摘要：Context. The transneptunian 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.
Aims. The dwarf planet (136108) Haumea is among the largest
transneptunian objects (TNOs) and is a very fast rotator (~3.9 h). This dwarf planet displays a
highly elongated shape and hosts two small moons that are covered with crystalline water
ice, similar to their central body. A particular region of interest is the Dark Red Spot
(DRS) identified on the surface of Haumea from multiband light-curve analysis (Lacerda et
al. 2008). Haumea is also known to be the largest member of the sole TNO family known to
date, and an outcome of a catastrophic collision that is likely responsible for the unique
characteristics of Haumea.
Methods. We report here on the analysis of a new set of near-infrared
Laser Guide Star assisted observations of Haumea obtained with the Integral Field Unit
(IFU) Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) at the
European Southern Observatory (ESO) Very Large Telescope (VLT) Observatory. Combined with
previous data published by Dumas et al. (2011), and using light-curve measurements in the
optical and far infrared to associate each spectrum with its corresponding rotational
phase, we were able to carry out a rotationally resolved spectroscopic study of the
surface of Haumea.
Results. We describe the physical characteristics of the crystalline
water ice present on the surface of Haumea for both regions, in and out of the DRS, and
analyze the differences obtained for each individual spectrum. The presence of crystalline
water ice is confirmed over more than half of the surface of Haumea. Our measurements of
the average spectral slope (1.45 ±
0.82% by 100 nm) confirm the redder characteristic of the spot region.
Detailed analysis of the crystalline water-ice absorption bands do not show significant
differences between the DRS and the remaining part of the surface. We also present the
results of applying Hapke modeling to our data set. The best spectral fit is obtained with
a mixture of crystalline water ice (grain sizes smaller than 60 μm) with a few percent of
amorphous carbon. Improvements to the fit are obtained by adding ~10% of amorphous water ice.
Additionally, we used the IFU-reconstructed images to measure the relative astrometric
position of the largest satellite Hi‘iaka and determine its orbital elements. An orbital
solution was computed with our genetic-based algorithm GENOID and our results are in full
agreement with recent results.
关键词：Kuiper belt objects: individual: (136108) Haumea;planets and satellites: surfaces;techniques: imaging spectroscopy;techniques: high angular resolution
