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. ...

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• The Galaxy Gallery Page IX: Clusters of Galaxies
• Observational Constraints

... 87.1083Owen+ VIII/29 1400-MHz Survey of 1478 Abell Clusters of Galaxies (Owen+ 1982) ================================================================================ A 1400-MHz Survey of 1478 Abell Clusters of Galaxies Owen F.N., White R.A., Hilldrup K.C., Hanisch R.J. =1982AJ.. ... 0,] Major axis error 70- 71 A2 --- n_MajAxi *[ A, B, C,NR, ] Major axis note 73- 74 I2 arcmin MinAxi *? ... Note on dist-C: Ratio of the distance of the source from the cluster center to the corrected Abell cluster...

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• Density Determination
• Gravitational Lensing by Clusters of Galaxies
• A 20 cm VLA survey of Abell clusters of galaxies

Today's APOD | ... Editor's choices for the most educational Astronomy Pictures of the Day about open clusters: . APOD: 2006 January 9 - M45: The Pleiades Star Cluster . ... The Pleiades contains over 3000 stars, is about 400 light years away, and only 13 light years across. ... Two types of star clusters are visible in our Milky Way Galaxy : open clusters and globular clusters . ... Aged 80 million years, M47 is a smaller but looser cluster of about 50 stars spanning 10 light-years. ... Index | ...

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• APOD Index - Galaxies: Clusters of Galaxies
• APOD: 2002 November 29 - Open Star Clusters M35 and NGC 2158
• APOD: 2003 December 15 - Open Star Clusters M35 and NGC 2158

... 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 . ...

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• M46 and M47: Star Clusters Young and Old
• Wild Duck Open Cluster M11
• Open Star Clusters M35 and NGC 2158

... Kalirai and Harvey Richer of the University of British Columbia led the study, which began as an investigation of a globular star cluster in the Milky Way galaxy known as NGC 6397. ... Within the population of stars and galaxies behind NGC 6397, the Hubble image revealed a large elliptical galaxy that contains several hundred globular clusters. ... In fact, a single giant star in NGC 6397 appears 10 million times brighter than one of the distant globular clusters. ...

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• Hubble Space Telescope Observations of Globular Clusters in M87 and an Estimate
• Phase I Target Naming Conventions
• Globular Cluster NGC 5986

... In 1930, Trumpler noticed that linear diameters (LD) of open clusters increase with distance (D) from the Sun. ... Since that time, the interstellar absorption has become one of the best studied factor in astrophysics, and we may hope that current OCL distance scales are free from this LD-D correlation. To verify if this is the case we have chosen several modern OCL distance scales and test them with the same clusters and the same angular diameters that Trumpler had used back in 1930. ...

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• Globular Clusters: Self-Enrichment

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. ...

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• ASP: Globular Clusters and Satellite Galaxies: Companions to the Milky Way
• ASP: A Taste of Real Astronomy ? The ESA/ESO Astronomy Exercises

J/AstL/vol/page SAI Open Clusters Catalog (Glushkova+, 2009) ================================================================================ Automated search for star clusters in large multiband surveys. ... Color excesses E(B-V), distance moduli and ages were determined for 141 new and 27 known, but poorly studied clusters. We present the Sternberg Astronomical Institute Open Clusters Catalog (SAI OCL Catalog) of coordinates, diameters and main physical parameters of these clusters. ...

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• SAI Open Star Clusters (SAI OCL) Catalog
• SAI OCL Catalog Description
• SAI OCL Catalog Berkeley 71

... 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). ...

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• Population of Galactic globular clusters, figures
• Globular clusters with anomalously small masses, figures

... 2000 January 12 . NGC 6791: An Old, Large Open Cluster . ... Explanation: NGC 6791 is one of the oldest and largest open clusters of stars known. ... Open star cluster NGC 6791 , however, contains thousands of stars recently measured to be about 8 billion years old. ... This enigma makes NGC 6791, pictured above , one of the most studied open clusters and a possible example of how stars might evolve in the centers of galaxies. ... About APOD | ...

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• APOD: December 13, 1997 - The Coma Cluster of Galaxies
• SWXCS
• A new survey of X-ray clusters of galaxies with the Swift-X-ray Telescope

... A few weeks ago, around a galaxy far, far away, a new type of mysterious БЂњdarkБЂќ star cluster was spotted. Our Galaxy, the Milky Way, is surrounded by about 150 groups of stars, which are called globular clusters. ... A galaxy called Centaurus A (sen-TOR-us Ay) is surrounded by thousands of globular clusters. ... These globular clusters aren't the only dark object in Centaurus A, at the centre of this galaxy lies a black hole that is 55 million times more massive than our Sun! ...

