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1. Compositional properties of planet-crossing asteroids from astronomical surveys

Author

Sergeyev, A. V., Carry, B., Marsset, M., Pravec, P., Perna, D., DeMeo, F. E., Petropoulou, V., Lazzarin, M., La Forgia, F., Di Petro, I., and team, the NEOROCKS

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Context. The study of planet-crossing asteroids is of both practical and fundamental importance. As they are closer than asteroids in the Main Belt, we have access to a smaller size range, and this population frequently impacts planetary surfaces and can pose a threat to life. Aims. We aim to characterize the compositions of a large corpus of planet-crossing asteroids and to study how these compositions are related to orbital and physical parameters. Methods. We gathered publicly available visible colors of near-Earth objects (NEOs) from the Sloan Digital Sky Survey (SDSS) and SkyMapper surveys. We also computed SDSS-compatible colors from reflectance spectra of the Gaia mission and a compilation of ground-based observations. We determined the taxonomy of each NEO from its colors and studied the distribution of the taxonomic classes and spectral slope against the orbital parameters and diameter. Results. We provide updated photometry for 470 NEOs from the SDSS, and taxonomic classification of 7,401 NEOs. We classify 42 NEOs that are mission-accessible, including six of the seven flyby candidates of the ESA Hera mission. We confirm the perihelion dependance of spectral slope among S-type NEOs, likely related to a rejuvenation mechanism linked with thermal fatigue. We also confirm the clustering of A-type NEOs around 1.5-2 AU, and predict the taxonomic distribution of small asteroids in the NEO source regions in the Main Belt., Comment: 20 pages, 27 figures

Published
2023
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2. CUBES: a UV spectrograph for the future

Author

Covino, S., Cristiani, S., Alcala', J. M., Alencar, S. H. P., Balashev, S. A., Barbuy, B., Bastian, N., Battino, U., Bissell, L., Bristow, P., Calcines, A., Calderone, G., Cambianica, P., Carini, R., Carter, B., Cassisi, S., Castilho, B. V., Cescutti, G., Christlieb, N., Cirami, R., Conzelmann, R., Coretti, I., Cooke, R., Cremonese, G., Cunha, K., Cupani, G., da Silva, A. R., D'Auria, D., De Caprio, V., De Cia, A., Dekker, H., D'Elia, V., De Silva, G., Diaz, M., Di Marcantonio, P., D'Odorico, V., Ernandes, H., Evans, C., Fitzsimmons, A., Franchini, M., Gaensicke, B., Genoni, M., Giribaldi, R. E., Gneiding, C., Grazian, A., Hansen, C. J., Hopgood, J., Kosmalski, J., La Forgia, F., La Penna, P., Landoni, M., Lazzarin, M., Lunney, D., Maciel, W., Marcolino, W., Marconi, M., Migliorini, A., Miller, C., Modigliani, A., Noterdaeme, P., Oggioni, L., Opitom, C., Pariani, G., Pilecki, B., Piranomonte, S., Quirrenbach, A., Redaelli, E. M. A., Pereira, C. B., Randich, S., Rossi, S., Sanchez-Janssen, R., Schoeller, M., Seifert, W., Smiljanic, R., Snodgrass, C., Squalli, O., Stilz, I., Stuermer, J., Trost, A., Vanzella, E., Ventura, P., Verducci, O., Waring, C., Watson, S., Wells, M., Wright, D., Zafar, T., Zanutta, A., and Zins, G.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

In spite of the advent of extremely large telescopes in the UV/optical/NIR range, the current generation of 8-10m facilities is likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (>40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R>20,000, although a lower-resolution, sky-limited mode of R ~ 7,000 is also planned. CUBES will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients. The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the Phase B dedicated to detailed design and construction. First science operations are planned for 2028. In this paper, we briefly describe the CUBES project development and goals, the main science cases, the instrument design and the project organization and management., Comment: Proceedings for the HACK100 conference, Trieste, June 2022. arXiv admin note: substantial text overlap with arXiv:2208.01672

