The Connection between a Lyman Limit System, a very strong OVI Absorber,   and Galaxies at z~0.203
  With a column density log N(OVI) = 14.95+/-0.05, the OVI absorber at z_abs~0.2028 observed toward the QSO PKS0312-77 (z_em=0.223) is the strongest yet detected at z<0.5. At nearly identical redshift (z_abs=0.2026), we also identify a Lyman limit system (LLS, log N(HI)=18.22). Combining FUV and NUV spectra of PKS0312-77 with optical observations of galaxies in the surrounding field (15'x32'), we present an analysis of these absorbers and their connection to galaxies. The observed OI/HI ratio and photoionization modelling of other low ions indicate the metallicity of the LLS is [Z/H]_LLS=-0.6 and that the LLS is nearly 100% photoionized. In contrast, the OVI-bearing gas is collisionally ionized at T~(3-10)x10^5 K as derived from the high-ion ratios and profile broadenings. Our galaxy survey reveals 13 (0.3<L/L*<1.6) galaxies at \rho<2 h^{-1}_{70} Mpc and |\delta v|<1100 km/s from the LLS. A probable origin for the LLS is debris from a galaxy merger, which led to a 0.7L* galaxy ([Z/H]_gal=+0.15) at\rho~38 h^{-1}_{70} kpc. Outflow from this galaxy may also be responsible for the supersolar ([Z/H]_abs=+0.15), fully ionized absorber at z_abs=0.2018 (-190 km/s from the LLS). The hot OVI absorber likely probes coronal gas about the 0.7 L* galaxy and/or (~0.1 keV) intragroup gas of a spiral-rich system. The association of other strong OVI absorbers with LLS suggests they trace galactic and not intergalactic structures. 
N. Lehner, J.X. Prochaska, H.A. Kobulnicky, K.L. Cooksey, J.C. Howk,   G.M. Williger, S.L. Cales