Near-infrared spectroscopy of Miranda

¹ Observatoire de Paris-Meudon / LESIA, 92190 Meudon, France
e-mail: florian.gourgeot@obspm.fr
² European Southern Observatory, Alonso de Córdova 3107, 1900 Casilla Vitacura, Santiago, Chile
³ Université Denis Diderot, Paris VII, 75013 Paris, France
⁴ Observatoire Astronomique Marseille-Provence, 13013 Marseille, France
⁵ Instituto de Astrofísica de Andalucía – CSIC, Glorieta de la Astronomía S/N, 18008 Granada, Spain
⁶ Observatório Nacional, COAA, Rua General José Cristino 77, 20921-400 Rio de Janeiro, Brazil

Received: 29 May 2013
Accepted: 16 October 2013

Abstract

Aims. We present new near-infrared spectra of the leading and trailing hemispheres of Uranus’s icy satellite Miranda. This body is probably the most remarkable of all the satellites of Uranus, because it displays series of surface features such as faults, craters, and large-scale upwelling, a remnant of a geologically very active past.

Methods. The observations were obtained with PHARO at Palomar and SpeX at the IRTF Observatory. We performed spectral modelings to further constrain the nature and the chemical and physical states of the compounds possibly present on the surface of Miranda.

Results. Water ice signatures are clearly visible in the H and K bands, and it appears to be found in its crystalline state over most of the satellite’s surface. Unlike what has been found for Uranus’s outer moons, we did not find any significative differences in the abundances of ices covering the leading and trailing hemispheres of Miranda. The signature of carbon dioxide cannot be seen in our spectra, which could still account for the presence of ammonia hydrate, though in small amounts.