... The overall globular cluster population is divided by gap in the metallicity function at [Fe/H]=-1.0 into two discrete groups with well-defined maxima at [Fe/H]=-1.60?0.03 dex, and -0.60?0.04 dex. ... Clusters with extremely blue horizontal branches occupy a spherical volume of radius ~ 9 kpc, have high rotational velocities ( V rot =77?33 km/s), have substantial and equal negative radial and vertical metallicity gradients, and are, on average, the oldest group (the old-halo subsystem). ...

Fundamental parameters and time evolution of mass loss are investigated for post-main-sequence stars in the Galactic globular cluster 47 Tucanae (NGC 104). ... We confirm the cluster's distance as d = 4611+213 -200 pc and age as 12 ТБ 1 Gyr. Horizontal branch models appear to confirm that no more red giant branch mass loss occurs in 47 Tuc than in the more metal-poor Я? Centauri, though difficulties arise due to inconsistencies between the models. ...

... Structure of Data . ... Catalog . ... In SAI OCL Catalog, we introduce our work on investigation of the Milky Way system of open star clusters. The main goal of our study is a search for new clusters using huge surveys. 168 new clusters have been already discovered by us using J,H,Ks data from 2MASS point source catalog. ... For 141 new clusters, we found their physical parameters using J,H,Ks data from 2MASS catalog and, for a number of clusters, our UBVRI CCD observational magnitudes. ...

The central velocity dispersion represents the internal motions of the stars along a column crossing the center of a galaxy or star cluster. ... The catalogue of collected velocity dispersions may be accessed in HyperLeda. vdis is the velocity dispersion given in km/s. The velocity dispersion gives to some approximation the scale for the specific kinetic energy contained in in un-ordered motions and combined with the velocity of rotation it may give an estimate of the specific kinetic energy. ...

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. ...

... Commission 37: Star Clusters and Associations . Home Page . Commission 37 of the International Astronomical Union deals with all aspects of Globular Cluster, Open Cluster, and Stellar Associations research. With Commission 33 it forms Division VII of the IAU. Commission Structure . ... IAU Home Page . Open Clusters Database (maintained by J.-C. Mermilliod ) . Catalogue of Milky Way Globular Cluster Parameters (maintained by W. E. Harris ) . ...

... The most powerful and widely used methods to calculate the scattering matrix of a fractal cluster are based on the coupled dipoles methods (e.g. the Discrete Dipole Approximation, DDA) and the theory of light scattering by a cluster of spherical particles [2-4]. ... At present the procedure of calculation of the scattering matrix is well developed for both an oriented cluster of spherical particles and for chaotically oriented clusters of such particles [4]. ...

... We address a question if globular clusters (GC) in a protogalaxy could for some time evolve chemically as isolated systems, enriching themselves with heavy elements produced in first supernova events that follow initial star formation. We determine both the critical mass of a protoglobular cluster that is needed to retain the ejecta of the very first supernova, and the critical energy (i.e., number of supernovae) that is needed to expel the residual gas from a cluster of a given mass. ...

... WMAP7 -- 7 year WMAP data ( Larson at al., ... SPT -- CMB power spectrum from SPT ( Keisler et al., ... CDM -- flat Universe with cosmological constant . ... N eff 3.046 . ... WCDM -- flat Universe with dark energy . ... CDM, WMAP7+BAO+H0 +CL . CDM, WMAP7+BAO+H0+SPT +CL . ... CDM+f (1), WMAP7+SPT+BAO+H0 +CL . CDM+f (1)+N eff , WMAP7+SPT+BAO+H0 +CL . ... CDM+N eff , WMAP7+BAO+H0 +CL . ... CDM+dn/dlnk, WMAP7+BAO+H0 +CL . ... WCDM, WMAP7+SPT+BAO+H0 +CL . ... WCDM, WMAP7+SPT+BAO+H0+SNSYS +CL . ...

The new view on the population of Galactic open clusters A.E.Piskunov1, N.V.Kharchenko2, S.RЖser3, E.Schilbach3, R.-D.Scholz4 1 2 3 4 Institute of Astronomy, Moscow, Russia Main Astronomical ... Observatory, Kiev, Ukraine Astronomisches Rechen-Institut, Heidelberg, Germany Astrophysikalisches Institut Potsdam, Germany What are open clusters and what do they teach us Groups of Population I ... Cluster complexes: OCC-1 = Gould's Belt cluster complex? ...

... Programme . ... Abstract: Globular clusters can probe the formation history of galaxies by providing evidence for the chemical evolution and major episodes of star formation in their host galaxies, by examining their kinematic signatures, as well as their structural parameters. ... The giant elliptical NGC 5128 (Centaurus A), at a mere 4 Mpc away, gives us the only opportunity to study in extensive detail the globular cluster system of a recent merger galaxy. ...

