  We extend our previous study of the cool gas responsible for the emission of
OVII X-ray lines in the cores of clusters and groups of galaxies. This is the
coolest X-ray emitting phase and connects the 10,000 K H {\alpha} emitting gas
to the million degree phase, providing a useful tool to understand cooling in
these objects. We study the location of the O VII gas and its connection to the
intermediate Fe XVII and hotter O VIII phases. We use high-resolution X-ray
grating spectra of elliptical galaxies with strong Fe XVII line emission and
detect O VII in 11 of 24 objects. Comparing the O VII detection level and
resonant scattering, which is sensitive to turbulence and temperature, suggests
that OVII is preferably found in cooler objects, where the FeXVII resonant line
is suppressed due to resonant scattering, indicating subsonic turbulence.
Although a larger sample of sources and further observations is needed to
distinguish between effects from temperature and turbulence, our results are
consistent with cooling being suppressed at high turbulence as predicted by
models of AGN feedback, gas sloshing and galactic mergers. In some objects the
OVII resonant-to-forbidden line ratio is decreased by either resonant
scattering or charge-exchange boosting the forbidden line, as we show for NGC
4636. Charge-exchange indicates interaction between neutral and ionized gas
phases. The Perseus cluster also shows a high Fe XVII forbidden-to- resonance
line ratio, which can be explained with resonant scattering by low-turbulence
cool gas in the line-of-sight.
