We present the first detailed analysis of the chemical abundances , ionization state , and origin of a partial Lyman limit system ( N ( \mbox { $ { H I } $ } ) \approx 10 ^ { 16 } { cm ^ { -2 } } ) at low redshift ( z = 0.167 towards PKS0405 - 1219 ) .
Two galaxies at \approx 70 h ^ { -1 } kpc projected distance to the QSO have been identified at the absorber redshift .
We analyze an echelle spectrum of the QSO obtained with the Space Telescope Imaging Spectrograph and find that this absorption system exhibits associated lines produced by C ^ { + } , N ^ { + } , O ^ { 0 } , Si ^ { + } , Si ^ { + + } , Si ^ { +3 } , Fe ^ { + } , and Fe ^ { + + } , and most interestingly , O ^ { +5 } and N ^ { +4 } .
The results of our analysis show that the partial Lyman limit system traced by various ions is likely to be embedded in a collisionally ionized { O VI } gas of larger spatial extent .
Furthermore , the partial Lyman limit system appears to have a metallicity of at least 1 / 10 solar and most likely solar or super solar despite the fact that no luminous galaxies are seen within a projected distance \rho = 60 h ^ { -1 } kpc to the QSO .
Finally , adopting the temperature estimated for the hot gas T \approx 2.5 \times 10 ^ { 5 } K and assuming a simple isothermal halo , we estimate that the galaxy or galaxy group that supports the extended gas may have a total mass \approx 1.5 \times 10 ^ { 12 } M _ { \odot } and a gas number density \lesssim 3 \times 10 ^ { -5 } cm ^ { -3 } .