AAS 201st Meeting, January, 2003
Session 49. Eta Carinae, LBVs, and Circumstellar Disks
Poster, Tuesday, January 7, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[49.14] Probing the circumstellar environment of the Herbig Be star HD 100546 with FUSE.

M. Deleuil (LAM), A. Lecavelier des Etangs (IAP), J.-C. Bouret (LAM), A. Roberge (DTM), A. Vidal-Madjar (IAP), P.D. Feldman (JHU), R. Ferlet (IAP), C. Martin (LAM)

We present an analysis of Far Ultraviolet Spectroscopic Explorer (FUSE) spectra probing the gaseous circumstellar environment of the Herbig Be star HD 100546. Numerous narrow absorption lines of circumstellar origin are observed from molecular and atomic gas, neutral and weakly ionized. At short wavelengths where the stellar flux is undetected, strong and broad emission lines due to highly ionised species such as C III and O VI are present. These lines formed in a dense and hot gas, collisionally heated, probe a region which extends over a few stellar radii above the star's surface.

Comparison of two spectra recorded two years apart, reveal strong variations not limited to the atomic circumstellar lines as previously reported but which also affect the photospheric flux itself as well as the emission lines at short wavelengths. Our results highlight a complex circumstellar environment with evidences of a high temperature emission gas related to a chromospheric complex close to the stellar surface, sporadic wind and accretion phenomena which affect mainly volatile species like N I and O I(1D).

Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.

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