2010ApJ...722L..80F

We present new ultraviolet (UV) observations of the luminous compact blue galaxy KISSR242, obtained with the Hubble Space Telescope-Cosmic Origins Spectrograph (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. O I, C II, and Si II-Si IV 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 Si II* 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 H II regions surrounding individual star clusters. The size of the Si II* emitting region is estimated to be ≈ 250 pc. We discuss the possibility of this emission arising in overlapping super star cluster H II 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 Si II* 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.