Letter to the Editor

Is Sedna another Triton?

¹ LESIA, Observatoire de Paris, 92195 Meudon Principal Cedex, France e-mail: [antonella.barucci;frederic.merlin;catherine.debergh]@obspm.fr
² NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA e-mail: Dale.P.Cruikshank@nasa.gov
³ INAF-OAR Via Frascati 33, 00040 Monteporzio Catone (Roma), Italy e-mail: dotto@mporzio.astro.it
⁴ IAS, Université Paris-Sud, 91405 Orsay Cedex, France e-mail: francois.poulet@ias.u-psud.fr
⁵ SETI Institute, Mountain View, CA & NASA Ames Research Center, USA e-mail: cdalleore@mail.arc.nasa.gov
⁶ Dipartimento di Astronomia, Vicolo dell'Osservatorio 2, 35122 Padova, Italy e-mail: fornasier@pd.astro.it

Received: 30 May 2005
Accepted: 20 June 2005

Abstract

90377 Sedna is, so far, the largest and most distant trans-neptunian object. It was observed at visible and near-infrared wavelengths using simultaneously two 8.2 m telescopes at the Very Large Telescope of the European Southern Observatory. The spectrum of Sedna suggests the presence on its surface of different ices (total abundance >50%). Its surface composition is different from that determined for other trans-neptunian objects, and apparently resembles that of Triton, particularly in terms of the possible presence of nitrogen and methane ices.