We study the star cluster population of NGC?2997, a giant spiral galaxy located at 9.5 Mpc and targeted by the Snapshot Hubble U-band Cluster Survey (SHUCS). Combining our U-band imaging from SHUCS with archival BVI imaging from the Hubble Space Telescope, we select a high confidence sample of clusters in the circumnuclear ring and disk through a combination of automatic detection procedures and visual inspection. The cluster luminosity functions in all four filters can be approximated by power laws with indices of –1.7 to –2.3. Some deviations from pure power-law shape are observed, hinting at the presence of a high-mass truncation in the cluster mass function. However, upon inspection of the cluster mass function, we find it is consistent with a pure power law of index –2.2 ± 0.2 despite a slight bend at ~2.5 × 104 M ☉. No statistically significant truncation is observed. From the cluster age distributions, we find a low rate of disruption (ζ ~ –0.1) in both the disk and circumnuclear ring. Finally, we estimate the cluster formation efficiency (Γ) over the last 100?Myr in each region, finding 7% ± 2% for the disk, 12% ± 4% for the circumnuclear ring, and 10% ± 3% for the entire UBVI footprint. This study highlights the need for wide-field UBVI coverage of galaxies to study cluster populations in detail, though a small sample of clusters can provide significant insight into the characteristics of the population.
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机译：我们研究了NGC？2997的恒星簇，NGC？2997是位于9.5 Mpc的巨型旋涡星系，并以“快照哈勃” U波段星团调查（SHUCS）为目标。将SHUCS的U波段成像与哈勃太空望远镜的档案BVI成像相结合，我们通过自动检测程序和目测检查的组合，选择了高置信度样本在核周环和磁盘上的簇。可以通过幂定律以–1.7至–2.3的指数近似估算所有四个滤波器中的簇光度函数。观察到与纯幂律形状的一些偏差，暗示簇质量函数中存在高质量截断。然而，在检查簇质量函数时，我们发现它与指数–2.2±0.2的纯幂律一致，尽管在〜2.5×104 M a处有轻微弯曲。没有观察到统计学上显着的截断。从星团年龄分布中，我们发现圆盘和核周环的破坏率低（ζ〜–0.1）。最后，我们估计每个区域中最近100？Myr的团簇形成效率（Γ），发现圆盘为7％±2％，环核为12％±4％，整个区域为10％±3％ UBVI足迹。这项研究强调了需要对银河系进行大范围的UBVI覆盖以详细研究星团种群，尽管少量的星团样本可以提供对种群特征的重要见解。
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