A study of the double galaxy in Abell Cluster 1775

Abstract

Photographic and photoelectric photometry are used to obtain intensity profiles of the A1775 double galaxy. The intensity profiles are fitted to the standard (c = 2.25) King models, from which composite models are constructed. The apparent core radii of the SE and NW components are found to be 2.4 kpc and 3.9 kpc respectively (H[subscript o] = 75 km/sec/Mpc). The composite models consist of isophotal contour maps and a modeled surface brightness profile along the line joining the two components. The models constructed do not fit the data very well in the outer portions of the brightness profile, in that they overestimate the amount of light coming from these regions. On the basis of the models however, it seems unlikely that the A1775 system is a superposition of two unrelated galaxies, but is more likely to be some sort of interacting system. The nature of the interaction, however, cannot be answered, nor can the existence of a large diffuse halo be demonstrated on the basis of the present data.