Published
2022

3. CUBES, the Cassegrain U-Band Efficient Spectrograph

Author

Cristiani, S., Alcalá, J. M., Alencar, S. H. P., Balashev, S. A., Bastian, N., Barbuy, B., Battino, U., Calcines, A., Calderone, G., Cambianica, P., Carini, R., Carter, B., Cassisi, S., Castilho, B. V., Cescutti, G., Christlieb, N., Cirami, R., Coretti, I., Cooke, R., Covino, S., Cremonese, G., Cunha, K., Cupani, G., da Silva, A. R., De Caprio, V., De Cia, A., Dekker, H., D'Elia, V., De Silva, G., Diaz, M., Di Marcantonio, P., D'Auria, D., D'Odorico, V., Fitzsimmons, A., Ernandes, H., Evans, C., Franchini, M., Genoni, M., Gänsicke, B., Giribaldi, R. E., Gneiding, C., Grazian, A., Hansen, C. J., La Forgia, F., Landoni, M., Lazzarin, M., Lunney, D., Maciel, W., Marcolino, W., Marconi, M., Migliorini, A., Miller, C., Noterdaeme, P., Opitom, C., Pariani, G., Pilecki, B., Piranomonte, S., Quirrenbach, A., Redaelli, E. M. A., Pereira, C. B., Randich, S., Rossi, S., Sanchez-Janssen, R., Seifert, W., Smiljanic, R., Snodgrass, C., Stilz, I., Stürmer, J., Vanzella, E., Ventura, P., Verducci, O., Waring, C., Watson, S., Wells, M., Wright, D., Zafar, T., and Zanutta, A.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract

In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (>40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R>20,000 (with a lower-resolution, sky-limited mode of R ~ 7,000). With the design focusing on maximizing the instrument throughput (ensuring a Signal to Noise Ratio (SNR) ~20 per high-resolution element at 313 nm for U ~18.5 mag objects in 1h of observations), it will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients. The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the detailed design and construction phase. First science operations are planned for 2028., Comment: SPIE proceedings, SPIE Astronomical Telescopes + Instrumentation 2022, Montr\'eal, Canada; 20 pages, 13 figures, 2 tables

Published
2022

4. Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov-Gerasimenko

Author

Frattin, Elisa, Bertini, I., Ivanovski, S. L., Marzari, F., Fulle, M., Zakharov, V. V., Moreno, F., Naletto, G., Lazzarin, M., Cambianica, P., Cremonese, G., Ferrari, S., Ferri, F., Guettler, C., La Forgia, F., Lucchetti, A., Pajola, M., Penasa, L., Rotundi, A., Sierks, H., and Tubiana, C.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

In this work we aim to characterise the dust motion in the inner coma of comet 67P/Churyumov- Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera onboard the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a large number of particles, performing a significant statistic of their behaviour during the post perihelion period, when the spacecraft covered distances from the nucleus ranging between 80 and 400 km. We describe the particle trajectories, investigating their orientation and finding highly radial motion with respect to the nucleus. Then, from the particle brightness profiles, we derive a particle rotational frequency of v < 3.6 Hz, revealing that they are slow rotators and do not undergo fragmentation. We use scattering models to compare the observed spectral radiance of the particles with the simulated ones in order to estimate their size, finding values that range from millimetres up to centimetres. The statistics performed in this paper provide useful parameters to constrain the cometary coma dynamical models.

Published
2021
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5. Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta

Author

Tubiana, C., Rinaldi, G., Güttler, C., Snodgrass, C., Shi, X., Hu, X., Marschall, R., Fulle, M., Bockelée-Morvan, D., Naletto, G., Capaccioni, F., Sierks, H., Arnold, G., Barucci, M. A., Bertaux, J. -L., Bertini, I., Bodewits, D., Capria, M. T., Ciarniello, M., Cremonese, G., Crovisier, J., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., De Sanctis, M. C., Davidsson, B., Doose, L., Erard, S., Filacchione, G., Fink, U., Formisano, M., Fornasier, S., Gutiérrez, P. J., Ip, W. -H., Ivanovski, S., Kappel, D., Keller, H. U., Kolokolova, L., Koschny, D., Krueger, H., La Forgia, F., Lamy, P. L., Lara, L. M., Lazzarin, M., Levasseur-Regourd, A. C., Lin, Z. -Y., Longobardo, A., López-Moreno, J. J., Marzari, F., Migliorini, A., Mottola, S., Rodrigo, R., Taylor, F., Toth, I., and Zakharov, V.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

