DETECTION OF ACCRETING CIRCUMSTELLAR GAS AROUND WEAK EMISSION-LINE HERBIG AE/BE STARS

We present archival and recent IUE high dispersion spectra of late B stars which reveal the presence of accreting gas with velocities as high as 350 km s-1, collisional ionization of the accreting gas to temperatures above the stellar T(eff), and column densities intermediate between those observed toward classical Herbig Ae/Be stars and the nearby proto-planetary system beta Pictoris. One of the stars, HD 176386, while lacking obvious optical signatures of youth, is a member of the R CrA star formation region, and with an inferred age of 2.8 Myr has not yet arrived on the zero-age main sequence (ZAMS). The other object, an isolated, field B star with pronounced IR excess due to warm, circumstellar dust, 51 Oph, exhibits only modest Halpha emission. The combination of high velocity, accreting gas in systems with IR excesses due to circumstellar dust suggests that not only are these objects candidate proto-planetary systems, but that they may represent an extension to higher stellar masses of the weak-emission pre-main sequence (PMS) stars.