2. The data
2.1. Optical data
Our optical analysis is based on the following data:
The total sample therefore includes 97 galaxies located within the following range of positions relative to the cluster center: X6480 and Y8710 arcsec.
2.2. X-ray data
Our X-ray study is based on a ROSAT PSPC image of ABCG 194 retrieved from the ROSAT data bank; the exposure time was 24482 seconds (P.I. Murray & Stephens). This image was processed with the Snowden software (Snowden et al. 1994). Obviously, this cluster is not a strong X-ray emitter, since in spite of the relatively high exposure time the total amount of counts is 8530, which is small. We show in Fig. 2 a superposition of the optical and X-ray maps, and in Fig. 3 that of the optical and radio maps. Notice that there is a zoom by a factor of 3 between these two images.
In X-rays, the signal to noise ratio is low: we give in Fig. 4 the curves which allow us to obtain the number of pixels above a certain count level. 99% of the pixels contain only 1 or 2 counts (essentially noise) for both clusters; however, there are much more pixels with a large number of counts (essentially signal) in ABCG 85 than in ABCG 194.
2.3. Radio data
In the center of this cluster are located the radiosources 0123-016A and 0123-016B. The "dumbbell" source 0123-016A coincides with two galaxies, one of them being NGC 547 (3C 40), while 0123-016B coincides with NGC 541 (Ledlow & Owen 1995, Edge & Röttgering 1995); NGC 547 and NGC 541 are the first are third magnitude galaxies in the cluster respectively. The radiosource 3C 40 has a "Twin Jet" structure (Burns et al. 1994). The optical disk of NGC 547 is perpendicular to the radio axis (Zirbel & Baum 1998) and its direction coincides with that joining NGC 541 and 547 (Fasano et al. 1996). NGC 541 is a narrow-angle-tailed (NAT) radio galaxy. The direction of the tail coincides with that between NGC 541 and 547 (O'Dea & Owen 1985). According to Brodie et al. (1985) and van Breugel et al. (1985), this radio source may be interacting with Minkowski's object.
© European Southern Observatory (ESO) 1999
Online publication: August 25, 1999