On 27 Apr 2015, when 67P/C-G was at 1.76 au from the Sun and moving towards perihelion, the OSIRIS and VIRTIS-M instruments on Rosetta observed the evolving dust and gas coma during a complete rotation of the comet. We aim to characterize the dust, H2O and CO2 gas spatial distribution in the inner coma. To do this we performed a quantitative analysis of the release of dust and gas and compared the observed H2O production rate with the one calculated using a thermo-physical model. For this study we selected OSIRIS WAC images at 612 nm (dust) and VIRTIS-M image cubes at 612 nm, 2700 nm (H2O) and 4200 nm (CO2). We measured the average signal in a circular annulus, to study spatial variation around the comet, and in a sector of the annulus, to study temporal variation in the sunward direction with comet rotation, both at a fixed distance of 3.1 km from the comet centre. The spatial correlation between dust and water, both coming from the sun-lit side of the comet, shows that water is the main driver of dust activity in this time period. The spatial distribution of CO2 is not correlated with water and dust. There is no strong temporal correlation between the dust brightness and water production rate as the comet rotates. The dust brightness shows a peak at 0deg sub-solar longitude, which is not pronounced in the water production. At the same epoch, there is also a maximum in CO2 production. An excess of measured water production, with respect to the value calculated using a simple thermo-physical model, is observed when the head lobe and regions of the Southern hemisphere with strong seasonal variations are illuminated. A drastic decrease in dust production, when the water production (both measured and from the model) displays a maximum, happens when typical Northern consolidated regions are illuminated and the Southern hemisphere regions with strong seasonal variations are instead in shadow., Comment: 15 pages, accepted for publication in A&A

Published
2019
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6. ROSETTA/OSIRIS observations of the 67P nucleus during the April 2016 flyby: high-resolution spectrophotometry

Author

Feller, C., Fornasier, S., Ferrari, S., Hasselmann, P. H., Barucci, A., Massironi, M., Deshapriya, J. D. P, Sierks, H., Naletto, G., Lamy, P. L., Rodrigo, R., Koschny, D., Davidsson, B. J. R., Bertaux, J. -L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Fulle, M., Gutiérrez, P. 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., and Scholten, F.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

In April 2016, the Rosetta spacecraft performed a low-altitude low-phase-angle flyby over the Imhotep-Khepry transition of 67P/Churyumov-Gerasimenko's nucleus. The OSIRIS/Narrow-Angle-Camera (NAC) acquired 112 images with mainly 3 broadband filters in the visible at a resolution of up to 0.53 m/px and for phase angles between 0.095{\deg} and 62{\deg}. Using those images, we have investigated the morphological and spectrophotometrical properties of this area. We assembled the images into coregistered color cubes. Using a 3D shape model, we produced the illumination conditions and georeference for each image. We projected the observations on a map 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. This region of the nucleus hosts numerous and varied types of terrains and features. We observe an association between a feature's nature, its reflectance, and its spectral slope. 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{\pm}0.001{\%}/100nm/{\deg} at 2.7 au outbound, similarly to the one obtained at 2.3 au inbound during the February 2015 flyby. 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., Comment: 23 pages, 14 figures, 5 tables

Published
2018
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7. Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko

