Circumstellar Gas Around Proto-Planetary System Candidates
Session 35 -- ISM: Abundances and Dust
Display presentation, Wednesday, June 14, 1995, 9:20am - 6:30pm

[35.13] Circumstellar Gas Around Proto-Planetary System Candidates

K.-P. Cheng (California State U./Fullerton), J.E. Neff (Penn State U.), F.C. Bruhweiler (Catholic U.)

We are studying the circumstellar (CS) gas around stars that are similar to $\beta$~Pictoris (A5 V), the well-known proto-planetary system candidate. This is the ultimate stage of our multiwavelength (IR+Optical+UV) search for possible planetary systems in all the A stars within 25 pc. Based on our ground-based Ca~II and Na~I spectra of the complete volume-limited sample of 62 A stars, we have identified at least 12 stars with possible CS gas. Since the fine-structure lines of the resonance UV1 multiplet of Fe~II near 2600~\AA\ are excellent diagnostics of CS gas, we are using the IUE high-dispersion archival data of our program stars to distinguish between circumstellar and interstellar lines. We also are searching for dynamic spectral features similar to the mass flows seen in spectra of $\beta$~Pic. Finally, we are combining our visual and ultraviolet (IUE) CS gas study with our previous IRAS CS dust survey to probe the link between CS gas envelopes and dust disks. Our goal is to ascertain if these $\beta$~Pic-like stars, as a group, represent some phase of planet formation.