标题： 改善PHANGS-HST星系中的星团年龄估计及其对NGC 628中星团人口统计的影响 显示英文标题

标题： Improving Star Cluster Age Estimates in PHANGS-HST Galaxies and the Impact on Cluster Demographics in NGC 628

摘要： 长期以来，在推导星族的物理性质时面临的一个难题是年龄、消光和金属丰度之间的退耦问题。 当整个星系中的所有星团都采用单一金属丰度时，这种退耦可能导致古老球状星团出现 **$`$** 致命 **$'$** 错误。 通常，大约 10% 到 20% 的在漩涡星系中探测到的星团可能由于因子十以上的错误而被赋予不正确的年龄。 本文中，我们针对 PHANGS-HST 巡天中的四个星系（NGC 628、NGC 1433、NGC 1365 和 NGC 3351）进行了试点研究。 我们描述了一种方法来校正古老球状星团的年龄测定：首先通过颜色识别候选者，然后基于较低金属丰度的解决方案重新分配年龄和消光。 我们发现，年轻的 **$`$** 闯入者 **$'$** 可以通过其 Hα 流量识别出来。 CO (2-1) 强度或尘埃的存在也可以用于此目的，但我们的测试表明它们的效果不如前者好。 成功率可以提高到 **$\sim$** 15% 的水平（将灾难性年龄估算的比例从 13%-21% 减少到 3%-8%）。 许多错误测定年龄的球状星团系统地被赋予约 100 Myr 的年龄，污染了较年轻的星团群体。 错误测定年龄的球状星团显著影响了 NGC 628 中观测到的星团年龄分布，这影响了对该星系中星团瓦解的物理解释。 对于 NGC 1365，我们还展示了如何解决第二个主要的年龄测定问题，其中具有高消光（E(B-V) **$>$** 1.5 mag）的非常年轻的星团被赋予类似古老球状星团的年龄。 最后，我们注意到在 NGC 1365 中央区域附近发现了密集的约 **$\sim$** 300 Myr 星团群体，并讨论了这一结果如何自然地来自棒旋星系的动力学特性。 显示英文摘要

摘要： A long-standing problem when deriving the physical properties of stellar populations is the degeneracy between age, reddening, and metallicity. When a single metallicity is used for all star clusters in a galaxy, this degeneracy can result in $`$catastrophic$'$ errors for old globular clusters. Typically, approximately 10 - 20 % of all clusters detected in spiral galaxies can have ages that are incorrect by a factor of ten or more. In this paper we present a pilot study for four galaxies (NGC 628, NGC 1433, NGC 1365, and NGC 3351) from the PHANGS-HST survey. We describe methods to correct the age-dating for old globular clusters, by first identifying candidates using their colors, and then reassigning ages and reddening based on a lower metallicity solution. We find that young $`$interlopers$'$ can be identified from their Halpha flux. CO (2-1) intensity or the presence of dust can also be used, but our tests show that they do not work as well. Improvements in the success fraction are possible at the $\sim$ 15 % level (reducing the fraction of catastrophic age-estimates from between 13 - 21 % to 3 - 8 %). A large fraction of the incorrectly age-dated globular clusters are systematically given ages around 100 Myr, polluting the younger populations as well. Incorrectly age-dated globular clusters significantly impact the observed cluster age distribution in NGC 628, which affects the physical interpretation of cluster disruption in this galaxy. For NGC 1365, we also demonstrate how to fix a second major age-dating problem, where very dusty young clusters with E(B-V) $>$ 1.5 mag are assigned old, globular-cluster like ages. Finally, we note the discovery of a dense population of $\sim$ 300 Myr clusters around the central region of NGC 1365. and discuss how this results naturally from the dynamics in a barred galaxy.