Predicted Optical/Ultraviolet Line Fluxes for the Warm Absorber in Abell 2256

Recently Miyaji et al. (1993) detected excess soft X-ray absorption in the BBXRT spectrum of the cluster A2256. The absorption was due to the K-edge of oxygen; from the observed edge energy and the redshift of the cluster, Miyaji et al. argued that the primary absorber was oxygen in an ionization state between O^+2^ and O^+4^ at a temperature in the range 0.5-5 x 10^5^ K. Such gas should produce strong UV and optical line emission. We predict the strongest UV and optical line fluxes for this X- ray absorbing gas. The strongest UV lines include Lyα, C III] λ1909, C IV λ1549, O IV] λ1401, O V] λ1218, O VI λ1034, Si III λ1207, and Si IV λ1397 lines. These lines should be detectable with the International Ultraviolet Explorer, the Hubble Space Telescope, or the Hopkins Ultraviolet Telescope. In the optical the lines are weaker, but the [O II] λλ3726,3729, [O III] λλ4959,5007, [N II] λλ6567,6584, [Ne II] λλ3918,3969, [S II] λ6720, and [S III] λ9320 lines should be detected with moderate exposures if the warm absorber is near the lower limit of the allowed temperature range, T <~ 1.5 x 10^5^ K. In this limit the Hα and [S III] λ3720 lines will require longer exposure times, but should be detectable as well.