论文标题
通过VVVX调查，以银河系发现的新的低亮度球形集群
A new low-luminosity globular cluster discovered in the Milky Way with the VVVX survey
论文作者
论文摘要
ViaLáctea扩展调查（VVVX）中的Vista变量允许探测内部银河系（MW）的先前未开发的区域。我们正在寻找新的候选球状簇（GC），目的是完成MW GC系统的普查。我们使用近IIR VVVX调查和2个MASS数据集以及光学GAIA EDR3光度法及其精确的适当运动（PMS）的组合，搜索并表征了新的GCS。我们报告了一个名为Garro 02的新的银河GC的发现，位于RA = 18：05：51.1，DEC = -17：42：02和L = 12.042度，B =+1.656度。在执行PM污染程序的过程中，我们与所有群集成员建立了最终目录，并在其上进行了光度分析。我们计算了$ e（j-k_s）= 1.07 \ pm 0.06 $ mag和$ a_ {ks} = 0.79 \ pm 0.04 $ mag在近ir中的红色；而$ e（bp-rp）= 2.40 \ pm 0.01 $ mag和$ a_ {g} = 4.80 \ pm 0.02 $ mag in Passical Bands。它的中心距离为$ d = 5.6 \ pm 0.8 $ kpc，将Garro 02放置在$ r_g = 2.9 $ kpc的半腔室距离上，z = 0.006 kpc = 0.006 kpc。通过与已知的GC相比，我们估计了金属性和年龄，并通过拟合Parsec等速线，找到[Fe/H] $ = -1.30 \ pm 0.2 $ dex and age = $ 12 \ $ 12 \ pm 2 $ gyr。我们得出了$（μ_α^{\ ast}，μ_δ）的平均簇PM =（-6.07 \ pm 0.62，-6.15 \ pm 0.75）$ mas yr $^{ - 1} $。我们计算了$ m_ {ks} = -7.52 \ pm 1.23 $ mag的近级群集发光度，这相当于$ m_ {v} = -5.44 $ mag。径向密度曲线的核心和潮汐半径分别为$ r_c = 1.25 \ pm 0.27 $ arcmin（2.07 pc）和$ r_t = 7.13 \ pm 3.83 $ arcmin（11.82 pc）。我们确认Garro 02是位于MW Bulge中的新的真正的银河GC。这是一种低亮度，金属贫困和旧的GC，它是MW一生中发生的强大动态过程的幸运幸存者。
The VISTA Variables in the Via Láctea Extended Survey (VVVX) allows probing previously unexplored regions of the inner Milky Way (MW). We are looking for new candidate globular clusters (GCs), with the aim of completing the census of the MW GC system. We searched and characterised new GCs, using a combination of the near-IR VVVX survey and 2MASS datasets, and the optical Gaia EDR3 photometry and its precise proper motions (PMs). We report the discovery of a new Galactic GC, named Garro 02, situated at RA=18:05:51.1, Dec=-17:42:02 and l=12.042 deg, b=+1.656 deg. Performing a PM-decontamination procedure, we built a final catalogue with all cluster members, on which we performed a photometric analysis. We calculated a reddening of $E(J-K_s)=1.07\pm 0.06$ mag and extinction of $A_{Ks}=0.79\pm 0.04$ mag in the near-IR; while $E(BP-RP)=2.40\pm 0.01$ mag and $A_{G}=4.80\pm 0.02$ mag in optical passbands. Its heliocentric distance is $D=5.6\pm 0.8$ kpc, which places Garro 02 at a Galactocentric distance of $R_G=2.9$ kpc and Z=0.006 kpc above the Galactic plane. We estimated the metallicity and age by comparison with known GCs and by fitting PARSEC isochrones, finding [Fe/H]$=-1.30\pm 0.2$ dex and age=$12\pm 2$ Gyr. We derived the mean cluster PM of $(μ_α^{\ast}, μ_δ) = (-6.07\pm 0.62, -6.15\pm 0.75)$ mas yr$^{-1}$. We calculated the cluster luminosity in the near-IR of $M_{Ks}=-7.52\pm 1.23$ mag, which is equivalent to $M_{V}=-5.44$ mag. The core and tidal radii from the radial density profile are $r_c =1.25\pm 0.27$ arcmin (2.07 pc) and $r_t = 7.13\pm 3.83$ arcmin (11.82 pc), respectively. We confirm Garro 02 as a new genuine Galactic GC, located in the MW bulge. It is a low-luminosity, metal-poor, and old GC, and it is a lucky survivor of the strong dynamical processes that occurred during the MW's entire life.
