论文标题
Centaurus附近两个小矮星系中的金属势核之星簇暗示了球状簇的刺激性形成
Metal-poor nuclear star clusters in two dwarf galaxies near Centaurus A suggesting formation from the in-spiraling of globular clusters
论文作者
论文摘要
对成核矮星系的研究可以限制低质量星系中核星形簇（NSC）的形成和演化的情景，并为我们提供有关超紧凑型矮人星系（UCDS）的起源的见解。我们报告了在矮星kks58中发现NSC的发现，并与KK197中另一个NSC的属性一起研究了其属性。两种NSC均由半人马座组的矮椭圆形星系托管。将ESO VLT MUSE数据与VLT FORS2，CTIO BLANCO DECAM和HST ACS以及VLT UVE的高分辨率光谱相结合，我们分析了NSCS及其宿主星系的光度法，运动学和恒星种群。我们根据NSC的径向速度和靠近星系中心的位置确认成员资格。我们还确认了两个球状簇（GC）的成员资格，并检测KK197主体中的旋转。 Based on high signal-to-noise spectra taken with MUSE of the NSCs of both KKs58 and KK197 we measure low metallicities, [Fe/H] = $-1.75 \pm 0.06$ dex and [Fe/H] = $-1.84 \pm 0.05$ dex, and stellar masses of $7.3 \times 10^5 M_\odot$ and $1.0 \times 10^6 m_ \ odot $。这两种NSC都比其宿主更具金属贫困，其宿主的金属性为$ -1.35 \ pm 0.23 $ dex（KKS58）和$ -0.84 \ pm 0.12 $ dex（kk197）。这可以通过GC的素养解释为NSC形成。两种NSC的质量，大小和金属性将它们置于其他NSC中，但也将其在Centaurus群体的已知UCD中。这表明NSC可能构成低质量UCD的一部分的祖细胞，尽管它们的性质几乎与典型的GC没有区别。
Studies of nucleated dwarf galaxies can constrain the scenarios for the formation and evolution of nuclear star clusters (NSC) in low-mass galaxies and give us insights on the origin of ultra compact dwarf galaxies (UCDs). We report the discovery of a NSC in the dwarf galaxy KKs58 and investigate its properties together with those of another NSC in KK197. Both NSCs are hosted by dwarf elliptical galaxies of the Centaurus group. Combining ESO VLT MUSE data with photometry from VLT FORS2, CTIO Blanco DECam, and HST ACS, as well as high-resolution spectroscopy from VLT UVES, we analyse the photometric, kinematic and stellar population properties of the NSCs and their host galaxies. We confirm membership of the NSCs based on their radial velocities and location close to the galaxy centres. We also confirm the membership of two globular clusters (GCs) and detect oblate rotation in the main body of KK197. Based on high signal-to-noise spectra taken with MUSE of the NSCs of both KKs58 and KK197 we measure low metallicities, [Fe/H] = $-1.75 \pm 0.06$ dex and [Fe/H] = $-1.84 \pm 0.05$ dex, and stellar masses of $7.3 \times 10^5 M_\odot$ and $1.0 \times 10^6 M_\odot$, respectively. Both NSCs are more metal-poor than their hosts that have metallicities of $-1.35 \pm 0.23$ dex (KKs58) and $-0.84 \pm 0.12$ dex (KK197). This can be interpreted as NSC formation via the in-spiral of GCs. The masses, sizes and metallicities of the two NSCs place them among other NSCs, but also among the known UCDs of the Centaurus group. This indicates that NSCs might constitute the progenitors of a part of the low-mass UCDs, although their properties are almost indistinguishable from typical GCs.
