Surface composition and temperature of the TNO Orcus (original) (raw)

A&A 479, L13-L16 (2008)

Letter to the Editor

1, F. Merlin1, A. Guilbert1, C. de Bergh1, A. Alvarez-Candal1, O. Hainaut2, A. Doressoundiram1, C. Dumas2, T. Owen3 and A. Coradini4

1 LESIA, Observatoire de Paris, 92195 Meudon Principal Cedex, France e-mail: antonella.barucci@obspm.fr
2 ESO, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
3 Institute or Astronomy, 2680 Woodlawn Drive, Honolulu, HI96822, USA
4 INAF – IFSI, Via del Fosso del Cavaliere, 00133 Roma, Italy

Received: 16 November 2007
Accepted: 19 December 2007

Abstract

_Aims._The aim of this paper is to investigate the surface composition of the Transneptunian Object (TNO) Orcus.

_Methods._High quality observations have been carried out with the new instrument SINFONI at the Very Large Telescope (VLT) of ESO.

_Results._Crystalline water ice, and possibly ammonia ice, have been found from spectroscopic observations of the TNO Orcus between 1.4 and 2.4 _μ_m.

_Conclusions._The existence of such ices on the surface of Orcus may indicate a renewal mechanism on the surface and geological activity. The presence of ammonia on the surface of Orcus, if confirmed, could have important implications for the composition of the primitive solar nebula and the formation of the TNO population.

Key words: Kuiper Belt / techniques: spectroscopic / methods: observational

Based on observations performed at the European Southern Observatory (ESO), proposal 178.C-0867.