SIMBAD references

High resolution X-ray images of three early type galaxies observed with the ROSAT HRI are presented. Data for NGC 1553 and NGC 5846 indicate that the emission is highly irregular, with interesting features on scales from a few arcsec to a few arcmin. The gas temperatures also vary both with the galactocentric radius and in correspondence to regions of higher emission and denser material. Strikingly similar features are observed in the X-ray and Hα morphologies of NGC 1553 and NGC 5846, while smoother, more regular isophotes are observed in NGC4649 at both wavelengths. A connection between these two kinds of emission therefore seems likely. In the light of our observations we discuss possible scenarios that can account for the connection between X-ray and Hα emissions.