Showing papers on "Mass segregation published in 1991"

Star counts, blue stragglers, and mass segregation in NGC 7492

Abstract: New B, V photometry of the sparse globular cluster NGC 7492 is used to construct the cluster color-magnitude diagram (CMD) down to about three magnitudes below the main-sequence turnoff. Adopting a reddening of E(B-V) = 0.00 mag, the cluster metallicity is confirmed to be [Fe/H] = −1.51. The relative-age technique of VandenBerg et al. (1990, Astron. J., 100) implies that NGC 7492 is approximately 1.7 ± 1.2 Gyr older than NGC 6752. A distance modulus of (m-M) 0 = 17.09 ± 0.20 mag has been derived. The discovery of 27 candidate blue stragglers which are found to be more centrally concentrated than the cluster subgiants of similar brightness is reported

Luminosity segregation as an indication of dynamical evolution in rich clusters of galaxies

Abstract: The luminosity segregation in several galaxy clusters has been analyzed by means of the intergalactic distance distribution function, corrected from the masking effects of field galaxies. It has been found that the clusters present a gradation of luminosity segregation, from highly segregated to virtually not segregated. In order to understand these results, simulations of the dynamical evolution of galaxy clusters have been carried out by means of the Fokker-Planck equation moments method. It is concluded that the observed mass segregation could be due to dynamical evolution during the two-body relaxation phase, and that their different degrees could be a reflection of either the different initial conditions present at the onset of this phase or different cluster ages. 65 refs.