Diffuse Far-UV Line Emission from the Low-Redshift Lyman Break Galaxy
  Analog KISSR242
  We present new ultraviolet (UV) observations of the luminous compact blue
galaxy KISSR242, obtained with the HST-COS. We identify multiple resolved
sub-arcsecond near-UV sources within the COS aperture. The far-UV spectroscopic
data show strong outflow absorption lines, consistent with feedback processes
related to an episode of massive star-formation. OI, CII, and SiII--SiIV are
observed with a mean outflow velocity v_{out} = -60 km/s. We also detect faint
fine-structure emission lines of singly ionized silicon for the first time in a
low-redshift starburst galaxy. These emissions have been seen previously in
deep Lyman break galaxy surveys at z ~ 3. The SiII* lines are at the galaxy
rest velocity, and they exhibit a quantitatively different line profile from
the absorption features. These lines have a width of ~ 75 km/s, too broad for
point-like emission sources such as the HII regions surrounding individual star
clusters. The size of the SiII* emitting region is estimated to be ~ 250 pc. We
discuss the possibility of this emission arising in overlapping super star
cluster HII regions, but find this explanation to be unlikely in light of
existing far-UV observations of local star-forming galaxies. We suggest that
the observed SiII* emission originates in a diffuse warm halo populated by
interstellar gas driven out by intense star-formation and/or accreted during a
recent interaction that may be fueling the present starburst episode in
KISSR242.
