• Dotto, Elisabetta
• Merlin, F.
• Barucci, Maria A.
• Doressoundiram, A.
• De Bergh, C.

Abstract

The Plutino 55638 was observed with visible and near-infrared spectroscopy using two 8.2 m telescopes at VLT of the European Southern Observatory (Cerro Paranal, Chile). The visible spectrum is featureless with a slope between 400 and 850 nm of 27.9±0.1%/100 nm. In the near-infrared, the spectrum is featureless in J and shows clear bands in the H and K regions, around 2.0 µm and 2.27 µm. We attributed the 2.0 µm band to H<SUB>2</SUB>O ice while the feature at 2.27 µm to the presence of CH<SUB>3</SUB>OH ice (and/or a photolytic product of methanol having small molecular weight). To investigate the possible composition of the surface of this object, radiative transfer models, based on the Hapke (1981 and 1993) and Shkuratov (1999) theories, have been computed considering geographical and intimate mixtures of different materials. Assuming an albedo of about 0.10 at 0.55 µm, the intimate mixture gives the best match over the spectral range between 0.4 and 2.4 µm and it is composed of amorphous H<SUB>2</SUB>O ice (30µm), CH<SUB>3</SUB>OH ice (40µm), Titan tholin and Triton tholin with particles of 4µm size, and amorphous carbon (10µm). Some olivine needs to be added with the Shkuratov intimate model. The amount of each compound slightly depends of the used model. The behavior of the spectrum of (55638) 2002 VE<SUB>95</SUB> is very similar to that of the very red Centaur Pholus (Cruikshank et al., 1998) and this similarity could imply a common origin. The confirmation of the presence of methanol on the surface of this TNO and the Centaur Pholus is very important and would indicate the chemically primitive nature of these bodies....

Topics

• impedance spectroscopy
• surface
• compound
• amorphous
• Carbon
• molecular weight
• infrared spectroscopy
• Near-infrared spectroscopy