Author

Fornasier, S., Hoang, V. H., Hasselmann, P. H., Feller, C., Barucci, M. A., Deshapriya, J. D. P., Sierks, H., Naletto, G., Lamy, P. L., Rodrigo, R., Koschny, D., Davidsson, B., Agarwal, J., Barbieri, C., Bertaux, J. -L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., Ferrari, S., Fulle, M., Gutierrez, P. J., Guttler, C., Ip, W. -H., Keller, H. U., Küppers, M., La Forgia, F., Lara, M. L., Lazzarin, M., Lin, Z-Y, Moreno, J. J. Lopez, Marzari, F., Mottola, S., Pajola, M., Shi, X., Toth, I., and Tubiana, C.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The Rosetta space probe accompanied comet 67P/Churyumov-Gerasimenko for more than two years, obtaining an unprecedented amount of unique data of the comet nucleus and inner coma. This work focuses identifying the source regions of faint jets and outbursts and on studying the spectrophotometric properties of some outbursts. We use observations acquired with the OSIRIS/NAC camera during July-October 2015, that is, close to perihelion. More than 200 jets of different intensities were identified directly on the nucleus. Some of the more intense outbursts appear spectrally bluer than the comet dark terrain in the vivible-to-near-infrared region. We attribute this spectral behavior to icy grains mixed with the ejected dust. Some of the jets have an extremely short lifetime. They appear on the cometary surface during the color sequence observations, and vanish in less than some few minutes after reaching their peak. We also report a resolved dust plume observed in May 2016 at a resolution of 55 cm/pixel, which allowed us to estimate an optical depth of $\sim$0.65 and an ejected mass of $\sim$ 2200 kg. We present the results on the location, duration, and colors of active sources on the nucleus of 67P from the medium-resolution (i.e., 6-10 m/pixel) images acquired close to perihelion passage. The observed jets are mainly located close to boundaries between different morphological regions. Jets depart not only from cliffs, but also from smooth and dust-covered areas, from fractures, pits, or cavities that cast shadows and favor the recondensation of volatiles. This study shows that faint jets or outbursts continuously contribute to the cometary activity close to perihelion passage, and that these events are triggered by illumination conditions. Faint jets or outbursts are not associated with a particular terrain type or morphology., Comment: Accepted for publication on Astronomy and Astrophysics on 27 August 2018. 27 pages, 18 figures, 2 tables

Published
2018
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8. Changes in the physical environment of the inner coma of 67P/Churyumov-Gerasimenko with decreasing heliocentric distance

Author

Bodewits, D., Lara, L. M., A'Hearn, M. F., La Forgia, F., Giquel, A., Kovacs, G., Knollenberg, J., Lazzarin, M., Lin, Z. -Y., Shi, X., Snodgrass, C., Tubiana, C., Sierks, H., Barbieri, C., Lamy, P. M., Rodrigo, R., Koschny, D., Rickman, H., Keller, H. U., Barucci, M. A., Bertaux, J. -L., Bertini, I., Boudreault, S., Cremonese, G., DaDeppo, V., Davidsson, B., Debei, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Guettler, C., Hviid, S. F., Ip, W. -H., Jorda, L., Kramm, J. -R., Kuehrt, E., Kueppers, M., Lopez-Moreno, J. J., Marzari, F., Naletto, G., Oklay, N., Thomas, N., Toth, I., and Vincent, J. -B.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The Wide Angle Camera of the OSIRIS instrument on board the Rosetta spacecraft is equipped with several narrowband filters that are centered on the emission lines and bands of various fragment species. These are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of comet 67P with time and heliocentric distance, here between 2.6 - 1.3 AU pre-perihelion. Our observations indicate that the emission observed in the OH, OI, CN, NH, and NH2 filters is mostly produced by dissociative electron impact excitation of different parent species. We conclude that CO2 rather than H2O is a significant source of the [OI] 630 nm emission. A strong plume-like feature observed in the in CN and [OI] filters is present throughout our observations. This plume is not present in OH emission and indicates a local enhancement of the CO2/H2O ratio by as much as a factor of 3. We observed a sudden decrease in intensity levels after March 2015, which we attribute to decreased electron temperatures in the first kilometers above the nucleus surface., Comment: 6 figures, 6 tables

Published
2016
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9. Observations and analysis of a curved jet in the coma of comet 67P/Churyumov-Gerasimenko

Author

Lin, Zhong-Yi, Lai, I. -L., Su, C. -C., Ip, W. -H., Lee, J. -C., Wu, J. -S., Vincent, J. -B., La Forgia, F., Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H. U., Agarwal, J., A'Hearn, M. F., Barucci, M. A., Bertaux, J. -L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Davidsson, B., Debet, S., De Cecco, M., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Guttler, C., Hviid, S. F., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R., Kuhrt, E., Kuppers, M., Lara, L. M., Lazzarin, M., Lopez-Moreno, J. J., Lowry, S., Marzari, F., Michalik, H., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Rozek, A., Thomas, N., and Tubiana, C.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

