Nicmos/hst Post-perihelion Images of Comet Hale–bopp in Outburst

Near-infrared images of comet Hale–Bopp (C/1995 O1) were obtained from NICMOS/HST on UT August 27–28, 1997, when the comet emerged from the 50 degree solar elongation limit at 2.99 AU from Earth. Diffraction-limited images were obtained with camera 2 filters centered at 1.87, 1.90, 2.04 and 2.22 μm with ∼0.2′′ resolution (0.076′′/pixel; 165 km/pixel). Over the 1.7hour baseline of observation, a recent (<7 hours) outburst is seen in the form of an expanding spiral arm with a projected expansion velocity of ∼80 m/s. Other asymmetric features include a jet emanating from the nucleus and several static linear features. Comparisons of the flux distribution in the 2.04 and 2.22 μm filters indicate that the region near the nucleus exhibits a slight,∼3%, water ice absorption.