Gemini GMOS/IFU spectroscopy of NGC 1569 – I. Mapping the properties of a young star cluster and its environment
Gemini GMOS/IFU spectroscopy of NGC 1569 – I. Mapping the properties of a young star cluster and its environment
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NGC 1569 的双子座 GMOS/IFU 光谱 – I. 绘制年轻星团及其环境的特性
DOI：
10.1111/j.1365-2966.2007.12346.x
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发表时间：
2007
影响因子：
4.8
通讯作者：
J. Gallagher
中科院分区：
文献类型：
--
作者：
M. Westmoquette;K. Exter;L. Smith;J. Gallagher
我们展示了双子座-北 GMOS/IFU 对矮不规则星暴星系 NGC 1569 中心附近的年轻星团及其环境的观测。这是对银河风的形成和准直机制进行的更大规模研究的一部分，包括 NGC 1569 中覆盖银河风底部的三个额外的 IFU 指向，这些点在另一篇论文中进行了分析。这些 GMOS/IFU 观测结果具有良好的空间和光谱分辨率（覆盖 4740-6860 A），使我们能够在小尺度上探测星团及其环境之间的相互作用。对于星团 10，我们将 GMOS 光谱与哈勃太空望远镜成像相结合，得出其属性。我们发现它由两个非常接近的组分组成，年龄分别为 5‐7 Myr 和 5 Myr，总质量为 7 ± 5 × 10 3 M�。强烈的红色沃尔夫-拉叶发射特征证实了我们年轻的衍生星团年龄。对整个视场的Hα发射线轮廓形状的详细分析表明，它们是由一个明亮的窄特征[固有半高全宽（FWHM）∼50 km s -1 ]叠加在较暗的宽成分（FWHM300 km s -1 ）上组成。通过绘制每个单独成分的特性，我们研究了电离星际介质的小尺度结构和特性，包括红化、激发和电子密度，并首次发现了线成分特性之间的空间相关性。我们详细讨论了可能产生这两个成分和这些相关性的可能机制，并得出结论，对广泛发射的最可能的解释是，它是在嵌入热、快速流动的星团风中的冷气团表面的湍流混合层中产生的。我们讨论在这些情况下对流动质量负载的影响。与线宽相比，窄分量和宽分量之间的平均径向速度差很小，这意味着在 IFU 视场内，湍流运动比大规模整体运动占主导地位。因此，我们在膨胀的超级气泡的外部边界冲击和流出的“能量注入区”内进行了很好的采样。
We present Gemini-North GMOS/IFU observations of a young star cluster and its environment near the centre of the dwarf irregular starburst galaxy NGC 1569. This forms part of a larger and ongoing study of the formation and collimation mechanisms of galactic winds, including three additional IFU pointings in NGC 1569 covering the base of the galactic wind which are analysed in a companion paper. The good spatial and spectral resolution of these GMOS/IFU observations, covering 4740‐6860 A, allow us to probe the interactions between clusters and their environments on small scales. For cluster 10, we combine the GMOS spectrum with Hubble Space Telescopeimaging to derive its properties. We find that it is composed of two very close components with ages of 5‐7 Myr and5 Myr, and a combined mass of 7 ± 5 × 10 3 M� . A strong red Wolf‐Rayet emission feature confirms our young derived cluster ages. A detailed analysis of the Hα emission-line profile shapes across the whole field of view shows them to be composed of a bright narrow feature [intrinsic full width at half-maximum (FWHM)∼50 km s −1 ] superimposed on a fainter broad component (FWHM300 km s −1 ). By mapping the properties of each individual component, we investigate the small-scale structure and properties of the ionized interstellar medium, including reddening, excitation and electron densities, and for the first time find spatial correlations between the line component properties. We discuss in detail the possible mechanisms that could give rise to the two components and these correlations, and conclude that the most likely explanation for the broad emission is that it is produced in a turbulent mixing layer on the surface of the cool gas clumps embedded within the hot, fast-flowing cluster winds. We discuss implications for the mass-loading of the flow under these circumstances. The average radial velocity difference between the narrow and broad components is small compared to the linewidths, implying that within the IFU field of view, turbulent motions dominate over large-scale bulk motions. We are therefore sampling well within the outer bounding shocks of the expanding superbubbles and within the outflow ‘energy injection zone’.