AAS 207th Meeting, 8-12 January 2006
Session 120 Intergalactic Medium and Absorption Line Systems
Poster, Wednesday, 9:20am-6:30pm, January 11, 2006, Exhibit Hall

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[120.08] The Physical Conditions of "CIII-Only" Absorption Line Systems

B. C. Lacki, J. C. Charlton (Penn State University)

We examined the archives of the Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope (HST) / Space Telescope Imaging Spectrograph (STIS) to locate interesting quasar absorption line systems. Four "CIII-only" systems at z < 0.2 were noted, confirmed by Lyman alpha absorption. The column densities log N(C III) for these systems are in the range 13.5-14.0, but no other metal lines, such as CIV and OVI, are detected. We considered whether photoionization or collisional ionization could produce the observed systems. We discovered that both could produce the observed spectra, and derived ranges of ionization parameters, metallicities for each process. For photoionization, we found that the "CIII-only" systems could be produced when the ionization parameter, log U, is around -1.5, assuming a solar abundance pattern. We compare our results to the properties and rate of incidence of other types of absorption systems, such as CIV and OVI absorbers.

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