SIMBAD references

Recent Chandra ACIS-S observations have detected a point source at the central star of NGC 6543 and confirmed the point-source nature of the hard X-ray emission from NGC 7293. The X-ray spectra of both sources peak between 0.5 and 1.0 keV and show line features indicating a thin plasma at temperatures of a few times 10⁶ K. Their X-ray luminosities are 10³⁰ and 3x10²⁹ ergs.s^–1, respectively. We have considered four different mechanisms to explain the nature of these sources. The X-ray emission from the central star of NGC 6543 may originate from the coronal activity of an undetected companion star or from shocks in its fast stellar wind, while the hard X-ray emission from NGC 7293 might be ascribed to an undetected dMe companion. Follow-up observations are needed to determine the existence and natures of these stellar companions.