XMM-Newton RGS observations of the Cat’s Eye Nebula
1 Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
2 Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA
Received: 15 September 2014
Accepted: 25 October 2014
We present an analysis of XMM-Newton Reflection Grating Spectrometer (RGS) observations of the planetary nebula (PN) NGC 6543. These observations render it the second PN with high-resolution X-ray spectroscopic observations after BD +30°3639. The observations consist of 26 pointings, 14 of which included RGS observations for a total integration time of 435 ks. Many of these observations, however, were severely affected by high-background levels, and the net useful exposure time is drastically reduced to 25 ks. Only the O vii triplet at 22 Å is unambiguously detected in the RGS spectrum of NGC 6543. We find this spectrum consistent with an optically thin plasma at 0.147 keV (1.7 MK) and nebular abundances. Unlike BD +30°3639, the X-ray emission from NGC 6543 does not reveal overabundances of C and Ne. The results suggest that the N/O ratio of the hot plasma is consistent with that of the stellar wind, that is, it is lower than the nebular N/O ratio, but this result is not conclusive.
Key words: planetary nebulae: general / planetary nebulae: individual: NGC 6543 / stars: winds, outflows / X-rays: ISM
© ESO, 2015