High-contrast observations of (136108) Haumea

Abstract

Context. The trans-Neptunian region of the Solar System is populated by a wide variety of icy bodies showing great diversity in orbital behavior, size, surface color, and composition. One can also see there are dynamical families and binary systems. One surprising feature detected in the spectra of some of the largest trans-Neptunians is the presence of crystalline water-ice. This is the case for the large TNO (136 108) Haumea (2003 EL 61 ). Aims. We seek to constrain the state of the water ice of Haumea and its satellites and to investigate possible energy sources that maintain the water ice in its crystalline form. Methods. Spectro-imaging observations in the near infrared were performed with the integral field spectrograph SINFONI mounted on UT4 at the ESO Very Large Telescope. The spectra of both Haumea and its larger satellite Hi'iaka were analyzed. Relative astrometry of the components was also measured, providing a check of the orbital solutions and equinox seasons. Results. We describe the physical characteristics of the crystalline water-ice present on the surface of Haumea and its largest satellite Hi'iaka and analyze possible sources of heating to maintain water in a crystalline state: tidal dissipation in the system components vs. radiogenic source. The surface of Hi'iaka appears to be covered by large grains of water ice, almost entirely in its crystalline form. Under some restricted conditions, both radiogenic heating and tidal forces between Haumea and Hi'iaka could provide the energy needed to maintain the ice in its crystalline state.

An icy Kuiper belt around the young solar-type star HD 181327

“…This implies that ice needs to be stored (and possibly produced) in the interior of the object before being brought to the surface, possibly through cryovolcanic events. The nature of water ice in KBOs remains unclear, but the vast majority of these objects are too small to experience such geological processes (Dumas et al 2011, and references therein). Thus KBOs covered by crystalline ice can only constitute particular examples, and the water ice covering the collisionally produced dust in the solar system is more likely amorphous.…”

The Size and Shape of the Oblong Dwarf Planet Haumea

“…Its rapid rotation rate, multiple satellites, and dynamically-related family members all suggest an early giant impact ). Its surface spectrum reveals a nearly pure water ice surface Trujillo et al 2007;Merlin et al 2007;Dumas et al 2011), with constraints on other organic compounds with upper bounds < 8% (Pinilla-Alonso et al 2009). Lacerda et al (2008) also find evidence for a dark spot on one side of the rotating body, make the surface albedo -3 -non-uniform.…”

Characterisation of candidate members of (136108) Haumea’s family

“…is surprisingly small (Schlichting & Sari 2009;Leinhardt et al 2010); 5. its surface composition is dominated by water ice (Tegler et al 2007;Trujillo et al 2007;Merlin et al 2007;Pinilla-Alonso et al 2009;Dumas et al 2011), yet it has a high density of 2.5-3.3 g cm −3 ); 6. it surface has a hemispherical colour heterogeneity, with a dark red "spot" on one side (Lacerda et al 2008;Lacerda 2009). Brown et al (2007) proposed that Haumea suffered a giant collision that ejected a large fraction of its ice mantle, which formed both the two satellites and the dynamical family and left Haumea with rapid rotation.…”