Cold parsec-scale gas in a zabs~0.1 sub-DLA with disparate H2 and 21-cm
  absorption
  We present a detailed analysis of a H2-bearing metal-rich sub-damped
Lyman-alpha system at zabs = 0.10115 towards the radio-loud quasar J0441-4313,
at a projected separation of ~7.6 kpc from a star-forming galaxy. The H2, C I
and Na I absorption are much stronger in the redder of the two components seen
in the Hubble Space Telescope / Cosmic Origins Spectrograph spectrum. The best
single component fit to the strong H2 component gives log N(H2) = 16.61 +/-
0.05. However, possible hidden saturation in the medium resolution spectrum can
allow for log N(H2) to be as high as 18.9. The rotational excitation
temperature of H2 in this component is 133 +33/-22 K. Photoionization models
suggest 30-80% of the total N(H I) is associated with the strong H2 component,
that has a density <= 100 cm^-3 and is subject to a radiation field that is <=
0.5 times the Galactic mean field. The Very Large Baseline Array 1.4 GHz
continuum image of the radio source contains only 27% of the arcsecond scale
emission. Using a previously published spectrum, no 21-cm absorption is found
to be associated with the strong H2 component. This suggests that either the
N(H I) associated with this component is <= 50% of the total N(H I) or the gas
covering factor is <= 0.27. This is consistent with the results of the
photoionization model that uses UV radiation due to stars in the associated
galaxy. The 21-cm absorption previously reported from the weaker H2 component
suggests a spin temperature of <= 90 K, at odds with the weakness of H2, C I
and Na I absorption in this component. From the inferred physical and chemical
conditions, we suggest that the gas may be tracing a recent metal-rich outflow
from the host-galaxy.
