title: Detection of water ice on Nereid.
abstract: We report the detection of the 1.5 and 2.0 micrometers absorption bands of water ice in the near-infrared reflection spectrum of Neptune's distant irregular satellite Nereid. The spectrum and albedo of Nereid appear intermediate between those of the Uranian satellites Umbriel and Oberon, suggesting a surface composed of a combination of water ice frost and a dark and spectrally neutral material. In contrast, the surface of Nereid appears dissimilar to those of the outer solar system minor planets Chiron, Pholus, and 1997 CU26. The spectrum thus provides support for the hypothesis that Nereid is a regular satellite formed in a circumplanetary environment rather than a captured object.
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Brown
authors.forename: C D
authors.initials: CD
authors.lastname: Koresko
authors.forename: G A
authors.initials: GA
authors.lastname: Blake
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D005118:Extraterrestrial Environment; D007053:Ice; D018543:Minor Planets; D018541:Neptune; D019265:Spectroscopy, Near-Infrared; D018540:Uranus; D014867:Water
chemical_list: D007053:Ice; D014867:Water