Physical Properties of Gas Disks around Shell Stars with and Without Dust

摘要

Analysis of archival IRAS and IUE data has resulted in: (1) identification of 8new A star proto-planetary candidates; (2) detection of a mass outflow event around Beta Pic (subsequently confirmed by the 1991 July HST observation); and (3) confirmation of the suggestion by Waters et al. (1988) that 51 Oph is a protoplanetary system similar to beta Pic with the detection of high density, high velocity, collisionally ionized accreting gas in the line of sight toward this star.