The Discovery of Argon in Comet C/1995 O1 (Hale-Bopp)

  title={The Discovery of Argon in Comet C/1995 O1 (Hale-Bopp)},
  author={S. Alan Stern and David C. Slater and Michel C. Festou and Joel Wm. Parker and G.M.F. A’Hearn and Eric P. Wilkinson},
  journal={The Astrophysical Journal},
On 1997 March 30.14, we observed the EUV spectrum of the bright comet C/1995 O1 (Hale-Bopp) at the time of its perihelion, using our Extreme Ultraviolet Spectrograph sounding-rocket telescope/spectrometer. The spectra reveal the presence H Lyβ, O+, and, most notably, argon. Modeling of the retrieved Ar production rates indicates that comet Hale-Bopp is enriched in Ar relative to cosmogonic expectations. This in turn indicates that Hale-Bopp's deep interior has never been exposed to the 35-40 K… 
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