Aims. We present a comprehensive X-ray study of the population of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). Using primarily XMM-Newton observations, we conduct a systematic spectral analysis of LMC SNRs to gain new insight into their evolution and the interplay with their host galaxy. Methods. We combined all the archival XMM-Newton observations of the LMC with those of our Very Large Programme LMC survey. We produced X-ray images and spectra of 51 SNRs, out of a list of 59 objects compiled from the literature and augmented with newly found objects. Using a careful modelling of the background, we consistently analysed all the X-ray spectra and measure temperatures, luminosities, and chemical compositions. The locations of SNRs are compared to the distributions of stars, cold gas, and warm gas in the LMC, and we investigated the connection between the SNRs and their local environment, characterised by various star formation histories. We tentatively typed all LMC SNRs, in order to constrain the ratio of core-collapse to type Ia SN rates in the LMC. We also compared the column densities derived from X-ray spectra to H i maps, thus probing the three-dimensional structure of the LMC. Results. This work provides the first homogeneous catalogue of the X-ray spectral properties of SNRs in the LMC. It offers a complete census of LMC remnants whose X-ray emission exhibits Fe K lines (13% of the sample), or reveals the contribution from hot supernova ejecta (39%), which both give clues to the progenitor types. The abundances of O, Ne, Mg, Si, and Fe in the hot phase of the LMC interstellar medium are found to be between 0.2 and 0.5 times the solar values with a lower abundance ratio [α/Fe] than in the Milky Way. The current ratio of core-collapse to type Ia SN rates in the LMC is constrained to N CC /N Ia = 1.35( +0.11 −0.24 ), which is lower than in local SN surveys and galaxy clusters. Our comparison of the X-ray luminosity functions of SNRs in Local Group galaxies (LMC, SMC, M31, and M33) reveals an intriguing excess of bright objects in the LMC. Finally, we confirm that 30 Doradus and the LMC Bar are offset from the main disc of the LMC to the far and near sides, respectively.

We have obtained Chandra ACIS-S observations of NGC 6543, the Cat's Eye Nebula. The X-ray emission from NGC 6543 is clearly resolved into a point source at the central star and diffuse emission confined within the central elliptical shell and two extensions along the major axis. Spectral analysis of the diffuse component shows that the abundances of the X-ray-emitting gas are similar to those of the fast (1,750 km s −1 ) stellar wind but not those of the nebula. Furthermore, the temperature of this gas is ∼1.7×10 6 K, which is 100 times lower than the expected post-shock temperature of the fast stellar wind. The combination of low temperature and wind abundances is puzzling. The thermal pressure of this hot gas is about twice the pressure in the cool nebular shell; thus, the hot gas plays an essential role in the ongoing evolution of the nebula. Subject headings: planetary nebulae: general -planetary nebulae: individual (NGC 6543) -X-rays: ISM -stars: winds 1. Introduction Optical emission-line images of planetary nebulae (PNs) reveal a fascinating range of morphologies (e.g., the Hubble Space Telescope gallery of PNs 4 ), indicating complex internal structures in the nebulae. Among these PNs, NGC 6543, also known as the Cat's Eye Nebula, has perhaps the most interesting morphology. As reported by Reed et al. (1999), the Hα and [O III] λ5007 line images of NGC 6543 are similar, showing an inner shell surrounded by an envelope with multiple, interlocking, semi-circular features. The [N II] 4

We have studied the stellar and interstellar environments of two luminous X-ray sources and five ultraluminous X-ray sources (ULXs) in order to gain insight into their nature. Archival Hubble Space Telescope images were used to identify the optical counterparts of the ULXs Ho IX X-1 and NGC 1313 X-2, and to make photometric measurements of the local stellar populations of these and the luminous source IC 10 X-1. We obtained high-dispersion spectroscopic observations of the nebulae around these seven sources to search for He ii k4686 emission and to estimate the expansion velocities and kinetic energies of these nebulae. Our observations did not detect nebular He ii emission from any source, with the exception of LMC X-1; this is either because we missed the He iii regions or because the nebulae are too diffuse to produce He ii surface brightnesses that lie within our detection limit. We compare the observed ionization and kinematics of the supershells around the ULXs Ho IX X-1 and NGC 1313 X-2 with the energy feedback expected from the underlying stellar population to assess whether additional energy contributions from the ULXs are needed. In both cases, we find insufficient UV fluxes or mechanical energies from the stellar population; thus these ULXs may be partially responsible for the ionization and energetics of their supershells. All seven sources that we studied are in young stellar environments, and six of them have optical counterparts with masses k7 M ; thus, these sources are most likely high-mass X-ray binaries.