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 | ...

... 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 . ...

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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... 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...

Astronotes Armagh Planetarium's Stellar Blog! ... Stars . ... Starbursts are short-lived events, stars are forming so quickly that the reservoirs of interstellar gas from which stars are coalescing would be used up on a timescale much shorter than the age of the galaxy . ... Strong stellar winds from giant new stars in the starburst region combine with the blasts of supernovae to push a mighty flood of extremely hot gas, a ?superwind? from the galaxy thousands of light years into intergalactic space. ...

... From the data taken during Cycle 1, surface brightness profiles have been obtained for 13 globular clusters in M31 (Fusi Pecci et al. 1993), leading also to the detection of a central cusp in a candidate post-core-collapse cluster (Bendinelli et al. ... Surface brightness profiles obtained with VISTA. ... PSF 512 512, data matrix smaller and smaller (256 256, 128 128, 64 64), sky = 0, RMG (Fig. 3b): the derived profiles remain unaffected a part from the reduction in radial extension. ...

... Current Work ­ Attempting to understand AGN feedback in galaxy clusters AMI ­ Where does AMI fit in? ... Feedback needed to offset cooling and explain the deficit of cold, molecular gas in cluster cores. ... Some already observed with AMI ­ Ideally want to observe many more (~100 ­ 150) cooling clusters in this energetically important but often overlooked frequency range. ... If bright at 1.4GHz then observe with AMI Campaign to observe many clusters at higher frequency with GISMO (2mm). ...

... This paper ( Burke et al. 2003 ) describes the creation of one such catalogue - the Southern Serendipitous High-redshift Archival ROSAT Cluster (SHARC) survey - which covers an area of 17.7 deg 2 and consists of 32 clusters with redshifts between 0.05 and 0.7 and X-ray luminosities between 7 x 10 42 and 4 x 10 44 erg/s: the high-redshift subsample contains 16 clusters with = 0.3 and X-ray luminosities greater than 2 x 10 43 erg/s (luminosities are quoted for the 0.5 - 2.0 keV energy band). ... 1997 ...

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. ...

... Ultraluminous X-ray sources (ULXs) are located in external galaxies, their X-ray luminosities (10 39 - 10 41 erg/s) are thousand times greater than those of brightest black holes in the Galaxy. ULXs may be supercritical accretion disks around black holes of stellar masses (~10 Solar masses) like that in SS433, or they may be a hypothetical intermediate-mass black holes (hundreds - thousands Solar masses) with standard accretion disks. ... 2) The ULX progenitors were ejected from the star clusters. ...

... Bad Astronomy . ... Bitesize Astronomy . ... The next step up are true clusters, called open clusters . Open clusters (sometimes misleadingly called "galactic clusters") are groups of stars ranging in size from a few dozen stars up to tens of thousands. ... The youngest is about 1 or 2 million years old, while the oldest is about 6 or 7 billion years, making it just older than our own solar system. ... So by looking at the stars in the cluster we can tell pretty well how old they are. ...

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. ...

... 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 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. ...

... 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. ...

... LMC Project Outline . NGC 1818 Initial Results . ... The Large Magellanic Cloud (LMC) is uniquely suitable for the study of massive star clusters at all stages of evolution. By combining HST observations of these clusters with N-body models we hope to understand the origin and evolution of rich star clusters in our own Galaxy, in the LMC, and beyond. ... We aim to combine our HST observations with N-body models to understand the formation and evolution of globular clusters. ...

... How to calibrate the energy scale for higher energies of future gratings? Difficult to find astronomical targets with well defined lines. ... Source Energy Flux keV HZ 43 0.2 Bright Sirius B 0.2 HZ43 /10 RXJ1856 1 Faint Simplicity Var WD WD No No No No Yes Yes Extend Lines Point Point Point 1' Point Point Point No Point Point Yes No Yes Yes Yes Yes Point Point , jet Point Cont Cont Cont Cont Lines Cont Lines Lines Lines ...

... 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]. ...

... 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). ...