轻恒星群（年轻移动群和双鱼座-波江流）进行比较。我们发现 Hyades 也有宽双星的缺陷，而松散联合的产物在或高于现场水平具有宽的双星分数。7}$\% 对于质量在 0.5-1.5\,$M_{\odot}$ 范围内的原色。这明显低于观察到的现场宽二进制分数，但表明一些宽二进制文件在这些动态高度处理的环境中幸存下来。我们将我们的结果与另一个疏散星团（毕宿星团）和两个可能起源于松散关联的年轻恒星群（年轻移动群和双鱼座-波江流）进行了比较。我们发现 Hyades 也有宽双星的缺陷，而松散联合的产物在或高于现场水平具有宽的双星分数。7}$\% 对于质量在 0.5-1.5\,$M_{\odot}$ 范围内的原色。这明显低于观察到的现场宽二进制分数，但表明一些宽二进制文件在这些动态高度处理的环境中幸存下来。我们将我们的结果与另一个疏散星团（毕宿星团）和两个可能起源于松散关联的年轻恒星群（年轻移动群和双鱼座-波江流）进行比较。我们发现 Hyades 也有宽双星的缺陷，而松散联合的产物在或高于现场水平具有宽的双星分数。我们将我们的结果与另一个疏散星团（毕宿星团）和两个可能起源于松散关联的年轻恒星群（年轻移动群和双鱼座-波江流）进行了比较。我们发现 Hyades 也有宽双星的缺陷，而松散联合的产物在或高于现场水平具有宽的双星分数。我们将我们的结果与另一个疏散星团（毕宿星团）和两个可能起源于松散关联的年轻恒星群（年轻移动群和双鱼座-波江流）进行比较。我们发现 Hyades 也有宽双星的缺陷，而松散联合的产物在或高于现场水平具有宽的双星分数。