We analyze the physical properties and dynamical origin of a curved jet of comet 67P/Churyumov-Gerasimenko that was observed repeatedly in several nucleus rotations starting on May 30 and persisting until early August, 2015. We simulated the motion of dust grains ejected from the nucleus surface under the influence of the gravity and viscous drag effect of the expanding gas flow from the rotating nucleus. The formation of the curved jet is a combination of the size of the dust particles (~0.1-1 mm) and the location of the source region near the nucleus equator. This enhances the spiral feature of the collimated dust stream after the dust is accelerated to a terminal speed on the order of m/s., Comment: 5pages, 5 figures

Published
2016
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10. Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft

Author

Fornasier, S., Hasselmann, P. H., Barucci, M. A., Feller, C., Besse, S., Leyrat, C., Lara, L., Gutierrez, P. J., Oklay, N., Tubiana, C., Scholten, F., Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H. U., Agarwal, J., A'Hearn, M. F., Bertaux, J. -L., Bertini, I., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Fulle, M., Groussin, O., Güttler, C., Hviid, S. F., Ip, W., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, R., Kührt, E., Küppers, M., La Forgia, F., Lazzarin, M., Moreno, J. J. Lopez, Marzari, F., Matz, K. -D., Michalik, H., Moreno, F., Mottola, S., Naletto, G., Pajola, M., Pommerol, A., Preusker, F., Shi, X., Snodgrass, C., Thomas, N., and Vincent, J. -B.

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The Rosetta mission of the European Space Agency has been orbiting the comet 67P/Churyumov-Gerasimenko (67P) since August 2014 and is now in its escort phase. A large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted are onboard Rosetta. We present results for the photometric and spectrophotometric properties of the nucleus of 67P derived from the OSIRIS imaging system, which consists of a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). The disk-averaged phase function of the nucleus of 67P shows a strong opposition surge with a G parameter value of -0.13$\pm$0.01 in the HG system formalism and an absolute magnitude $H_v(1,1,0)$ = 15.74$\pm$0.02 mag. The integrated spectrophotometry in 20 filters covering the 250-1000 nm wavelength range shows a red spectral behavior, without clear absorption bands except for a potential absorption centered at $\sim$ 290 nm that is possibly due to SO$_2$ ice. The nucleus shows strong phase reddening, with disk-averaged spectral slopes increasing from 11\%/(100 nm) to 16\%/(100 nm) in the 1.3$^{\circ}$--54$^{\circ}$ phase angle range. The geometric albedo of the comet is 6.5$\pm$0.2\% at 649 nm, with local variations of up to $\sim$ 16\% in the Hapi region. From the disk-resolved images we computed the spectral slope together with local spectrophotometry and identified three distinct groups of regions (blue, moderately red, and red). The Hapi region is the brightest, the bluest in term of spectral slope, and the most active surface on the comet. Local spectrophotometry shows an enhancement of the flux in the 700-750 nm that is associated with coma emissions., Comment: 18, pages, 14 figures, Astronomy and Astrophysics, in press

Published
2015
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13. Bilobate comet morphology and internal structure controlled by shear deformation

Author

Matonti, C., Attree, N., Groussin, O., Jorda, L., Viseur, S., Hviid, S. F., Bouley, S., Nébouy, D., Auger, A.-T., Lamy, P. L., Sierks, H., Naletto, G., Rodrigo, R., Koschny, D., Davidsson, B., Barucci, M. A., Bertaux, J.-L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, V., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Fulle, M., Gutiérrez, P. J., Güttler, C., Ip, W.-H., Keller, H. U., Lara, L. M., La Forgia, F., Lazzarin, M., Lucchetti, A., López-Moreno, J. J., Marzari, F., Massironi, M., Mottola, S., Oklay, N., Pajola, M., Penasa, L., Preusker, F., Rickman, H., Scholten, F., Shi, X., Toth, I., Tubiana, C., and Vincent, J.-B.

