A&A 422, L43-L46 (2004)
DOI: 10.1051/0004-6361:20048004

Letter

Water ice on the surface of the large TNO 2004 DW

S. Fornasier¹, E. Dotto², M. A. Barucci³ and C. Barbieri<sup>1

1</sup>  Astronomical Department of Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
    e-mail: [fornasier;barbieri]@pd.astro.it
²  INAF - Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone (Roma), Italy
    e-mail: dotto@mporzio.astro.it
³  LESIA, Observatoire de Paris, 92195 Meudon Pricipal Cedex, France
    e-mail: antonella.barucci@obspm.fr

(Received 14 May 2004 / Accepted 15 June 2004)

Abstract
We have obtained visible and near infrared spectra of the Trans Neptunian object 2004 DW, a few days after its discovery, at the Telescopio Nazionale Galileo (TNG). 2004 DW belongs to the plutino dynamical class and has an estimated diameter of about 1600 km, that makes it the largest known object, except Pluto, in the plutino and classical TNO populations. Our data clearly show the 1.5 and 2  m bands associated to water ice, while the visible spectrum is nearly neutral and featureless. To interpret the available data we modelled the surface composition of 2004 DW with two different mixtures of organics (Titan tholin and kerogen), amorphous carbon and water ice.

Key words: Kuiper Belt -- techniques: spectroscopic

© ESO 2004

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