We report the discovery from Hubble Space Telescope ACS images of an extended globular cluster, denoted by Scl-dE1 GC1, in the Sculptor Group dwarf Elliptical galaxy Scl-dE1 (Sc22). The distance of the dE is determined as 4.3 +/- 0.25 Mpc from the I magnitude of the tip of the red giant branch in the color-magnitude diagram. At this distance the half-light radius of Scl-dE1 GC1 is ~22 pc, placing it among the largest clusters known, particularly for globular clusters associated with dwarf galaxies. The absolute magnitude of Scl-dE1 GC1 is Mv = -6.7 and, to within the photometric uncertainties of the data, the cluster stellar population appears indistinguishable from that of the dE. We suggest that there may be two modes of globular cluster formation in dwarf galaxies, a "normal" mode with half-light radii of typically 3 pc, and an "extended" mode with half-light radii of ~10 pc or more.
Color-Magnitude Relations within Globular Cluster Systems of Giant Elliptical Galaxies: The Effects of Globular Cluster Mass Loss and the Stellar Initial Mass Function
The globular cluster system of the isolated elliptical NGC 6411: An old system in an intermediate-age galaxy?
利用Gemini/GMOS g ',r',i'测光方法对孤立椭圆星系NGC 6411及其球状星团(GC)系统进行了测光研究。这个星系是一个SNIA的宿主。光谱研究表明,在它的内部区域有一个中等年龄和非常富含金属的恒星星族。球状星团系统的范围约为65千秒差距。它的星群包含$700\pm45$成员,这意味着一个相当差的系统,就像通常在孤立的椭圆星系中发现的那样。颜色双峰和光度分布是旧GC系统的典型特征。过多的中间颜色的明亮GC可能证明了一个中间年龄的合并,但它们的颜色表明了一个比来自星系漫射光光谱研究的年龄更老的事件。
Nonlinear Color-Metallicity Relations of Globular Clusters. III. On the Discrepancy in Metallicity between Globular Cluster Systems and their Parent Elliptical Galaxies
We have carried out a search for substructure within the globular cluster systems of M84 (NGC 4374) and M86 (NGC 4406), two giant elliptical galaxies in the Virgo Cluster. We use wide-field (36 arcmin x 36 arcmin), multi-color broadband imaging to identify globular cluster candidates in these two galaxies as well as several other nearby lower-mass galaxies. Our analysis of the spatial locations of the globular cluster candidates reveals several substructures, including: a peak in the projected number density of globular clusters in M86 that is offset from the system center and may be at least …
From Giant H II regions and H II galaxies to globular clusters and compact dwarf ellipticals
大质量恒星形成区,如巨HII区(GHIIR)和HII半乳糖区(HIIG),是由致密的年轻大质量星团(YMC)电离的发射线系统,质量范围从$10^4$ M $_\odot$到$10^8$ M $_\odot$。我们模拟的光度和动力学演化超过哈勃时间的大规模引力束缚系统,填充绝对蓝色的星等和速度色散($M_{B}-σ$)的GHIIR和HIIG之间的紧密关系,并比较所产生的关系与旧的恒星系统之一:球状星团,椭圆星系,凸起的螺旋。经过12~Gyr的演化,它们在$σ$与M $_B$平面上的位置与初始质量不同,要么与初始质量为$M < 10^6$ M $_\odot$的系统的球状星团重合,要么与初始质量为$M >10^6$ M $_\odot$的YMC的椭圆星系、螺旋星系和超紧矮星的延续重合。在$10^6$ M $_\odot$周围的星系团质量处,$M_{B}-σ$和$M_B$ -尺寸关系的斜率变化是由于动力学演化对低质量星系团的影响更大。我们解释我们的结果作为一个指示,YMC,GHIIR和HIIG可以演变形成球状星团和超紧凑的矮椭圆星系在约12 Gyr,使今天的球状星团和超紧凑的矮椭圆星系可能已经形成的条件类似于今天的GHIIR和HIIG。
Confirmation of Enhanced Dwarf-sensitive Absorption Features in the Spectra of Massive Elliptical Galaxies: Further Evidence for a Non-universal Initial Mass Function
The SLUGGS Survey: Breaking degeneracies between dark matter, anisotropy and the IMF using globular cluster subpopulations in the giant elliptical NGC 5846
Stellar Population Properties of Ultracompact Dwarfs in M87: a Mass-metallicity Correlation Connecting Low-metallicity Globular Clusters and Compact Ellipticals
