Cool X-ray emitting gas in the core of the Centaurus cluster of galaxies

We use a deep XMM-Newton Reflection Grating Spectrometer observation to examine the X-ray emission from the core of the Centaurus cluster of galaxies. We clearly detect Fe XVII emission at four separate wavelengths, indicating the presence of cool X-ray emitting gas in the core of the cluster. Fe ions from Fe XVII to XXIV are observed. The ratio of the Fe XVII 17.1 angstrom lines to 15.0 angstrom line and limits on O VII emission indicate a lowest detected temperature in the emitting region of 0.3 to 0.45 keV (3.5 to 5.2 x 10(6) K). The cluster also exhibits strong N VII emission, making it apparent that the N abundance is supersolar in its very central regions. Comparison of the strength of the Fe XVII lines with a solar metallicity cooling flow model in the inner 17 kpc radius gives mass deposition rates in the absence of heating of 1.6-3 M-circle dot yr(-1). Spectral fitting implies an upper limit of 0.8 M-circle dot yr(-1) below 0.4 keV, 4 M-circle dot yr(-1) below 0.8 keV and 8 M-circle dot yr(-1) below 1.6 keV. The cluster contains X-ray emitting gas over at least the range of 0.35 to 3.7 keV, a factor of more than 10 in temperature. We find that the best-fitting metallicity of the cooler components is smaller than the hotter ones, confirming that the apparent metallicity does decline within the inner 1 arcmin radius.