Low-metallicity globular clusters in the low-mass isolated spiral galaxy NGC 2403
Low-metallicity globular clusters in the low-mass isolated spiral galaxy NGC 2403
复制标题
低质量孤立螺旋星系 NGC 2403 中的低金属丰度球状星团
DOI：
10.1093/mnras/stac503
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发表时间：
2022
影响因子：
4.8
通讯作者：
Day, Jacob
中科院分区：
文献类型：
--
作者：
Forbes, Duncan A.;Ferré-Mateu, Anna;Gannon, Jonah S.;Romanowsky, Aaron J.;Carlin, Jeffrey L.;Brodie, Jean P.;Day, Jacob
低质量晚期星系的球状星团（GC）系统，如NGC 2403，迄今为止研究得很少。作为一个低质量星系（M*= 7 × 109M⊙），宇宙学模拟预测ngc2403包含很少的吸积gc，如果有的话。它也是孤立的，有一个非常不受干扰的HI盘。根据文献中的候选者，斯隆数字巡天和超级超级相机成像，我们选择了几个gc用于使用凯克宇宙网成像仪进行后续光谱分析。根据它们的径向速度和其他特性，我们确定了与这个无凸起星系的内晕或盘有关的8个真正的gc。一项恒星种群分析表明，从大爆炸后不久到现在，GC年龄的范围很广。我们发现所有的旧gc都是金属贫乏的，[Fe/H]≤- 1。观测到的gc的年龄-金属丰度关系表明，它们是由低有效产率的气体在许多Gyr内形成的，与SMC中观测到的相似。浓缩物质的外流可能是造成产量低的原因之一。我们的研究是在空间和时间上全面绘制NGC 2403星团历史的第一步，预计整个系统大约有50个gc。
The globular cluster (GC) systems of low-mass late-type galaxies, such as NGC 2403, have been poorly studied to date. As a low mass galaxy (M*= 7 × 109M⊙), cosmological simulations predict NGC 2403 to contain few, if any, accreted GCs. It is also isolated, with a remarkably undisturbed HI disc. Based on candidates from the literature, Sloan Digital Sky Survey and Hyper Suprime-Cam imaging, we selected several GCs for follow-up spectroscopy using the Keck Cosmic Web Imager. From their radial velocities and other properties, we identify eight bona-fide GCs associated with either the inner halo or the disc of this bulgeless galaxy. A stellar population analysis suggests a wide range of GC ages from shortly after the big bang until the present day. We find all of the old GCs to be metal-poor with [Fe/H] ≤ −1. The age–metallicity relation for the observed GCs suggests that they were formed over many Gyr from gas with a low effective yield, similar to that observed in the SMC. Outflows of enriched material may have contributed to the low yield. With a total system of ∼50 GCs expected, our study is the first step in fully mapping the star cluster history of NGC 2403 in both space and time.