Globular clusters (GCs) are thought to be ancient relics from the early formative phase of galaxies, although their physical origin remains uncertain. GCs are most numerous around massive elliptical galaxies, where they can exhibit a broad colour dispersion, suggesting a wide metallicity spread. Here, we show that many thousands of compact and massive (~5$\times$10$^{\rm 3}-$3$\times$ 10$^{\rm 6} M_{\odot}$) star clusters have formed at an approximately steady rate over, at least, the past ~1Gyr around NGC 1275, the central giant elliptical galaxy of the Perseus cluster. Beyond ~1Gyr, these st…
We present the first photometric study of the globular cluster system (GCS) of the E galaxy NGC 3613 (Mv = -21.5, d = 30.1 Mpc), as well as the surface photometry of the host galaxy, based on Gemini/GMOS images. Being considered the central galaxy of a group, NGC 3613 inhabits a low-density environment although its intrinsic brightness is similar to the expected one for galaxies in the centre of clusters. The following characteristics are obtained for this GCS. The colour distribution is bimodal, with metal-poor globular clusters (GCs) getting slightly bluer with increasing radius. The radial …
We continue to explore the relationship between globular cluster total number, $N_{\rm GC}$, and central black hole mass, $M_\bullet$, in spiral galaxies. We present here results for the Sab galaxies NGC 3368, NGC 4736 (M 94) and NGC 4826 (M 64), and the Sm galaxy NGC 4395. The globular cluster (GC) candidate selection is based on the ($u^*$ - $i^\prime$) versus ($i^\prime$ - $K_s$) color-color diagram, and $i^\prime$-band shape parameters. We determine the $M_\bullet$ versus $N_{\rm GC}$ correlation for these spirals, plus NGC 4258, NGC 253, M 104, M 81, M 31, and the Milky Way. We also redet…
Nearby massive compact elliptical galaxies (MCEGs) are strong candidates for relic galaxies (i.e. local analogs of red nuggets at high redshifts). It is expected that the globular cluster (GC) systems of relic galaxies are dominated by red (metal-rich) GCs. NGC 1277 is known as a unique example of such a galaxy in the previous study. In this study, we search for GCs in 12 nearby MCEGs at distances of $\lesssim 100$ Mpc from the Hubble Space Telescope/Wide Field Camera 3 F814W($I_{814}$)/F160W($H_{160}$) archival images. We find that most of these MCEGs host a rich population of GCs with a colo…
Formation of a nuclear star cluster through the inspiral of globular clusters: A case study of the dwarf elliptical galaxy UGC 7346
Institute of Space Technology(太空技术研究所);National Centre of GIS and Space Applications(国家地理空间与空间应用中心);New York University Abu Dhabi(阿布扎比纽约大学);Center for Astrophysics and Space Science(天体物理学与空间科学中心);Vanderbilt University(范德堡大学);Fisk University(菲斯克大学);Nicolaus Copernicus Astronomical Centre, Polish Academy of Sciences(波兰科学院尼古拉·哥白尼天文学中心);Main Astronomical Observatory, National Academy of Sciences of Ukraine(乌克兰国家科学院主天文台)
X-ray Binary Luminosity Function Scaling Relations in Elliptical Galaxies: Evidence for Globular Cluster Seeding of Low-Mass X-ray Binaries in Galactic Fields
We address the nature and origin of Super Star Clusters (SSCs) discovered by Holtzman et al. (1992) within a radius of $\sim$$5\,\rm kpc$ from the center of NGC 1275, the giant elliptical galaxy at the center of the Perseus Cluster. We show that, in contrast with the much more numerous population of SSCs subsequently discovered up to $\sim$$30\,\rm kpc$ from the center of this galaxy, the central SSC population have maximal masses an order of magnitude higher and a mass function with a shallower power-law slope. Furthermore, whereas the outer SSC population have ages spanning a few $\rm Myr$ t…
The Ages, Metallicities and Alpha Element Enhancements of Globular Clusters in the Elliptical NGC 5128: A Homogeneous Spectroscopic Study with Gemini/GMOS