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

Summary of Jian-Yang Li's paper

  Albedo Map
  This figure shows the albedo map of the nucleus of Tempel 1 derived from individual images. The numbers 300xx are image sequence numbers. The numbers in parentheses are solar phase angles. Overall the albedo variations of this nucleus is about 10% View larger image

The vast majority are shown to have been caused by cometary outbursts, another form of cryo-volcanic activity. This follows from the observed rate of occurrence of outbursts observed in the Deep Impact mission and Earth-based observations as compared to the large number of pits seen on the surface.

The photometric properties of Tempel 1's nucleus remain the same as derived from the Deep Impact data collected one apparition ago. This also suggests that the cameras onboard both Deep Impact and Stardust spacecraft are well calibrated, enabling direct comparisons of the photometric properties among the nuclei of Comets Tempel 1, Wild 2, and Hartley 2 as visited by both spacecraft. Overall the nucleus of Tempel 1 displays similar global photometric properties with the nuclei of Wild 2 and Hartley 2. The albedo variations of Tempel 1 is about 10%, similar to those of Wild 2 and Hartley 2, and comparable to those of most asteroids. The similar photometric properties among cometary nuclei may indicate that these properties are dominated by cometary activity that results in constant resurfacing on comets. Some areas visible during the outbound of NExT flyby have albedos about 25% higher than the global average.

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“When we see comets up in the sky they're really spectacular. But unless you get close to a comet, you can't really figure out what's going on.”

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