Polarimetry of the dwarf planet (136199) Eris^*

¹ Astronomical Observatory of Kharkiv National University, 35 Sumska str., 61022 Kharkiv, Ukraine e-mail: irina@astron.kharkov.ua
² Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland, UK e-mail: sba@arm.ac.uk
³ Observatory, PO Box 14, 00014 University of Helsinki, Finland e-mail: muinonen@cc.helsinki.fi
⁴ LESIA, Observatoire de Paris, 5 place Jules Janssen, 92195 Meudon Cedex, France e-mail: [antonella.barucci;sonia.fornasier]@obspm.fr
⁵ INAF – Oss. Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy e-mail: tozzi@arcetri.astro.it
⁶ University of Paris 7 “Denis Diderot”, 10 rue Alice Domon et Leonie Duquet, 75013 Paris, France
⁷ University of Maryland, College Park, MD, USA e-mail: ludmilla@astro.umd.edu

Received: 7 July 2007
Accepted: 23 November 2007

Abstract

Context.We study the surface properties of the transneptunian population of Solar-system bodies.

Aims. We investigate the surface characteristics of the large dwarf planet (136199) Eris.

Methods. With the FORS1 instrument of the ESO Very Large Telescope, we have obtained Bessell broadband R linear polarimetry and broadband V and I photometry of Eris. We have modelled the observations in terms of the coherent-backscattering mechanism to constrain the surface properties of the object.

Results. Polarimetric observations of Eris show a small negative linear polarization without opposition surge in the phase angle range of . The photometric data allow us to assume a brightness opposition peak at phase angles below . The data obtained suggest a possible similarity to the polarimetric and photometric phase curves of Pluto. The measured absolute magnitude and broadband colors of Eris are H_V=-1.15 mag,  mag, and  mag.

Conclusions.The observational data with theoretical modelling are in agreement with the surface of Eris being covered by large inhomogeneous particles.