... The routines implemented are CLUSTER which has 8 options for hierarchical clustering and PARTITION which carries out non--hierarchical clustering. ... The former is non--hierarchical clustering or partitioning. The latter is hierarchical clustering. Brief consideration will show that a sequence of n-1 agglomerations are needed to successively merge the two closest objects and/or clusters at each stage, so that we have a set of n (singleton) clusters, n-1 clusters, ..., 2 clusters, 1 cluster. ...

Program Number . ... Gordon Drukier, Yale University . Shooting Stars: Looking for Direct Evidence of Massive Central Black Holes in Globular Clusters . Abstract . ... Hubble Heritage Observations of Arp 148 . ... The Sloan Digital Sky Survey (SDSS) has proven a powerful tool for identifying new lens candidates, although high angular resolution HST observations are essential for confirming those candidates as genuine gravitational lensing systems (see Program GO 10886). ... Past weeks: . ...

... Editor's choices for the most educational Astronomy Pictures of the Day about clusters of galaxies: . APOD: 2006 March 21 - The Coma Cluster of Galaxies . ... APOD: 2005 November 22 - A Galactic Collision in Cluster Abell 1185 . ... A prominent example occurs on the left of the above image of the rich cluster of galaxies Abell 1185. ... Recent observations of Abell 1185 have found unusual globular clusters of stars that appear to belong only to the galaxy cluster and not to any individual galaxy. ...

... Contacts . 2012: . ... We refined the fundamental parameters of the components, the orbital periods, and the conditions of photospheric heating of the secondary component by the ultraviolet radiation of the hot component. ... The observations of the star clusters associated with ultra-luminous x-ray sources (ULXs) in four galaxies on the 6-meter and VLT telescopes have shown that all the ULXs are located within 200pc of very young star clusters (younger than 5 million years). ... Archive . ...

Clusters of galaxies are the largest gravitationally bounded structures in the Universe dominated by dark matter. We review the observational appearance and physical models of plasma structures in clusters of galaxies. ... The knowledge of the complex dynamical and feedback processes is necessary to understand the energy and matter balance as well as to constrain the role of the non-thermal components of clusters. ...

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 . ...

ATNF Home . ... About ATNF overview . ... Australia Telescope Steering Committee . ... Astrophysics graduate student programs . ... Murchison Radio-astronomy Observatory . ... Parkes radio telescope . ... Mopra radio telescope . ... The Australia Telescope National Facility Colloquium . ... The mass spectrum scales as N(M) ~ M^-1.5, similar to the mass spectra of young massive star clusters suggesting that individual molecular clouds are transformed in the starburst into individual star clusters. ...

... 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 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). ...

... The large body of near infrared observations presented in Testi et al. (1997; 1998) are analysed with the aim of characterizing the young stellar clusters surrounding Herbig Ae/Be stars. The results confirm the tendency of early Be stars to be surrounded by dense clusters of lower mass "companions", while Ae stars are never found to be associated with conspicuous groups. ... Only the most massive stars (10-20Msun) are found to be associated with dense (10^3 pc^-3) stellar clusters. ...

... 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. ...

... GSAOI Home . ... Science . ... Deep J , H , and K imaging is required of Galactic and Magellanic Cloud analogs of the super star clusters identified in starburst galaxies. ... Images of the 30 Doradus star cluster in the Large Magellanic Cloud in the visible ( left panels ) and near-infrared ( right panels ) take from the ground ( top panels ) and with the Hubble Space Telescope ( bottom panels ). The fields of the GSAOI detectors are shown as four green squares in each frame. ...

... Young Star Clusters in an Old Galaxy . ... ESO , ESA , NASA Explanation: Elliptical galaxy NGC 4365 is old, probably about 12 billion years old. ... NGC 4365's star clusters themselves appear as bright dots against a diffuse glow of unresoved starlight and fuzzy, distant background galaxies. ... Publications with keywords: NGC 4365 - Elliptical Galaxy - star cluster - star formation . Publications with words: NGC 4365 - Elliptical Galaxy - star cluster - star formation . ... NGC 602 and Beyond . ...

... 1st Announcement IAU Symposium 312 Star Clusters and Black Holes Across Cosmic Time, Beijing, China, Aug. 25-29, 2014 . ... SUBJECT: 1st Announcement IAU Symposium 312 Star Clusters and Black Holes Across Cosmic Time, Beijing, China, Aug. 25-29, 2014 . ... which will be held in Beijing, P.R. China, from August 25-29, 2014, hosted by Chinese Academy of Sciences . ... China), . ... 1st Announcement IAU Symposium 312 Star Clusters and Black Holes Across Cosmic Time, Beijing, China, Aug. ...

home publications > mercury . ... Big Clusters, Tiny Galaxies . ... Astronomers struggle to understand why giant star clusters form in the tiniest of galaxies . ... These clusters are probably young versions of globular clusters, but they are commonly called super star clusters. Seven dwarf galaxies within 16 million light-years have formed super star clusters, with one of these galaxies, NGC 1569, possessing two young clusters. ... Super star clusters have a lot to tell us about star formation. ...

Proposal Identi cation No.: A1218 Date Received: 1998-Nov- 1 23:05:09 Technical Page Proposal Type: Regular General Category: Astronomy Sub-Category: Spectroscopy Observation Category: Extragalactic Total Time Requested: 36 Hours Proposal Title: HI Evolution in Intermediate Redshift Galaxy Clusters ABSTRACT: We propose to use do test observations of the HI component of 26 intermediate redshift galaxy clusters. ... Maybe Part of the observing run. ...

... Galaxy clusters in presence of dark energy: a kinetic approach . ... The external regions of galaxy clusters may be under strong influence of the dark energy, which was discovered by observations of supernovae Ia at redshift z < 1. The presence of the dark energy in the gravitational equilibrium equation, with the Einstein ? ... diagram where equilibrium solutions are not possible. ... Galactic Cluster in the Presence of Dark Energy . ...

... The Impact of HST on European Astronomy . ... These range from the study of nearby planets, the processes of star and planet formation, the stellar and interstellar components of galaxies, the discovery that most, if not all, galactic nuclei harbor a massive black hole that profoundly affects their evolution, to the realisation that the universe as a whole is undergoing acceleration as a result of a yet unknown form of dark energy . ... Formation, structure and evolution of galaxies . ...

... Archives . ... One of the speakers from the google talk series exemplified model based clustering and mentioned the likelihood ratio test (LRT) for defining the number of clusters. ... The LRT is worthless for testing a mixture when the set of parameters is large . ... We prove in this paper that the LRT is worthless from testing a distribution against a two components mixture when the set of parameters is large. ... Category: arXiv , Bad AstroStat , CHASC , Frequentist , Stat | Comment ( RSS ) | ...

... 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. ...