... ESO, the European Southern Observatory . ... ESO Acronyms . ... Images . ... Galaxies . Galaxy Clusters . ... This image from the NASA/ESA Hubble Space Telescope shows the rich galaxy cluster Abell 3827. ... The distribution of dark matter in the cluster is shown with blue contour lines. The dark matter clump for the galaxy at the left is significantly displaced from the position of the galaxy itself, possibly implying dark matter-dark matter interactions of an unknown nature are occuring. ...

Astronotes Armagh Planetarium's Stellar Blog! ... Armagh Planetarium . ... Stars . ... Space Flight . ... Monthly Sky Notes . ... By admin October 1, 2010 Posted in: Stars . A sky of blazing stars (Image Credit: NASA/ESA) . Imagine that once the Sun sets, rather than a dark sky sprinkled with a few thousand dim stars, we had a sky blazing with ten thousand or so stars blazing brighter than Venus. ... Planets orbiting stars in the NGC 3603 Young Cluster would experience just such a sky. ...

Last time we saw that flat rotation curves for galaxies, when measured in galaxies with extended gas distributions, provides unambiguous data that shows the mass distribution is dominated by an unseen, spherical halo. ... Perhaps only galaxies with extended dark matter halos are capable of retaining large gaseous extents? . ... Clusters of Galaxies: . ... The case of the Cancer cluster: . ... Below is the velocity distribution of galaxies in the Cancer cluster: . ... What's going on in Cancer? ...

This collage shows images of six different galaxy clusters taken with NASA's Hubble Space Telescope and Chandra X-ray Observatory. The clusters were observed in a study of how dark matter in clusters of galaxies behaves when the clusters collide. ... Using visible-light images from Hubble, the team was able to map the post-collision distribution of stars and also of the dark matter (colored in blue), which was traced through its gravitational lensing effects on background light. ...

Today's APOD | ... Galaxies rotate and move in clusters as if a tremendous amount of unseen matter is present. ... Specifically, present analyses of above WMAP all-sky image indicate that the universe is 13.7 billion years old (accurate to 1 percent), composed of 73 percent dark energy , 23 percent cold dark matter , and only 4 percent atoms , is currently expanding at the rate of 71 km/sec/ Mpc (accurate to 5 percent), underwent episodes of rapid expansion called inflation , and will expand forever . ...

... Dark Matter Ring Modeled around Galaxy Cluster CL0024 17 . ... A new observation of gravitationally magnified faint galaxies far in the distance behind a massive cluster of galaxies is shedding new dark on the subject. ... A hypothesis for the formation of the huge dark matter ring holds that it is a transient feature formed when galaxy cluster CL0024+17 collided with another cluster of galaxies about one billion years ago, leaving a ring similar to when a rock is thrown in a pond. ...

... Using simulated clusters and Markov Chain Monte Carlo sampling of the probability distribution functions, we show that estimates of the MF slope, ЮБ, are unbiased and that the uncertainty, Ю?ЮБ, depends primarily on the number of observed stars and on the range of stellar masses they span, assuming that the uncertainties on individual masses and the completeness are both well characterized. ...

The Mass-Density of the Universe and the Distribution of Dark Matter Neta A. Bahcall Princeton University, USA One of the most fundamental questions of cosmology is: How much matter is there in the Universe and how is it distributed? Here we show that several independent measures - including those utilizing clusters of galaxies - all indicate that the mass-density of the Universe is low: only 20-30% of the critical density. ... The results reveal a low den- sity of 0.16+-0.05. ...

... October 21, 1997 This Hubble Space Telescope image provides a detailed look at a brilliant "fireworks show" at the center of a collision between two galaxies. ... The respective cores of the twin galaxies are the orange blobs, left and right of image center, crisscrossed by filaments of dark dust. A wide band of chaotic dust, called the overlap region, stretches between the cores of the two galaxies. ...

Astronomy Education News . ... T he SELB Schools Cluster Programme is an innovative learning strategy developed by the Armagh Rhymers in collaboration with the Armagh Observatory to teach children science and the arts in a new and fun way. During this programme, children from seven schools in Armagh have learnt astronomy through storytelling and music; and creative writing and music through science and astronomy. ... Schools involved: . ... Armagh Observatory - Astronomy Education . ...

... Feeding the Monster: Gas Caught in its Death Spiral into a Massive Black Hole . ... Stromlo Professor Mike Dopita have used the Hubble Space Telescope to discover how a massive Black Hole in a nearby galaxy feeds itself. ... Earlier Hubble Telescope data obtained by another team member, Professor Holland Ford of Johns Hopkins University in Baltimore, Maryland, had found a disk of gas rushing around the Black Hole at a speed of 500 kilometers a second. ...