Examinando por Autor "Feller, C."

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Acceso Abierto
Multidisciplinary analysis of the Hapi region located on Comet 67P/Churyumov–Gerasimenko
(Oxford Academics: Oxford University Press, 2019-05-07) Pajola, M.; Lee, J. C.; Oklay, N.; Hviid, S. F.; Penasa, L.; Mottola, S.; Shi, X.; Fornasier, S.; Davidsson, B. J. R.; Giacomini, L.; Lucchetti, A.; Massironi, M.; Vicent, J. B.; Bertini, I.; Naletto, G.; Ip, W. H.; Sierks, H.; Lamy, Philippe; Rodrigo, Rafael; Koschny, D.; Keller, H. U.; Agarwal, J.; Barucci, M. A.; Bertaux, J. L.; Bodewits, D.; Cambianica, P.; Cremonese, G.; Da Deppo, V.; Debei, S.; De Cecco, M.; Deller, J.; El Maarry, M. R.; Feller, C.; Ferrari, S.; Fulle, M.; Gutiérrez, Pedro J.; Güttler, C.; Lara, L. M.; La Forgia, F.; Lazzarin, M.; Lin, Z. Y.; López Moreno, J. J.; Marzari, F.; Preusker, F.; Scholten, F.; Toth, I.; Tubiana, C.; European Space Agency (ESA); Pajola, M. [0000-0002-3144-1277]; Penasa, L. [0000-0002-6394-3108]; Fornasier, S. [0000-0001-7678-3310]; Lucchetti, A. [0000-0001-7413-3058]; Vicent, J. B. [0000-0001-6575-3079]; Naletto, G. [0000-0003-2007-3138]; Barucci, M. A. [0000-0002-1345-0890]; Bertaux, J. L. [0000-0003-0333-229X]; Deller, J. [0000-0001-8341-007X]; Fulle, M. [0000-0001-8435-5287]; Güttler, C. [0000-0003-4277-1738]; Tubiana, C. [0000-0001-8475-9898]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
By using the Rosetta/OSIRIS-NAC data set taken in 2014 August, we focus on the neck region, called Hapi, located on 67P Churyumov–Gerasimenko’s Northern hemisphere. The gravitational potential and slopes of Hapi, coupled with the geological unit identification and the boulder size–frequency distributions, support the interpretation that both taluses and gravitational accumulation deposits observable on Hapi are the result of multiple cliff collapses that occurred at different times. By contrast, the fine-particle deposits observable in the central part of the study area are made of aggregates coming from the Southern hemisphere and deposited during each perihelion passage. Both the consolidated terrains on the western part of Hapi, as well as the centrally aligned ridge made of boulder-like features, suggest that Hapi is in structural continuity with the onion-like structure of the main lobe of 67P. Despite the dusty blanket observable on Hapi, its terrains are characterized by water-ice-rich components that, once repeatedly and rapidly illuminated, sublimate, hence resulting in the strong jet activity observed in 2014 August.
Acceso Abierto
Rosetta/OSIRIS observations of the 67P nucleus during the April 2016 flyby: high-resolution spectrophotometry
(EDP Sciences, 2019-09-20) Feller, C.; Fornasier, S.; Ferrari, S.; Hasselmann, P. H.; Barucci, M. A.; Massironi, M.; Deshapriya, J. D. P.; Sierks, H.; Naletto, G.; Lamy, Philippe; Rodrigo, Rafael; Koschny, D.; Davidsson, Björn J. R.; Bertaux, J. L.; Bertini, I.; Bodewits, D.; Cremonese, G.; Da Deppo, V.; Debei, S.; De Cecco, M.; Fulle, M.; Gutiérrez, Pedro J.; Güttler, C.; Ip, W. H.; Keller, H. U.; Lara, L. M.; Lazzarin, M.; López Moreno, J. J.; Marzari, F.; Shi, X.; Tubiana, C.; Gaskell, B.; La Forgia, F.; Lucchetti, A.; Mottola, S.; Pajola, M.; Preusker, F.; Scholten, F.; 0000-0002-2941-3875; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. From August 2014 to September 2016, the Rosetta spacecraft followed comet 67P/Churyumov–Gerasimenko along its orbit. After the comet passed perihelion, Rosetta performed a flyby manoeuvre over the Imhotep–Khepry transition in April 2016. The OSIRIS/Narrow-Angle-Camera (NAC) acquired 112 observations with mainly three broadband filters (centered at 480, 649, and 743 nm) at a resolution of up to 0.53 m/px and for phase angles between 0.095° and 62°. Aims. We have investigated the morphological and spectrophotometrical properties of this area using the OSIRIS/NAC high-resolution observations. Methods. We assembled the observations into coregistered color cubes. Using a 3D shape model, we produced the illumination conditions and georeference for each observation. We mapped the observations of the transition to investigate its geomorphology. Observations were photometrically corrected using the Lommel–Seeliger disk law. Spectrophotometric analyses were performed on the coregistered color cubes. These data were used to estimate the local phase reddening. Results. The Imhotep–Khepry transition hosts numerous and varied types of terrains and features. We observe an association between a feature’s nature, its reflectance, and its spectral slopes. Fine material deposits exhibit an average reflectance and spectral slope, while terrains with diamictons, consolidated material, degraded outcrops, or features such as somber boulders present a lower-than-average reflectance and higher-than-average spectral slope. Bright surfaces present here a spectral behavior consistent with terrains enriched in water-ice. We find a phase-reddening slope of 0.064 ± 0.001%/100 nm/° at 2.7 au outbound, similar to the one obtained at 2.3 au inbound during the February 2015 flyby. Conclusions. Identified as the source region of multiple jets and a host of water-ice material, the Imhotep–Khepry transition appeared in April 2016, close to the frost line, to further harbor several potential locations with exposed water-ice material among its numerous different morphological terrain units.