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首页> 外文期刊>The Astrophysical journal >Confirmation of a New Metal-poor Globular Cluster in the Galactic Bulge*
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Confirmation of a New Metal-poor Globular Cluster in the Galactic Bulge*

机译:确认银河凸起中新的贫金属球状星团*

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We use deep near-IR photometry of the VISTA Variables in the Vía Láctea (VVV) Survey and deep DECam Plane Survey (DECaPS) optical photometry to confirm the physical reality of the candidate globular cluster (GC) Minni 22, which is located in the Galactic bulge. This object, which was detected as a high density region in our maps of bulge red giants, is now confirmed as a real GC based on the optical and near-IR color–magnitude diagrams. We also recover three known fundamental mode (ab type) RR Lyrae stars within 2 arcmin of the cluster center. The presence of RR Lyrae stars also seems to confirm Minni 22 as a bonafide old and metal-poor GC. We estimate a cluster reddening mag and determine its heliocentric distance D?=?7.4?±?0.3 kpc. The optical and near-IR color–magnitude diagrams reveal well-defined red giant branches in all cases, including a red giant branch bump at Ks?=?13.30?±?0.05 mag. The comparison with theoretical isochrones yields a mean metallicity of [Fe/H]?=??1.3?±?0.3 dex, and age of t?~?11.2 Gyr. This is a good example of a new low-luminosity (M V ?=??6.2 mag) GC found in the central bulge of the Milky Way. After discussing the different ways to confirm the existence of bulge GC candidates, we find that one of the best methods is to use the CMDs from the combination of the DECaPS + VVV photometries.
机译:我们在VíaLáctea(VVV)调查和DECAM平面调查(DECaPS)光学测光法中使用VISTA变量的深近红外测光法来确定候选球状星团(GC)Minni 22的物理现实,银河的凸起。该物体在我们的凸起红色巨星图中被检测为高密度区域,现在根据光学和近红外色度图被确认为真实的GC。我们还将在星团中心的2 arcmin内恢复三颗已知的基本模式(ab型)RR Lyrae星。 RR Lyrae恒星的存在似乎也证实了Minni 22是真正的旧金属贫乏GC。我们估算出一簇变红的磁极,并确定其日心距离Dα=?7.4?±?0.3kpc。光学和近红外色度图在所有情况下均显示出定义明确的红色巨型分支,包括Ks?=?13.30?±?0.05 mag处的红色巨型分支凸起。与理论等时线的比较产生[Fe / H] 3 =≤1.3≤±0.3 dex的平均金属度,和t 1〜≤11.2Gyr的年龄。这是在银河系中央凸起中发现的一种新的低发光度(M V == 6.2 mag)GC的很好的例子。在讨论了确认存在凸起的GC候选物的不同方法之后,我们发现最好的方法之一是结合使用DECaPS + VVV测光仪中的CMD。

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