2014AJ....148..103K

We present new GALEX images and optical spectroscopy of J1229+02, a dwarf post-starburst galaxy located 81 kpc from the 1585 km/s absorber in the 3C 273 sight line. The absence of H_α emission and the faint GALEX UV fluxes confirm that the galaxy's recent star formation rate is < 10^–3M_☉/yr. Absorption-line strengths and the UV{#8722}optical SED give similar estimates of the acceptable model parameters for its youngest stellar population where f_m < 60% of its total stars (by mass) formed in a burst t_sb = 0.7 -3.4 Gyr ago with a stellar metallicity of -1.7 < [Fe/H] < +0.2 ; we also estimate the stellar mass of J1229+02 to be 7.3 < log(M_*/M_☉) < 7.8. Our previous study of J1229+02 found that a supernova-driven wind was capable of expelling all of the gas from the galaxy (none is observed today) and could by itself plausibly create the nearby absorber. But, using new data, we find a significantly higher galaxy/absorber velocity difference, a younger starburst age, and a smaller starburst mass than previously reported. Simple energy-conserving wind models for J1229+02 using fiducial values of f_m ∼ 0.1, t_sb ∼ 2 Gyr, and log(M_*/M_☉)∼7.5 allow us to conclude that the galaxy alone cannot produce the observed QSO absorber; i.e., any putative ejecta must interact with ambient gas from outside J1229+02. Because J1229+02 is located in the southern extension of the Virgo cluster ample potential sources of this ambient gas exist. Based on the two nearest examples of strong metal-line absorbers discovered serendipitously (the current one and the 1700 km/s metal-line absorber in the nearby Q1230+0115 sight line), we conclude that absorbers with 10¹⁴ < N_HI< 10¹⁶/cm2 at impact parameters ≳ 1R_vir are likely intergalactic systems and cannot be identified unambiguously as the circumgalactic material of any one individual galaxy.