A damped Ly-alpha candidate at z~0.1 toward Q 0439-433

Abstract

We report on the detection of a z_gal=0.101 galaxy projected on the sky at 4.2 arcsec (or 5.2 h^{-1} kpc for q_o=0.5) from the quasar Q 0439-433 (z_em=0.594). The HST spectrum of the quasar shows strong MgII, FeII, SiII, AlII and CIV absorption lines at the same redshift as the galaxy. The equivalent width ratios of the low ionization lines indicate that this system is probably damped with a neutral hydrogen column density of N_HI~10^{20}cm^{-2}. The CIV doublet presents a complex structure, and in particular a satellite with a velocity v=1100km/s relative to the galaxy. Additional HST and redshifted 21cm observations of this QSO-galaxy pair would offer an ideal opportunity to study the morphology of a damped absorber and the kinematics of the halo of a low-redshift galaxy.