Near-infrared spectroscopy of Charon: Possible evidence for cryovolcanism on kuiper belt objects

Jason C. Cook, Steven J. Desch, Ted L. Roush, Chadwick A. Trujillo, T. R. Geballe

Research output: Contribution to journalArticlepeer-review

120 Scopus citations


We present the first reported adaptive optics spectra of Charon in the H and K bands, which examine the anti-Pluto and sub-Pluto hemispheres. The ice temperature is estimated at 40-50 K, based on the 1.65 μm feature of crystalline water ice. We obtain the most accurate profiles of the 2.21 μm feature and confirm that the feature is due to hydrated ammonia. We attribute hemispheric differences in the feature's profile to different hydration states. We calculate the rate at which crystalline water ice is amorphized by solar UV/visible radiation, finding that at the depths probed by H and K observations (≈350 μm), the e-folding time to amorphize ice is (3-5) × 10 4 yr. This implies Charon's ice crystallized from a melt, or has been heated to ≳90 K, during the last ∼ 105 yr. The extent of the crystalline water ice and the short timescales involved argue that surface renewal is necessary, a conclusion reinforced by the presence of ammonia hydrates. We investigate possible mechanisms for surface renewal and conclude that cryovolcanism is the most likely.

Original languageEnglish (US)
Pages (from-to)1406-1419
Number of pages14
JournalAstrophysical Journal
Issue number2 I
StatePublished - Jul 10 2007
Externally publishedYes


  • Comets: general
  • Infrared: general
  • Kuiper belt
  • Planets and satellites: individual (Charon)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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