Radially extended kinematics in the S0 galaxy NGC 2768 from planetary nebulae, globular clusters and starlight
Radially extended kinematics in the S0 galaxy NGC 2768 from planetary nebulae, globular clusters and starlight
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DOI：
10.1111/j.1365-2966.2012.21877.x
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发表时间：
2012-08
影响因子：
4.8
通讯作者：
D. Forbes;A. Cortesi;V. Pota;C. Foster;A. Romanowsky;M. Merrifield;J. Brodie;J. Strader;L. Coccato;N. Napolitano
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文献类型：
--
作者：
D. Forbes;A. Cortesi;V. Pota;C. Foster;A. Romanowsky;M. Merrifield;J. Brodie;J. Strader;L. Coccato;N. Napolitano
只有少数示踪剂可用于探测超出有效半径的单个早期型星系的运动学。在这里，我们直接比较 S0 星系 NGC 2768 中的行星状星云 (PNe)、球状星团 (GC) 和星系星光速度的样本，大约为四个有效半径。使用 K 波段图像的球体到盘分解，我们将 PNe 和星光分配给盘或球体。我们发现核球 PNe 和球核星光遵循与 GC 红色亚群相同的径向密度分布，而盘 PNe 和盘星光是不同的组成部分。我们发现三个示踪剂与几个有效半径（以及内部区域的恒星数据）之间具有良好的运动学一致性。我们的运动学分析进一步支持了两个星系组成部分的独特性质。将示踪剂分为凸起和圆盘组件后，我们发现凸起是一个缓慢旋转的压力支持系统，而圆盘则显示出快速上升的旋转曲线和下降的速度分散剖面。由此产生的盘面 V rot/σ 比率类似于螺旋星系，并暗示 NGC 2768 的起源是一个转变的晚期型星系。对 S0 样本进行二分量运动学分析将有助于阐明此类星系的性质。
There are only a few tracers available to probe the kinematics of individual early-type galaxies beyond one effective radius. Here we directly compare a sample of planetary nebulae (PNe), globular clusters (GCs) and galaxy starlight velocities out to approximately four effective radii, in the S0 galaxy NGC 2768. Using a bulge-to-disc decomposition of a K-band image we assign PNe and starlight to either the disc or the bulge. We show that the bulge PNe and bulge starlight follow the same radial density distribution as the red subpopulation of GCs, whereas the disc PNe and disc starlight are distinct components. We find good kinematic agreement between the three tracers to several effective radii (and with stellar data in the inner regions). Further support for the distinct nature of the two galaxy components comes from our kinematic analysis. After separating the tracers into bulge and disc components we find the bulge to be a slowly rotating pressure-supported system, whereas the disc reveals a rapidly rising rotation curve with a declining velocity dispersion profile. The resulting V rot/σ ratio for the disc resembles that of a spiral galaxy and hints at an origin for NGC 2768 as a transformed late-type galaxy. A two-component kinematic analysis for a sample of S0s will help to elucidate the nature of this class of galaxy.