[Previous] | [Session 131] | [Next]
J. Ding, C. W. Churchill, J. C. Charlton (Penn State University)
We used spectra from STIS/HST (R=30,000), together with those from HIRES/Keck (R=45,000), to study the three absorption systems at z=0.9254, 0.9276, and 0.9343 towards the quasar PG 1206+459. We will present a WIYN image of the quasar field obtained with ~0.7'' seeing and consider the issues of galaxy hosts for the absorbers. The chemical and ionization species covered by STIS spectra are Lya, NI, OI, SiII, CII, SII, SiIII, SiIV, CIV, and NV, while the MgI, MgII, and FeII profiles are provided by HIRES. The similar features shown in MgII and in other low ionization transitions, such as FeII and SiII, in the z=0.9254 and z=0.9276 systems require at least six components each. Though contaminated with Galactic FeII, the broad, blended Lya profiles in both z=0.9254 and z=0.9276 have a contribution from a separate phase with a larger internal motion. The excess of MgI/MgII indicates that instead of arising in the same phase as MgII, MgI could be produced in separate, narrow clouds with smaller internal motions. High ionization transitions, such as SiIV, CIV and NV, indicate that a separate higher ionization phase is present in each of the three systems. In the z=0.9254 system this phase has multiple components offset from the low ionization clouds. In the z=0.9276 system the high ionization gas produces a broad and blended feature.
This project is funded by the National Science Foundation and by NASA through the STScI and the LTSA program.