. F IGURE . 13. The (a) metallicity and (b) age distributions of the globular clusters of Galactic origin. Different shadings are used to show the thick-disk and old-halo clusters. The curves are Gaussian fits to the corresponding histograms. discussion in the text | privious figure | next figure .

... We present V and I photometry for a sample of globular cluster candidates in the Virgo galaxy M87. ... A comparison with the color distribution of globular clusters in the Milky Way shows that M87 contains a large population of red clusters that is virtually absent in our Galaxy. ... Increasingly accurate measurements of the colors and metallicities of globular clusters in distant galaxies are beginning to shed new light on, and provoke new questions about, the origin of globular cluster systems. ...

The radial distribution of metallicity of star-forming galaxies in a galaxy cluster can inform us about the mass assembly and enrichment history of the galaxy cluster. ... Both galaxy clusters are cool-core clusters at redshift z т?? ... The gas-phase metallicity of star- forming galaxies in MACS1115+01 exhibit anti-correlation with projected distance т??0.15 ТБ 0.08 dex/Mpc, whereas the radial metallicity distribution of RXJ1532+30 is statistically flat (т??0.09 ТБ 0.12 dex/Mpc). ...

Stellar Clusters are very useful laboratories for empirically studying stellar evolution. ... All cluster stars are at the same distance . All cluster stars have the same physical age . ... CM diagram Young Cluster In this case we see the Main Sequence fully represented. The blue dots represent massive stars with short main sequence lifetimes. ... Thus, identifying the most massive star which is still on the main sequence is an effective means of determining the age of a stellar cluster. ...

... This represents the first HI selected sample covering the core and the outskirts of a local cluster of galaxies. ... Optically selected samples miss a considerable number of low luminosity, low surface brightness galaxies underestimating by almost a factor 2 the number of HI rich galaxies present in the cluster volume. ... Right: The g band luminosity function for galaxies in the A1367 volume as obtained from the optically (circles) and HI (histogram) selected sample. ...

... Bisnovatyi-Kogan, Gennady S.; Merafina , Marco; Vaccarelli , Maria Rosaria; Spherically Symmetric Stellar Clusters with Anisotropy and Cutoff Energy in Momentum Distribution. ... We construct numerical models of spherically symmetric Newtonian stellar clusters with anisotropic distribution functions. ... Models of spherically symmetric relativistic stellar clusters with anisotropic distribution functions in relativistic regime are described by using Maxwellian distribution function with energy...

... 1) Studying distributions of stars of different ages in irregular and spiral galaxies we found for each galaxy a clear correlation between the age of stars and the spatial size of the subsystems of stars of this age. ... We made a stellar photometry of eight NGC 1313 fields and of its dwarf companion AM 0319-662 and studied the visible distribution of stars of different ages and of metallicity in the galaxy. ... This disappeared galaxy was the cause of the gravitational deformation of NGC 1313. ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2011 June 29 . Abell 2744: Pandora's Cluster of Galaxies . Image Credit: NASA , ESA , J. Merten ( ITA , AOB ), D. Coe ( STScI ) . ... Far from a smooth distribution, Abell 2744 not only has knots of galaxies, but the X-ray emitting hot gas (colored red) in the cluster appears distributed differently than the dark matter . ... About APOD | ...

... Abell 2744: Pandoras Cluster of Galaxies . ... Credit Copyright: NASA , ESA , J. Merten ( ITA , AOB ), D. Coe ( STScI ) Explanation: Why is this cluster of galaxies so jumbled? Far from a smooth distribution, Abell 2744 not only has knots of galaxies, but the X-ray emitting hot gas (colored red) in the cluster appears distributed differently than the dark matter . ... Publications with keywords: galaxy cluster - dark matter - hot gas . ... The Hydra Cluster of Galaxies . ...

... Archives . ... my first AAS. ... I was questioned by two attendees, acquainted before the AAS, if I can suggest them clustering methods relevant to their projects. ... classification vs. clustering or supervised learning vs. unsupervised learning : the former terms from the pairs indicate the fact that the scientist already knows types of objects in his hands. ... Tags: Classification , clustering , cosmology , spatial statistics , supervised learning , test , unsupervised learning . ...

This image from the NASA/ESA Hubble Space Telescope shows NGC 6388, a dynamically middle-aged globular cluster in the Milky Way. ... A new study using Hubble data has discovered that globular clusters of the same age can have dramatically different distributions of blue straggler stars within them, suggesting that clusters can age at substantially different rates. Credit: NASA/ESA/F. Ferraro (University of Bologna) ...