ROSAT-HRI observations of six southern galaxy pairs

We present the detailed analysis of the X-ray data for 6 pairs, isolated or in poor groups, observed at high resolution with the ROSAT HRI. In all cas es, the stronger X-ray source is associated with the brighter early-type me mber and is extended. The extent varies from galactic to group scale, from 3 (RR 210b) to 182 kpc( RR 22a). The fainter members are detected only in t wo pairs, RR 210 and RR 259. Except for one case, no significant substructu res have been detected in the X-ray maps, possibly also as a consequence of the poor statistics. The core radii of the X-ray surface brightness profil es are in the range 1-3 kpc. The distribution of the luminosities of galaxi es in pairs encompasses a very wide range of both luminosities and L-X/L-B ratios, in spite of the very small number of objects studied so far. Our da ta provide no evidence that pair membership affects the X-ray properties of galaxies. Observation are discussed in the context of the pair/group evolu tion.