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A. Roberge, P.D. Feldman, J.B. McPhate, J.H. Debes (JHU), A.M. Lagrange (Groupe d'Astrophysique de Grenoble), A. Vidal-Madjar (IAP), A. Jolly (Obs. de Paris-Meudon)
Spectra of Beta Pictoris were obtained on Dec. 6, 1997 and Dec. 19, 1997, using the Echelle mode of the Space Telescope Imaging Spectrograph (STIS). These data cover the wavelength range from 1459 Å{} to 2888 Å{} and exhibit many circumstellar atomic absorption features, including CI and FeII. The CO A-X (0-0,1-0,2-0) bands were also observed, including the bands arising from 13CO. Preliminary analysis of the CO bands and of the CI 1561 Å{} and 1657 Å{} multiplets has been completed. Also analyzed were two lines arising from the metastable 1D state of the ground configuration of CI, at 1463 Å{} and 1931 Å. The CI features show the multiple velocity component structure previously observed in HST-GHRS spectra of Beta Pictoris (Jolly et al., A&A 329, 1028 (1998)) and attributed to dissociation of CO evaporating from cometary bodies orbiting the star at different velocities and locations. Velocities and turbulent Doppler widths obtained from the FeII lines were used to aid the modeling of the highly saturated CI multiplets. The CI features show significant variation between the two days of observation; the total column density of ground state C(3P) is approximately 3-5 x 1015 cm-2. The total column density of C(1D) is approximately 3-6 x 1013 cm-2.