MASS OUTFLOW IN THE NEARBY PROTO PLANETARY SYSTEM, BETA-PICTORIS

Previous spectral studies of circumstellar dust around the nearby, candidate proto-planetary system, beta-Pictoris, have detected only infalling gas. The lack of detectable mass outflow has been critical in the interpretation of the origin of the circumstellar gas and in our understanding of the evolutionary status of the beta-Pictoris system. We present International Ultraviolet Explorer (IUE) high-dispersion spectra which show, in addition to infall, the presence of mass outflow, with a maximum observed outflow velocity of -60 km s-1, and a corresponding instantaneous outflow rate of 1.1 x 10(-14) M. yr-1, or 1.1 x 10(-11) M(Jupiter) yr-1. This mass outflow rate and terminal velocity are comparable to the magnitudes of mass infall rates and terminal velocities observed from late 1986 through early 1988. The implications of these observations on our understanding of the mechanisms producing infall from the surrounding circumstellar disk are discussed, as are the implications for our understanding of the evolutionary status of the beta-Pic system.