相关论文: Globular clusters and the formation of the outer G…
The luminosities of globular clusters are found to correlate with their half-light radii. The most luminous clusters have half-light radii r ~ 3 pc. Mean cluster luminosities are < Mv > = -6.64 +/- 0.26 for r < 2.0, < Mv > = -7.44 +/- 0.20…
The possibility that the Sagittarius dwarf spheroidal might have formed as a Searle-Zinn fragment in the outer halo of the Galaxy is discussed. Arguments in favor of this hypothesis are: (1) The luminosity distribution of globular clusters…
We report the results of a systematic photometric survey of the peripheral regions of a sample of fourteen globular clusters in the outer halo of the Milky Way at distances d_GC>25 kpc from the Galactic centre. The survey is aimed at…
Most of the globular clusters in the main body of the Galactic halo were formed almost simultaneously. However, globular cluster formation in dwarf spheroidal galaxies appears to have extended over a significant fraction of a Hubble time.…
Nine presently known "young" Galactic globular clusters, which have ages / 3 Gyr smaller than the oldest clusters of similar metallicity, all have RGC > 15 kpc. Furthermore these young globulars are found to have below-average luminosities.…
The majority of the globular clusters associated with the Sagittarius dwarf galaxy are faint. In this respect it differs significantly from the globular cluster systems surrounding typical giant galaxies. The observation that most of…
(Abridged) We investigate the hypothesis that some fraction of the globular clusters presently observed in the Galactic halo formed in external dwarf galaxies, by means of a detailed comparison between Zinn's "old halo", "young halo", and…
Luminosities and tidal radii of globular clusters have been used to estimate the perigalactic distances P of well-observed Galactic globulars that do not have collapsed cores. It is found that the cluster metallicity [Fe/H] correlates…
We use recently compiled position and velocity data for the globular cluster and planetary nebula subsystems in NGC 5128, the nearby giant elliptical, to search for evidence of past dwarf-satellite accretion events. Beyond a 10 arcmin (~11…
The possible association of Galactic globular clusters with the Sgr Stream is shortly reviewed at the light of the most recent observations of the Stream. >= 20 % of the Galactic globular clusters with R_{GC}>= 10 Kpc are found to lie…
Globular cluster systems exhibit a bewildering variety of characteristics. No single scenario appears to be able to account for the wide range of specific globular cluster frequencies that are observed in galaxies of various types. The…
We report the discovery of an extended globular cluster in a halo field in Centaurus A (NGC 5128), situated $\sim 38\kpc$ from the centre of that galaxy, imaged with the Advanced Camera for Surveys on board the Hubble Space Telescope. At…
In this paper we compare the properties of three sub-systems of Galactic globular clusters, which are defined according to metallicity and HB morphology. We focus on cluster luminosities, structures, surface brightnesses (SB) and…
The global properties of all known Galactic globular clusters are examined. The relationship between the luminosities and the metallicities of Galactic globular clusters is found to be complex. Among luminous clusters there is a correlation…
This paper reviews some recent work on the properties of the outer halos of galaxies. I particularly focus on recent and upcoming advances made with the study of globular clusters. Globular clusters can be observed out to ~100 kpc from the…
The relations between the luminosities $M_{V}$, the metallicities $[Fe/H]$, the Galactocentric radii $R$, and the central concentration indices $c$ of Galactic globular clusters are discussed. It is found that the most luminous clusters…
Color-magnitude diagrams (CMDs) derived from Hubble Space Telescope (HST) Advanced Camera for Surveys F606W,F814W photometry of 6 globular clusters (GCs) are presented. The six GCs form two loose groupings in Galactocentric distance (Rgc):…
The discovery of a large population of intra-cluster star clusters in the central region of the Hydra I and Centaurus galaxy clusters is presented. Based on deep VLT photometry (V,I), many star clusters have been identified not only around…
Globular clusters (GCs) in the outer Milky Way halo are important tracers of the assembly history of our Galaxy. Only a few of these objects show spreads in heavier elements beyond the canonical light-element variations that have…
We recently found an ultra diffuse galaxy (UDG) with a half-light radius of R_e = 2.2 kpc and little or no dark matter. The total mass of NGC1052-DF2 was measured from the radial velocities of bright compact objects that are associated with…