Search For Proto-Planetary System Candidates
Session 9 -- Solar System
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

## [9.01] Search For Proto-Planetary System Candidates

James E. Neff (Penn State), Kwang-Ping Cheng, Fred Bruhweiler (Catholic U.)

We report on our continuing search for circumstellar gas in a volume limited sample of 62 nearby A stars. Since the evolutionary lifetimes of A stars ($\le 10^9$ yrs) roughly correspond to the era of planet formation and subsequent heavy bombardment" in our solar system, our study could provide valuable insight into the origin of our own Solar System. From high-resolution visual (NSO McMath--Pierce) and ultraviolet (IUE) spectroscopy, we have already identified several stars with circumstellar gas. We present the results of the ground-based, northern-hemisphere component of our survey. We have obtained high-resolution ($\lambda/\Delta\lambda\sim$120,000) spectra of the Ca~II~K and Na~I~D lines from each of our program stars. We are combining these results with our previous IRAS survey (Cheng et al. 1992, Ap.J., 396, L83), to probe the link between stars with circumstellar gas and those showing circumstellar dust. Our aim is not just to identify stars with gas, or stars with gas and dust, but to identify systems with dynamic spectral activity similar to $\beta$ Pic. By studying the gas dynamics in the disks of other stars like $\beta$ Pic with instruments such as Goddard High Resolution Spectrograph (GHRS), we can obtain fundamental clues to the physics of accretion disks of young evolving systems.