Abell 478

The Galaxy Cluster Abell 478

Most of the Galaxy cluster Abell 478, taken with a Yellow (Visual) filter by the
1.54m Danish Telescope at La Silla by Henning Jørgensen , Nov.95.
The Central cD galaxy dominates :) the picture and as can be seen, it is surrounded by a multitude of lesser galaxies and a scattering of field stars. (please ignore the SW-NE streak across the picture, possibly a jettisoned fueltank or some similar space junk :)
According to our calculations, the cluster is receeding at a velocity of about 25000 km/s., yielding a distance of the order 250 MPc (Ho=100 MPc/Km/s).

The Center of Abell 478

The central emission-region of the center of the dominating cD galaxy of A478, viewed as the difference between the emission of the primary Balmer linie and the continuum. The dimensions of the yellow region is about 6x4 kPc.
Four spectra covering the main features of this region has been obtained by Leif Hansen on the Danish 1.54m using the DFOSC-instrument in January 1996.

The apparent 'horseshoe' structure in the emission-region has been cause for some speculation, but our preliminary analysis of the kinematical data does, with some confidence, rule out that the structure has formed through an ongoing merging process between the cD 'cannibal' galaxy and a lesser companion. So although the merging-theory is readily presenting itself when considering the morphology of the system, some other process has to account for the appearent seperation of the two main concentrations.

Absorption through obscuring dust-lanes lying in front of the object, can be ruled out too, due to the smooth ekstinction-distribution that has been obtained for the center galaxy by finding the emission-ratio of the yellow and the red bands.
Currently we are wondering if the presence of a massive Cooling Flow or the recent formation of a high concentration of early-type, very massive stars could account for this and perhaps others of the interesting properties that presents themselves in this intriguing object.
But so far, we havn't reach'd any specific convictions, yet. :-)

Back to Brian's Homepage.

This page was last updated by brian_j@astro.ku.dk on april 12th of 1997.