Detection of accreting circumstellar gas around weak emission-line Herbig Ae/Be stars |
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Authors: | C A Grady M R Pérez P S Thé |
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Institution: | (1) Applied Research Corporation, Landover Maryland, USA;(2) Science Programs, Computer Sciences Corporation and IUE Observatory, Greenbelt, Maryland, USA;(3) Astronomical Institute Anton Pannekoek,, University of Amsterdam, Amsterdam, The Netherlands;(4) Guest Observer, IUE Observatory, NASA/GSFC, USA |
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Abstract: | 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 Teff, and column densities intermediate between those observed toward classical Herbig Ae/Be stars and the nearby proto-planetary system 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 h 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.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A. |
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