Examinando por Autor "Oklay, N."

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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
Seasonal variations in source regions of the dust jets on comet 67P/Churyumov-Gerasimenko
(EDP Sciences, 2019-09-20) Lai, I. L.; Ip, W. H.; Lee, J. C.; Lin, Z. Y.; Vicent, J. B.; Oklay, N.; Sierks, H.; Barbieri, C.; Lamy, Philippe; Rodrigo, Rafael; Koschny, D.; Rickman, H.; Keller, H. U.; Agarwal, J.; Barucci, M. A.; Bertaux, J. L.; Bertini, I.; Bodewits, D.; Boudreault, S.; Cremonese, G.; Da Deppo, V.; Davidsson, B. J. R.; Debei, S.; De Cecco, M.; Deller, J.; Fornasier, S.; Fulle, M.; Groussin, O.; Gutiérrez, Pedro J.; Güttler, C.; Hofmann, M.; Hviid, S. F.; Jorda, L.; Knollenberg, J.; Kovács, G.; kramm, J. R.; Kührt, E.; Küppers, M.; Lara, L. M.; Lazzarin, M.; López Moreno, J. J.; Marzari, F.; Naletto, G.; Shi, X.; Tubiana, C.; Thomas, N.; Ministry of Science and Technology, Taiwan (MOST)
Aims. We investigate the surface distribution of the source regions of dust jets on comet 67P/Churyumov-Gerasimenko as a function of time. Methods. The dust jet source regions were traced by the comprehensive imaging data set provided by the OSIRIS scientific camera. Results. We show in detail how the projected footpoints of the dust jets and hence the outgassing zone would move in consonance with the sunlit belt. Furthermore, a number of source regions characterized by repeated jet activity might be the result of local topographical variations or compositional heterogeneities. Conclusions. The spatial and temporal variations in source regions of the dust jets are influenced significantly by the seasonal effect. The strong dependence on the solar zenith angle and local time could be related to the gas sublimation process driven by solar insolation on a surface layer of low thermal inertia.
Acceso Abierto
The Rocky‐Like Behavior of Cometary Landslides on 67P/Churyumov‐Gerasimenko
(American Geophysical Union: Advancing Earth and Space Science, 2019-12-18) Lucchetti, A.; Penasa, L.; Pajola, M.; Massironi, M.; Teresa Brunetti, M.; Cremonese, G.; Oklay, N.; Vicent, J. B.; Mottola, S.; Fornasier, S.; Sierks, H.; Naletto, G.; Lamy, Philippe; Rodrigo, Rafael; Koschny, D.; Davidsson, B. J. R.; Barbieri, C.; Antonietta Barucci, M.; Bertaux, J. L.; Bertini, I.; Bodewits, D.; Cambianica, P.; Da Deppo, V.; Debei, S.; De Cecco, M.; Deller, J.; Ferrari, S.; Ferri, F.; Franceschi, M.; Fulle, M.; Gutiérrez, Pedro J.; Güttler, C.; Ip, W. H.; Keller, H. U.; Lara, L.; Lazzarin, M.; López Moreno, J. J.; Marzari, F.; Tubiana, C.; Lucchetti, A. [0000-0001-7413-3058]; Ferrari, S. [0000-0002-0157-3463]; Lara, L. [0000-0002-7184-920X]; Franceschi, M. [0000-0002-2061-0151]; Debei, S. [0000-0002-6757-6616]; Fulle, M. [0000-0001-8435-5287]; López Moreno, J. J. [0000-0002-7946-2624]; Penasa, L. [0000-0002-6394-3108]; Pajola, M. [0000-0002-3144-1277]; Ferri, F. [0000-0003-2395-5275]; Bertini, I. [0000-0002-0616-2444]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Landslides have been identified on several solar system bodies, and different mechanisms have been proposed to explain their runout length. We analyze images from the Rosetta mission and report the global characterization of such features on comet 67P/Churyumov‐Gerasimenko's surface. By assuming the height to runout length as an approximation for the friction coefficient of landslide material, we find that on comet 67P, this ratio falls between 0.50 and 0.97. Such unexpected high values reveal a rocky‐type mechanical behavior that is much more akin to Earth dry landslides than to icy satellites' mass movements. This behavior indicates that 67P and likely comets in general are characterized by consolidated materials possibly rejecting the idea that they are fluffy aggregates. The variability of the runout length among 67P landslides can be attributed to the different volatile content located in the top few meters of the cometary crust, which can drive the mass movement.