... Subject and Problems of Stellar Astronomy. ... Plane of Galaxy, Methods of Its Location Determination. ... Stars Distances. ... Other Methods of Stars Distances Determination. ... Tangential Velocities, Their Determination by Self-Motions. ... Determination of Solar Apex and Spatial Velocity by Radial and Spatial Velocities of Stars. ... Features of Orientation and Parameters of Peculiar Stellar Velocities Ellipsoid. ... General and Selective Light Absorption in Galaxy. ... Darc Clouds in Galaxy. ...

Today's APOD | ... Editor's choices for the most educational Astronomy Pictures of the Day about globular clusters: . ... Explanation: Globular clusters once ruled the Milky Way . Back in the old days , back when our Galaxy first formed, perhaps thousands of globular clusters roamed our Galaxy . ... APOD: 2002 July 30 - A Star Cluster in Motion . ... Globular star clusters normally roam the halo of the Milky Way, ancient relics of our galaxy's formative years. ... Index | ... About APOD | ...

Topics covered by the IAU Symp. ... Do all galaxies have stellar halos? ... Stellar tracers of the MW halo and nearby galaxies; the stellar population of star clusters and their contribution to the galaxy halos . ... NEW: Scientific program of the IAU Symposium 317 can be downloaded here . ... GLOBAL PROPERTIES OF STELLAR HALOS FROM THE MILKY WAY TO EXTERNAL GALAXIES . ... DISCRETE CONSTITUENTS OF STELLAR HALOS IN THE MILKY WAY AND IN EXTERNAL GALAXIES : PLANETARY NEBULAE and GLOBULAR CLUSTERS . ...

... Primordial theory review : Dick Bond . Defects and the CMB review : Andy Albrecht . ... Gravitational wave contribution to CMB anisotropies : V.B. Lukash and E.V. Mikheeva . C_l from cosmic strings : Lloyd Knox . Some aspects of CMB anisotropies induced from topological defects : Mairi Sakellariadou . ... CMB anisotropies from scaling sources : Ruth Durrer . ... SZ observations I : Sarah Church . ... Holes in the microwave sky? ... Detecting cosmic strings in the CMB : James Robinson . ...

... Galactic or open star clusters are relatively young swarms of bright stars born together near the plane of our Milky Way Galaxy. Separated by about a degree on the sky, two nice examples are M46 (upper left) 5,400 light-years in the distance and M47 (lower right) only 1,600 light-years away toward the nautical constellation Puppis . Around 300 million years young M46 contains a few hundred stars in a region about 30 light-years across. ... M7: Open Star Cluster in Scorpius . ...

... galaxies: bulges galaxies: clusters: general galaxies: clusters: individual: . ... star formation statistics stellar content structure Cosmology ( cosmology :) cosmic background radiation ( cosmology :) cosmological parameters cosmology : miscellaneous cosmology : observations cosmology : theory ( cosmology :) dark ages, reionization, first stars ( cosmology :) dark energy ( cosmology :) dark matter ( cosmology :) diffuse radiation ( cosmology :) distance scale ( cosmology :) early Universe (...

... Gravitational wave search provides insights into galaxy evolution and mergers . ... galaxies . ... Globular cluster NGC 2808, elliptical galaxy NGC 2986, and the Sextans Dwarf . ... Open cluster NGC 2818, spiral galaxy NGC 2964, and spiral galaxy NGC 2976 . ... What are typical star-to-star distances in globular clusters compared to stellar distances in our region of the galaxy? ... RELATED TOPICS: GLOBULAR CLUSTERS . ... Get instant access to subscriber content on Astronomy.com! ...

... Запорожский клуб АЛЬТАИР > . Catalogue of 109 new Galactic open clusters, for Cartes du Ciel . ... Cartes du Ciel - Sky Charts . ... Этот каталог является версией части каталога "J/A+A/440/403 109 new Galactic open clusters (Kharchenko+, 2005) ", а именно файла stars.dat, содержащего информацию о 26778 звездах до 14.627m , находящихся в 130 рассеяных скоплениях района Млечного Пути (Galactic Open Cluster). ... We present a list of 130 Galactic Open Clusters, found in the All-Sky . ...

Astronotes Armagh Planetarium's Stellar Blog! ... Comets and Asteroids . ... Image credit:ESO/J.Emerson/VISTA. ... However others are less pessimistic and it has even been claimed that the mysterious ?Wow! signal? received in 1977 originated from the direction M55.б  Sadly, this still unexplained pulse of radio energy originated from a location rather to the northwest of M55 so I doubt if the source was this cluster (if indeed the signal was genuinely of extraterrestrial origin). ... Mysterious Wow! ...