Discovery of a Metal?Line Absorber Associated with a Local Dwarf Starburst Galaxy

We present optical and near-infrared images, H I 21 cm emission maps, opticalspectroscopy, and Hubble Space Telescope/Space Telescope Imaging Spectrographultraviolet spectroscopy of the QSO/galaxy pair SBS 1122+594/IC 691. The QSOsight line lies at a position angle of 27 degrees from the minor axis of thenearby dwarf starburst galaxy IC 691 (cz_gal = 1204+-3 km/s, L_B ~ 0.09 L*,current star formation rate = 0.08-0.24 solar masses per year) and 33 kpc (6.6arcmin) from its nucleus. We find that IC 691 has an H I mass of M_HI =(3.6+-0.1) x 10^8 solar masses and a dynamical mass of M_dyn = (3.1+-0.5) x10^10 solar masses. The UV spectrum of SBS 1122+594 shows a metal-line(Ly-alpha + C IV) absorber near the redshift of IC 691 at cz_abs = 1110+-30km/s. Since IC 691 is a dwarf starburst and the SBS 1122+594 sight line lies inthe expected location for an outflowing wind, we propose that the best modelfor producing this metal-line absorber is a starburst wind from IC 691. Weplace consistent metallicity limits on IC 691 ([Z/Zsun] ~ -0.7) and themetal-line absorber ([Z/Zsun] < -0.3). We also find that the galaxy's escapevelocity at the absorber location is v_esc = 80+-10 km/s and derive a windvelocity of v_w = 160+-50 km/s. Thus, the evidence suggests that IC 691produces an unbound starburst wind that escapes from its gravitationalpotential to transport metals and energy to the surrounding intergalacticmedium.