... Archives . ... Another deduced conclusion from reading preprints listed in arxiv/astro-ph is that astronomers tend to confuse classification and clustering and to mix up methodologies. They tend to think any algorithms from classification or clustering analysis serve their purpose since both analysis algorithms, no matter what, look like a black box . ... Category: Algorithms , arXiv , Astro , Bad AstroStat , Cross-Cultural , Data Processing , Frequentist , Jargon , Methods , Stat | ...

... 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. ...

... We report on the preliminary results of experiments using a Bayesian cluster method to cluster objects present in photographic images of the POSS-II. ... We believe that the application of such algorithms to large-scale astronomical sky surveys can aid in cataloging the detected objects, and may even have the potential to discover new categories of objects. ... We have thus started to explore new clustering analysis and unsupervised classification techniques for this task. ...

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Spitzer Space Telescope mid-infrared spectroscopy has been obtained for 15 carbon-rich protoplanetary nebulae (PPNe) in the Large Magellanic Cloud (LMC) and for two other such stars in the Small Magellanic Cloud (SMC). Of these 17 PPNe, the unidentified 21 ѕ®m feature is strong in 7 spectra, weak in 2 spectra, and very weak or questionable in 4 spectra. ... The remaining two objects show typical carbon-rich PPNe spectra with no 21 ѕ®m features. ...

... Tonight's Sky . ... The Magazine . News . Observing . ... Gravitational wave search provides insights into galaxy evolution and mergers . ... The double star 54 Leonis, spiral galaxy NGC 3198, and emission nebula NGC 3199 . ... 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 . ... Receive news, sky-event information, observing tips, and more from Astronomy's weekly email newsletter. ...

... ESO, the European Southern Observatory . ... Travel and Contacts . Travel to ESO Headquarters . ... ESO . ... Survey Telescopes . ... ESO Supernova . ... Star Clusters . ... Stars@ESO . ... ESO 3.6-metre telescope . ... MPG/ESO 2.2-metre telescope . ... ESO 1-metre Schmidt telescope . ... Future Projects . ... This NASA/ESA Hubble Space Telescope image shows the positions of the past, present and predicted future appearances of the Refsdal supernova behind the galaxy cluster€а MACS J1149+2223 . ...

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. ...

... ATNF Home . ... About ATNF overview . ... Australia Telescope Steering Committee . ... Murchison Radio-astronomy Observatory . ... Parkes radio telescope . ... Mopra radio telescope . ... Visiting Parkes radio telescope . ... Parkes radio telescope webcam . ... Although galaxy mergers are thought to play an important role in forming elliptical galaxies, mergers in galaxy clusters have drawn less attention compared to mergers in field environments due to high peculiar velocities of cluster galaxies. ...

... Credit Copyright: Donald P. Waid ( Waid Observatory ) Explanation: Star cluster NGC 6823 is slowly turning gas clouds into stars. ... Some outer parts of the cluster, visible in the featured image 's center as the stars and pillars of emission nebula NGC 6820 , contain even younger stars. ... Open star cluster NGC 6823 spans about 50 light years and lies about 6000 light years away toward the constellation of the Fox ( Vulpecula ). ... Publications with keywords: star formation . ...

... December 13, 1997 . The Coma Cluster of Galaxies . ... The Coma Cluster of Galaxies pictured is one of the densest clusters known - it contains thousands of galaxies . Each of these galaxies house billions of stars - just as our own Milky Way Galaxy does. ... In fact, the Coma Cluster is so big it takes light millions of years just to go from one side to the other! Most galaxies in Coma and other clusters are ellipticals , while most galaxies outside of clusters are spirals . ...

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. ...

Intricately structured filaments of gas and dust compose the reflection nebula seen around the Pleiades star cluster. These multiwavelength images were presented to the American Astronomical Society meeting in San Antonio, TX on January 16, 1996. Click here for the press release text . ... The Schmidt data were processed further after this photo release; better versions are now available.] Get image: 512x512 (56k) / 1024x1024 (204k) . Pleiades Far-Infrared Heated Dust Emission . ...

... Visible Distribution of Galaxies. ... Features of Elliptical, Lens-Shaped, Spiral and Irregular Galaxies. Galaxies with Bar. ... Distribution of Surface Brightness of Surface and Spiral Galaxies. ... Color Characteristics of Galaxies. ... Methods of Galaxies' Mass Determination. ... Hidden Mass of Spiral Galaxies. ... Features of Dark Matter Distribution in E and SO Galaxies. ... The Whole Number of Galaxies and Their Density by the Results of Observation on the 'Hubble' Space Telescope. ...

... Ж.Ф. Родионова, А.А.Карлов, Т.П. Скобелева и др. ... Sternberg State Astronomical Institute, 119899, Moscow, Russia; jeanna@sai.msu ru. ... Moscow State University, Vorobjovy Gory, 119899, Moscow, Russia. Brown University - Vernadsky Institute Microsymposium 34, October 8-9, 2001, Moscow, Russia . ... Rodionova J1., ... Sternberg State Astronomical Institute, Moscow University, jeanna@sai.msu.ru . ... 1 Sternberg State Astronomical Institute Lomonosov Moscow University, Russia; marss8@mail.ru . ...

Many intermediate-age star clusters in the Magellanic Clouds exhibit very unusual features in their colour-magnitude diagrams that suggest they may have formed their stars over periods spanning hundreds of millions of years per cluster. ... Nonetheless, this interpretation is enticing in the context of the formation of ancient globular clusters, which almost always exhibit puzzling abundance patterns that apparently require multiple episodes of star formation to explain. ...

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! ...

... 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 . ...

Next: The Formation and Evolution Up: NICMOS Science Previous: NICMOS Observes the Galactic . ... We have taken diffraction-limited ( 0.15") near-infrared F160W (henceforth H-band, for convenience) images with NICMOS on HST of the center of the R136 cluster (age 3.5 Myr) in the core of the 30 Dor giant HII region in the Large Magellanic Cloud. ... 1996, ApJ 466, 274) can sample only M >2M , while previous V and I band HST images with WFPC2 (Hunter et al. ...

... If finddead =Y, embadpixfind looks for too dark pixels, rows and columns too. ... The maxratio parameter avoids detecting 'grey' pixels, rows or columns on observations with high statistics. Whatever findbright and finddead , dark and bright columns and rows are always searched for together in order of decreasing significance (either positive or negative). This avoids finding spurious bright columns/rows next to very dark ones, and vice-versa. ...