Cosmic-Lab. Probing globular cluster internal dynamics: radial velocity dispersion and rotation profiles of 30 Galactic globular clusters

This release includes about 5400 spectra of individual stars in 30 Galactic globular clusters (GGCs) acquired within the ESO Large Program 193.D-0232, by using the K-band Multi Object Spectrograph (KMOS) mounted at the UT1 telescope of the ESO-VLT. We have used the YJ grating that provides spectra in the wavelength range 1.0-1.35 μm (10000-13500 Å), with a resolution R~3400. By using the KMOS Arm Allocator (KARMA), we allocated the available 24 IFUs to sample giant stars brighter than 1-2 magnitudes below the horizontal branch level (typically J<14), attaining a signal-to-noise ratio SNR>40 with the adopted exposure times. To reach enough number statistics, in each selected cluster we performed from 4 to 14 pointings. The final aim of the project is to measure the line-of-sight velocity of a statistically significant sample of individual stars in 30 GGCs, from which determining the velocity dispersion and rotation profiles of the target clusters.

本数据集发布包含30个银河球状星团（Galactic Globular Clusters, GGCs）中约5400颗单星的光谱数据，这些数据取自欧洲南方天文台（ESO）大科学项目193.D-0232，由搭载于ESO甚大望远镜（VLT）UT1望远镜的K波段多目标光谱仪（K-band Multi Object Spectrograph, KMOS）采集获得。本研究采用YJ光栅，其光谱覆盖波长范围为1.0~1.35 μm（即10000~13500 Å），分辨率R≈3400。通过KMOS臂分配器（KMOS Arm Allocator, KARMA），我们为观测分配了可用的24个积分场单元（Integral Field Unit, IFU），以取样水平分支以下1~2星等的亮巨星（通常J星等小于14）；采用既定曝光时间可获得信噪比（Signal-to-Noise Ratio, SNR）大于40的观测数据。为获得足够的统计样本量，我们在每个选定的星团中开展了4至14次指向观测。本项目的最终目标是为30个银河球状星团中的统计显著性单星样本测量视向速度，进而推导目标星团的速度弥散与自转轮廓。