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. ...

... Conditions are like those inside a white dwarf. ... It is not well understood what changes are caused inside the star, but the star certainly loses mass between leaving the main sequence and becoming a helium-burning horizontal branch star. When core helium burning ends, the low mass star rejoins the asymptotic giant branch, where the hydrogen and helium burning shells interact, causing a series of thermal pulses. ... Stars less than one third of a solar mass will not ignite helium at all. ...

... Staff . ... Galaxies, AGN, Cosmology . ... A new survey of X-ray clusters of galaxies with the Swift-X-ray Telescope . ... In this framework, an international collaboration between INAF-OAA, INAF-Brera, INAF-OATs, the University for Science and Technology of China-Hefei, the University of Ferrara, and the University of Massachusetts-Amherst, is undertaking a new cluster survey using an X-ray facility that was never exploited before for this goal: the X-ray Telescope (XRT) onboard the Swift satellite...

... GSAOI Home . ... Science . ... The goal of this project is to detect the termination of the white dwarf cooling sequence in nearby open star clusters, and hence derive cluster ages that are independent of the normal main sequence turnoff method. ... The potential for accurate proper motion measurements, i.e., measurements of transverse motion across the sky, with GSAOI offers a means of overcoming this difficulty. ...

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 | ...

... 633Slee+ Fifty-eight fields near rich clusters of galaxies were surveyed with the Very Large Array using scaled arrays in the B/C and/or C/D configurations at 1.5 GHz and 4.9 GHz. The fields were centered on steep spectrum sources in or near clusters that were earlier surveyed with lower resolution telescopes. ... The columns are : . Column 1 Cluster Field (Z1518 = Zw1518.8+0747) . Column 2 distance of source from cluster centre in Abell radii . ... Column 5 1.5 GHz flux (mJy) . ...

... Color-Magnitude Diagrams Triangles: objects located less than 30" from cluster center Squares: objects located less than 60" from cluster center Dots: field objects (more than 150" from center) Hollow symbols: stars Highlighted: the red sequence for each cluster Observed in the Near Infrared .. ... BCG magnitude X = clusters presented here O = clusters in literature with 0.8<z<1.2 5 of 10 x-ray sources were confirmed with a red sequence detection RXJ1205 Color suggests redshift about 1. ...

... 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 relationship of the mass and the observed galactocentric distance R -- (a), and that of the mass and the total dissipation velocity n taken from Gnedin, Ostriker (1997) -- (b). The dotted line in diagram (a) shows the "cone of survival" according to the paper by Surdin and Arkhipova (1998) . ... The solid line is a regression stright line for the main sequence of clusters, and the dotted line parallel to it separates the sequence of clusters of anomalously small mass shown by open triangles. ...

... 3C294: Distant X Ray Galaxy Cluster . ... Astronomers now realize that a hallmark of these cosmic behemoths are gas clouds with temperatures of tens of millions of degrees that pervade the clusters and radiate strongly in x-rays. This Chandra Observatory image centered on a radio galaxy cataloged as 3C294 indeed reveals the telltale hot x-ray gas in an hourglass shaped region surrounding the dominant galaxy and shows the presence of a massive galaxy cluster in the distant universe . ...

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. ...

RED SEQUENCE DWARF GALAXIES IN CLUSTERS F. G. Kopylova and A.I. Kopylov Special astrophysical observatory, Russian Academy of Sciences Red sequence galaxies in clusters are an important population for understanding galaxy formation and evolution in general. ... To study the red sequence luminosity function and dwarf-to-giant ratio (DGR), we select 10 clusters of galaxies of the Leo S