منابع مشابه
Polar Ring Galaxies and Warps
Polar ring galaxies, where matter is in equilibrium in perpendicular orbits around spiral galaxies, are ideal objects to probe the 3D shapes of dark matter halos. The conditions to constrain the halos are that the perpendicular system does not strongly perturb the host galaxy, or that it is possible to derive back its initial shape, knowing the formation scenario of the polar ring. The formatio...
متن کاملTime evolution of galactic warps in prolate haloes
A recent observation with the Hipparcos satellite and some numerical simulations imply that the interaction between an oblate halo and a disc is inappropriate for the persistence of galactic warps. Then, we have compared the time evolution of galactic warps in a prolate halo with that in an oblate halo. The haloes were approximated as fixed potentials, while the discs were represented by N -bod...
متن کاملSpiral galaxies with large optical warps
As a result of our statistical study of 540 edgeon galaxies, we present here the images and preliminary statistical analysis of a sub-sample of 60 galaxies, that were selected to be S-type warped spirals. Computing the average volumic density of galaxies from available redshift surveys, a first analysis suggests that warped galaxies are found in denser environments. Only the clearest and strong...
متن کاملMassive Elliptical Galaxies : from Cores to Haloes
In the context of recent observational results that show massive ellipticals were in place at high redshifts, we reassess the status of monolithic collapse in a ΛCDM universe. Using a sample of over 2000 galaxies from the Sloan Digital Sky Survey, by comparing the dynamical mass and stellar mass (estimated from colours) we find that ellipticals have 'cores' which are baryon-dominated within the...
متن کاملThe Warps Survey for Faint Clusters of Galaxies
The WARPS cluster survey is based on the ROSAT PSPC archive of pointed observations. It includes extended X-ray sources, detected with the Voronoi Tessel-lation and Percolation algorithm (VTP), and point-like X-ray sources with non-stellar optical counterparts. It is designed to minimize selection eeects whilst covering a large area of sky. The aims of the survey are to (a) measure the low lumi...
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ژورنال
عنوان ژورنال: Nature
سال: 1987
ISSN: 0028-0836,1476-4687
DOI: 10.1038/328382a0