论文标题
NGC 474与KCWI一起观看：诊断壳星系
NGC 474 as viewed with KCWI: diagnosing a shell galaxy
论文作者
论文摘要
我们介绍了使用Keck/KCWI获得的新光谱，并从星系中心和外壳的区域进行了壳星系NGC 474的运动学和恒星种群分析。我们表明，尽管具有不同的恒星种群特性，但两个区域都具有类似扩展的恒星形成历史。 NGC 474的中心区域由中等年龄的恒星（8.3 \ pm 0.3 Gyr）主导，具有生产级金属性（[z/h] = -0.24 \ pm 0.07 dex），而所观察到的壳体区域（载有一个年轻的恒星，具有平均亮度的年龄较高的恒星，sol sol-pm pm 0.5 g y 5 g y 5 g y 5 g y h h hh y n n offer-0.5 g righar gyl y n n effientive（ \ pm 0.09 dex）。我们的结果与NGC 474与Log \（（M _*/M _ \ odot）\ SIM10 \）进行中间合并的场景一致，该场景至少\ SIM 2 GYR 2 GYR，从而产生了其外壳系统。这项工作表明，低表面亮度恒星特征（例如壳）的直接光谱研究现在是可行的，并为了解星系形成和进化开辟了一个新的窗口。
We present new spectra obtained using Keck/KCWI and perform kinematics and stellar population analyses of the shell galaxy NGC 474, from both the galaxy centre and a region from the outer shell. We show that both regions have similarly extended star formation histories although with different stellar population properties. The central region of NGC 474 is dominated by intermediate-aged stars (8.3 \pm 0.3 Gyr) with subsolar metallicity ([Z/H]= -0.24 \pm 0.07 dex) while the observed shell region, which hosts a substantial population of younger stars, has a mean luminosity-weighted age of 4.0 \pm 0.5 Gyr with solar metallicities ([Z/H]=-0.03 \pm 0.09 dex). Our results are consistent with a scenario in which NGC 474 experienced a major to intermediate merger with a log\((M_*/M_\odot)\sim10 \) mass satellite galaxy at least \sim 2 Gyr ago which produced its shell system. This work shows that the direct spectroscopic study of low-surface brightness stellar features, such as shells, is now feasible and opens up a new window to understanding galaxy formation and evolution.
