oMEGACat. I. MUSE Spectroscopy of 300,000 Stars within the Half-light Radius of ω Centauri

Abstract

Abstract Omega Centauri ( ω Cen) is the most massive globular cluster of the Milky Way and has been the focus of many studies that reveal the complexity of its stellar populations and kinematics. However, most previous studies have used photometric and spectroscopic data sets with limited spatial or magnitude coverage, while we aim to investigate it having full spatial coverage out to its half-light radius and stars ranging from the main sequence to the tip of the red giant branch. This is the first paper in a new survey of ω Cen that combines uniform imaging and spectroscopic data out to its half-light radius to study its stellar populations, kinematics, and formation history. In this paper, we present an unprecedented MUSE spectroscopic data set combining 87 new MUSE pointings with previous observations collected from guaranteed time observations. We extract spectra of more than 300,000 stars reaching more than 2 magnitudes below the main-sequence turnoff. We use these spectra to derive metallicity and line-of-sight velocity measurements and determine robust uncertainties on these quantities using repeat measurements. Applying quality cuts we achieve signal-to-noise ratios (S/Ns) of 16.47/73.51 and mean metallicity errors of 0.174/0.031 dex for the main-sequence stars (18 mag

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oMEGACat。1 .半人马座半光半径内300,000颗恒星的MUSE光谱

半人马座(ω Cen)是银河系中质量最大的球状星团，一直是许多研究的焦点，揭示了其恒星群和运动学的复杂性。然而，大多数先前的研究都使用了有限空间或星等覆盖的光度和光谱数据集，而我们的目标是研究它具有完整的空间覆盖范围到它的半光半径和恒星范围从主序到红巨星分支的尖端。这是对半人马座进行的一项新调查中的第一篇论文，该调查结合了半光半径内的均匀成像和光谱数据，研究了它的恒星数量、运动学和形成历史。在本文中，我们提出了一个前所未有的MUSE光谱数据集，该数据集结合了87个新的MUSE点和以前从保证时间观测中收集的观测结果。我们提取了超过30万颗恒星的光谱，这些恒星在主序星关闭点以下超过2等。我们使用这些光谱来推导金属丰度和视线速度测量，并通过重复测量来确定这些量的鲁棒不确定性。通过高质量的切割，我们获得了主序星(18等、F等、625等、F等)的信噪比(S/Ns)为16.47/73.51，平均金属丰度误差为0.174/0.031指数;22等)和红巨星支星(16等< f625w <10毫克)。我们校正了原子扩散的金属丰度，并确定了前景恒星。这个庞大的光谱数据集将使未来的研究能够改变我们对半人马座的理解，使我们能够详细研究恒星的人口，年龄和运动学。

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