CIARNIELLO, MauroMauroCIARNIELLODE SANCTIS, MARIA CRISTINAMARIA CRISTINADE SANCTISAmmannito, E.E.AmmannitoRAPONI, AndreaAndreaRAPONILONGOBARDO, ANDREAANDREALONGOBARDOPALOMBA, ErnestoErnestoPALOMBACARROZZO, FILIPPO GIACOMOFILIPPO GIACOMOCARROZZOTOSI, FedericoFedericoTOSILi, J. -Y.J. -Y.LiSchröder, S. E.S. E.SchröderZAMBON, FrancescaFrancescaZAMBONFRIGERI, ALESSANDROALESSANDROFRIGERIFONTE, SERGIOSERGIOFONTEGiardino, M.M.GiardinoPieters, C. M.C. M.PietersRaymond, C. A.C. A.RaymondRussell, C. T.C. T.Russell2020-09-072020-09-0720170004-6361http://hdl.handle.net/20.500.12386/27182Aims: We present a study of the spectrophotometric properties of dwarf planet Ceres in the visual-to-infrared (VIS-IR) spectral range by means of hyper-spectral images acquired by the VIR imaging spectrometer on board the NASA Dawn mission. Methods: Disk-resolved observations with a phase angle within the 7° <α < 132° interval were used to characterize Ceres' phase curve in the 0.465-4.05 μm spectral range. Hapke's model was applied to perform the photometric correction of the dataset to standard observation geometry at VIS-IR wavelength, allowing us to produce albedo and color maps of the surface. The V-band magnitude phase function of Ceres has been computed from disk-resolved images and fitted with both the classical linear model and H-G formalism. Results: The single-scattering albedo and the asymmetry parameter at 0.55 μm are w = 0.14 ± 0.02 and ξ = -0.11 ± 0.08, respectively (two-lobe Henyey-Greenstein phase function); at the same wavelength, Ceres' geometric albedo as derived from our modeling is 0.094 ± 0.007; the roughness parameter is θ=29° ± 6°. Albedo maps indicate small variability on a global scale with an average reflectance at standard geometry of 0.034 ± 0.003. Nonetheless, isolated areas such as the Occator bright spots, Haulani, and Oxo show an albedo much higher than average. We measure a significant spectral phase reddening, and the average spectral slope of Ceres' surface after photometric correction is 1.1% kÅ^-1 and 0.85% kÅ^-1 at VIS and IR wavelengths, respectively. Broadband color indices are V-R = 0.38 ± 0.01 and R-I = 0.33 ± 0.02. Color maps show that the brightest features typically exhibit smaller slopes. The H-G modeling of the V-band magnitude phase curve for α < 30° gives H = 3.14 ± 0.04 and G = 0.10 ± 0.04, while the classical linear model provides V(1,1,0°) = 3.48 ± 0.03 and β = 0.036 ± 0.002. The comparison of our results with spectrophotometric properties of other minor bodies indicates that Ceres has a less back-scattering phase function and a slightly higher albedo than comets and C-type objects. However, the latter represents the closest match in the usual asteroid taxonomy.STAMPAenArticle10.1051/0004-6361/2016294902-s2.0-85013040729000394465000129https://www.aanda.org/articles/aa/full_html/2017/02/aa29490-16/aa29490-16.html2017A&A...598A.130CFIS/05 - ASTRONOMIA E ASTROFISICA