1ST RESULTS FROM THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - RESOLVED VELOCITY AND DENSITY STRUCTURE IN THE BETA-PICTORIS CIRCUMSTELLAR GAS

We present the first HST Goddard High-Resolution Spectrograph (GHRS) observations of circumstellar (CS) gas around beta-Pictoris, providing the first evidence for resolved velocity and density structure in the CS gas. Two low-density features are visible in both observations. Comparison with IUE spectra suggests that at least one component may vary on time scales longer than the 23 day interval between the HST observations, implying that some of the low-density gas is CS. The high-density, infalling gas shows considerable velocity structure which varied dramatically between the two HST observations. The HST and IUE data are consistent with 2-3 infalling clumps of material per week. We infer an infall rate of 100-150 events yr-1, a rate which is broadly consistent with, but higher than, previously inferred infall rates. Collectively the GHRS data imply the presence of a more complex and dynamically active gaseous envelope than previously anticipated.