Photometric decomposition of NGC 6166

Abstract

We have used CFHT observations in Cousins B and R to probe the structure of the supergiant elliptical galaxy NGC 6166 in Abell 2199. We utilize the isophotal and aperture photometry of nuclei B and C to search for evidence of dynamical interactions with the central galaxy. In addition, we have investigated the dust component of the central galaxy.

The results from our photometry are consistent with the NGC 6166 system being composed of the large central cD galaxy, nucleus A, and two cluster galaxies passing through the center of the cluster. Nucleus B and C show none of the ellipticity or position angle changes, expected if these galaxies are being cannibalised. In addition, nucleus C has an average B - R = 1.75[plus-minus sign] 0.15 which is bluer than nucleus B, which has a B - R = 1.90[plus-minus sign] 0.22.

The computed dust mass of the central galaxy is ~ 7.0 X 10[superscript 5] M[sun symbol] from optical absorption, and 2.7 X 10[superscript 7] M[sun symbol] from IRAS fluxes. The dust mass is high, in any event, and is more like that of a spiral galaxy.

A Monte Carlo simulation shows that the tidal feature indicated by Lauer is not likely to be a projected cluster galaxy. The lack of significant structural changes in Nucleus B and C suggest a system in the early stages of merger. (Abstract shortened by UMI.)