3 research outputs found
Emission Line Spectroscopy of a Damped Lyman-alpha Absorbing Galaxy at z = 0.437
We present Keck/LRIS spectra of a candidate damped Lyman-alpha (DLA) galaxy
toward the QSO 3C196 (z_em = 0.871). The DLA absorption system has a redshift
of z_DLA = 0.437, and a galaxy at 1.5" from the QSO has been identified in high
resolution imaging with WFPC2/HST. We have detected emission lines of [O II]
3727A, Hbeta, [O III] 5007A, Halpha and [N II] 6584A at the absorption
redshift. Based on the emission lines, we have found the redshift of the galaxy
to be z_em = 0.4376 +/- 0.0006. The emission lines also enabled us to calculate
the extinction-corrected luminosities and metallicity indicators using
established indices based on line strengths of different emission lines. These
indicators suggest that the ISM of the DLA galaxy has a high metallicity
comparable to or perhaps twice as much as solar (e.g. 12+log (O/H) = 8.98 +/-
0.07). Based on the strengths of Halpha and on the reddening derived from the
relative strengths of Halpha and Hbeta, the star formation rate is 4.7 +/- 0.8
M_solar/yr. This places the galaxy in the range of gas-rich spiral galaxies.Comment: 24 pages, 7 figures, 2 tables, accepted for publication in A