A Search for UV Circumstellar Absorption in Fomalhaut, a New Beta Pic-like System

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Session 62 -- Very Young Stars
Display presentation, Thursday, 9:20-4:00, Pauley Room

[62.10] A Search for UV Circumstellar Absorption in Fomalhaut, a New Beta Pic-like System

F. Bruhweiler (CUA), K.-P. Cheng (NAS/NRC), Y. Kondo (NASA/GSFC)

Archival high dispersion IUE spectra have been used to search for UV circumstellar absorption features in the protoplanetary system candidate, $\alpha$ PsA (Fomalhaut). Recent sub-mm mapping of the region about $\alpha$ PsA has indicated a spatially resolved dust disk like that around $\beta Pic$. To determine how closely this object resembles $\beta$ Pic, we examined the available IUE data. Previous results by Bruhweiler \& Kondo (1981) revealed what was identified as interstellar C~I toward this nearby (7~pc) object. Examination of summed spectra with both the Short Wave and Long Wave Prime (SWP \& LWP) cameras finds no convincing evidence for circumstellar absorption from the species C~I, S~I, Mg~I, Mg~II, Fe~II, Fe~III, or Al~III. Based upon results from infrared and mm wavelengths specifying the aspect for the disk, the IUE observations suggest that, if a gas disk is present, it is thin with a limited scale-height. If the collisionally ionized non-photospheric Al~III seen in $\beta$ Pic is formed close to the stellar surface, the absence of this species in the UV spectrum of Fomalhaut could imply that, in contrast with $\beta$ Pic, no active gaseous disk infall onto the central star is now occurring.

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