Photometry of the nucleus of Comet 9P/Tempel 1 from Stardust-NExT flyby and the implications

The photometric properties of the nucleus of Comet 9P/Tempel 1 as modeled from the Stardust-NExT images agree with those reported by Li et al. (Li, J.-Y. et al. [2007a]. Icarus 187, 41–55; Li, J.-Y., A’Hearn, M.F., McFadden, L.A., Belton, M.J.S. [2007b]. Icarus 188, 195–211) from Deep Impact images. No significant changes are detectable by comparing the two image-sets taken one comet year apart. The overall photometric variations on the ∼70% of the surface of Tempel 1 observed by Deep Impact and Stardust-NExT are small, with albedo variations of ±10% full-width-at-half-maximum and non-detectable variations in phase function and surface roughness. Some bright surface albedo features visible in the outbound images have an albedo about 25% higher than that of surrounding area. No bright albedo features similar to those ice patches reported by Sunshine et al. (Sunshine, J.M., et al. [2006]. Science 311, 1453–1455) are seen on the outbound side, which was not imaged by DI. The similar global photometric properties among cometary nuclei may indicate that these properties are dominated by cometary activity that results in constant resurfacing on comets. Tiny amounts of ice concentration on their surface can significantly change the local photometric properties.