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• Marina Rejkuba's Web Site
• ESO - Studying the Cosmological Evolution of Galaxy Clusters with (Sub-)mm
• ESO - Thesis Topic: Studying the first galaxy clusters with ALMA

The Cepheid P-L relation metallicity dependence, Hubble's Constant and Type Ia Supernovae. ... Univ. of Durham, U.K. Using both new UBVK data on the Galactic Open Clusters which contain Cepheids and a new analysis of the Distance Scale HST Key Project Cepheid data in external galaxies we argue that the Cepheid P-L relation has a strong metallicity dependence in both its zeropoint and its dispersion. ...

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• Astrophysics Group AMI Publications
• PPEUC Programme - Cosmic Microwave Background Workshop
• Astrophysics Group AMI Science

... 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! ...

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• Our Galaxy's oldest open clusters | Astronomy.com
• In some photographs of galaxy clusters, why are the arcs of a lensed galaxy
• stars and star clusters | Astronomy.com

... The default display type is Auto (ScanDisk ; adjusts to the current display). ... ScanTimeOut Determines whether ScanDisk should detect disk timeouts ; while performing a surface scan. ... Surface Determines whether ScanDisk will perform a surface scan: ; Never (Default) Does not perform a surface scan. ... The Prompt value causes ScanDisk to prompt you for a disk. ... The next five settings accept any of the following values: ; Prompt Causes ScanDisk to prompt you before fixing this problem. ...

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• Pulsar Highlights - A Dozen new MSPs in Globular Clusters
• The Pleiades
• GOLDMiNe: Virgo cluster optical and HI databases

ATMoB "Open Cluster Observing Award " Guidelines Purpose: To promote observing among the membership of the Amateur Telescope Makers of Boston through participation in the Open Clusters Observing Awards program. Introduction: This awards program is oriented towards visually observing open clusters above magnitude 9.9. ... It turns out that a very unprejudiced and convenient method to dermine the limiting magnitude is to count the number of visible stars in certain areas on the sky. ...

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• Amateur Telescope Makers of Boston
• Amateur Telescope Makers of Boston ATMoB Observing Awards Program

ABSOLUTE PROPER MOTIONS OF 331 OPEN CLUSTERS . ... The proper motions of stars in the fields of 331 open clusters were taken from Four-Million Star Catalog (4M-catalog) of positions and proper motions (Volchkov et al. ... The absolute proper motions for 21 young open clusters have been derived by comparison of precise relative proper motions of individual stars and their corresponding absolute proper motions. ... Sign of proper motions in RA . ... 0.0001 arcsec/yr . ... rms error in RA proper motion . ...

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... Posts tagged ?Globular Clusters? Oct 26th, 2007| 06:52 pm | ... I hope there are a paper or two drags your attentions and stimulates your thoughts in astrostatistics from arXiv. ... ArXiv] 4th week, Oct. ... Tags: Astrometry , Bayesian , Change Point , Globular Clusters , Matching , X-ray Binaries . ... This week, instead of only filtering AstroStatistics related papers from arxiv, I chose additional arxiv/astro-ph papers related to CHASC folks? astrophysical projects. ... ArXiv] 1st week, Oct. ...

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• Southern SHARC survey
• The AstroStat Slog Blog Archive my first AAS. IV. clustering
• The AstroStat Slog clusters

... Session 1 - Stars, star formation, stellar populations and planets . 9.20 10.00 . ... HST Spectroscopy of the Hottest White Dwarfs . ... Coffee break . ... Lunch break . ... A (long) look at neutron stars with HST . ... Session 2 - Nearby galaxies, bulges, spheroids, galaxy formation . ... New HST/ACS Insights into the Evolution of Star-Forming Dwarf Galaxies with Extreme Properties of Cosmological Relevance . ... Deriving properties of Lyman-break galaxies at z~3-5 using HST/VLT/Spitzer data . ...

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• The Formation and Evolution of LMC Rich Star Clusters: NGC 1818
• NICMOS/HST H-band (F160W) Images of the 30 Dor Starburst Cluster

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! ...

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• Omega Centauri: globular cluster of 300,000 stars | Astronotes
• Hubble shows us a spectacular star cluster | Astronotes

... 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]. ...

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• Database of Optical Properties -- Level: subpage