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Session 78 - Unique Objects and Gamma Bursts.
Oral session, Thursday, June 13
Using a sequence of Hubble Space Telescope images (1990-1995),we have measured the astrometric (plane-of-the-sky) expansion of the dust cloud (the homunculus) surrounding the super-luminous, eruptive star eta Carinae. The measured expansion rate is 0.66date is in excellent agreement with the 1843 peak in the star's ``Great Eruption of 1838-1860.'' Doppler velocities for the expanding gas cloud were obtained from the ground-based spectra of Hillier and Allen [1992, 1993] for each point in the gas cloud. We combine the Doppler velocities with the astrometric velocities to create a new model (the hourglass) for the shape of the expanding gas cloud. Three tests are employed to compare our new model to two recently published models (the double-sphere and bipolar-caps). Only the hourglass model is consistent with all the available data.
Program listing for Thursday