1999A&A...349....1S

Dwarf galaxies are dominated by dark matter even in the innermost regions and, therefore, provide excellent probes for the investigation of dark halos. To that purpose, we analyse ROSAT PSPC-data of the dwarf galaxy NGC 247. We focus in particular on the diffuse X-ray emission in the 1/4keV band. Assuming an isothermal density profile, we find that the mass of the hot emitting gas is about 10⁸M_☉, corresponding to ≲0.5% of the total dynamical mass of the galaxy. The total mass of NGC 247, as derived from the X-ray data agrees quite well with the value obtained from the measured rotation curve (Burlak, 1996ARep...40..621B). The X-ray profile in the 3/4keV and 1.5keV band shows an excess at a radial distance of about 15 arcmin from the center. Such a ``hump'' in the radial X-ray profile can be explained by the presence of a cluster of young low mass stars or brown dwarfs. Therefore, NGC 247 offers the possibility to observe the formation of a halo of MACHOs.