AAS 197, January 2001
Session 8. Circumstellar Matter and Winds
Display, Monday, January 8, 2001, 9:30am-7:00pm, Exhibit Hall

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[8.23] \emph{FUSE} and \emph{HST}/STIS Observations of the AB Aurigae System

A. Roberge, P. D. Feldman (JHU), A. Lecavelier des Etangs, A. Vidal-Madjar, R. Ferlet (IAP), C. A. Grady (NOAO, GSFC), M. Deleuil (LAM), B. Woodgate (GSFC), F. C. Bruhweiler, A. Boggess (Catholic Univ.), FUSE Science Team

We present the first observations of a Herbig Ae star with a circumstellar disk made by the \emph{Far Ultraviolet Spectroscopic Explorer} (\emph{FUSE}), as well as a simultaneous observation of the star obtained with the \emph{Hubble Space Telescope} Space Telescope Imaging Spectrograph (STIS). The spectra of AB Aurigae show emission and absorption features arising from gasses that have a wide range in temperature, from hot \ion{O}{6} emission to cold H2 and CO absorption. Emissions from the highly ionized species \ion{O}{6} and \ion{C}{3} present in the \emph{FUSE} spectrum are redshifted, while absorption features arising from low-ionization species like \ion{O}{1}, \ion{N}{1}, and \ion{Si}{2} are blueshifted and show characteristic stellar wind line-profiles. We derive the total column density of H2 toward AB Aur and the gas kinetic temperature from absorption lines in the \emph{FUSE} spectrum. From the STIS spectrum, we derive the column densities of CO and \ion{H}{1}, allowing us to calculate the CO/H2 ratio, the total column density of hydrogen atoms, N\rm{H}, the fractional abundance of H2, and the gas-to-dust ratio, N\rm{H}/\rm{E(B-V)}. Nakajima & Golimowski (1995) suggested that the arc of reflection nebulosity seen to the east of AB Aur is the remnant of the original molecular cloud that collapsed to form the star. Our results suggest that the cold molecular gasses we observe toward AB Aur are located in this remnant molecular cloud envelope.

Based on observations made with the NASA-CNES-CSA \emph{Far Ultraviolet Spectroscopic Explorer}. \emph{FUSE} is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985. Also based on observations with the NASA-ESA \emph{Hubble Space Telescope} obtained at the STScI, which is operated by AURA, Inc. under NASA contract NAS5-26555.

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