Published
2019
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14. On the nucleus structure and activity of comet 67P/Churyumov-Gerasimenko

Author

Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, H., Keller, H. U., Agarwal, J., A'Hearn, M. F., Angrilli, F., Auger, A.-T., Barucci, M. A., Bertaux, J.-L., Bertini, I., Besse, S., Bodewits, D., Capanna, C., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Ferri, F., Fornasier, S., Fulle, M., Gaskell, R., Giacomini, L., Groussin, O., Gutierrez-Marques, P., Gutiérrez, P. J., Güttler, C., Hoekzema, N., Hviid, S. F., Ip, W.-H., Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J.-R., Kührt, E., Küppers, M., La Forgia, F., Lara, L. M., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Magrin, S., Marchi, S., Marzari, F., Massironi, M., Michalik, H., Moissl, R., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pertile, M., Preusker, F., Sabau, L., Scholten, F., Snodgrass, C., Thomas, N., Tubiana, C., Vincent, J.-B., Wenzel, K.-P., Zaccariotto, M., and Pätzold, M.

Published
2015

15. The morphological diversity of comet 67P/Churyumov-Gerasimenko

Author

Thomas, N., Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Rickman, H., Koschny, D., Keller, H. U., Agarwal, J., A'Hearn, M. F., Angrilli, F., Auger, A.-T., Barucci, M. A., Bertaux, J.-L., Bertini, I., Besse, S., Bodewits, D., Cremonese, G., Da Deppo, V., Davidsson, B., De Cecco, M., Debei, S., El-Maarry, M. R., Ferri, F., Fornasier, S., Fulle, M., Giacomini, L., Groussin, O., Gutierrez, P. J., Güttler, C., Hviid, S. F., Ip, W.-H., Jorda, L., Knollenberg, J., Kramm, J.-R., Kührt, E., Küppers, M., La Forgia, F., Lara, L. M., Lazzarin, M., Moreno, J. J. Lopez, Magrin, S., Marchi, S., Marzari, F., Massironi, M., Michalik, H., Moissl, R., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Sabau, L., Scholten, F., Snodgrass, C., Tubiana, C., Vincent, J.-B., and Wenzel, K.-P.

Published
2015

17. Comets beyond 4 au: How pristine are Oort nuclei?

Author

FULLE, Marco, Lazzarin, M., La Forgia, F., Zakharov, V. V., Bertini, I., Epifani, E. Mazzotta, Ammannito, E., BUZZONI, Alberto, CAPRIA, MARIA TERESA, CARBOGNANI, Albino, Da Deppo, V., Corte, V. Della, Fiscale, S., Frattin, E., INNO, LAURA, MIGLIORINI, Alessandra, PERNECHELE, Claudio, Rotundi, Alessandra, Sindoni, G., Tubiana, C., Milani, G., Aletti, A., Bacci, P., Baj, G., Bellini, F., Bryssinck, E., Di Grazia, M., Facchini, M., Feraco, M., Guido, E., Ligustri, R., Kugel, F., Maestripieri, M., Tirelli, D., Valvasori, A., Snodgrass, C., and Jones, G. H.

Subjects
Space and Planetary Science, space vehicles, Oort Cloud, Astronomy and Astrophysics, protoplanetary discs, general [comets]
Abstract

The ESA mission Comet Interceptor will target an Oort or interstellar comet during its first approach to the Sun. Meanwhile, the Vera Rubin LSST Survey will observe hundreds of active comets per month beyond 4 au from the Sun, where water vapor pressure is expected to be too low to eject dust. We discuss observations of dust tails at heliocentric distances larger than 4 au in order to retrieve the physical parameters driving cometary activity beyond Jupiter by means of a probabilistic tail model, which is consistent with the activity model defining the gas coma parameters due to the sublimation of carbon monoxide, molecular oxygen, methane, ethane and carbon dioxide since the activity onset at 85 au from the Sun. We find that: (i) All the observed dust tails are consistent with the adopted activity model; (ii) The tail fits depend on three free parameters only, all correlated to the nucleus size; (iii) Tail fits are always improved by anisotropic dust ejection, suggesting activity of Oort nuclei dominated by seasons; (iv) Inbound seasons suggest cometary activity before the ejection of protocomets into the Oort cloud, as predicted by the activity model; (v) Oort nuclei larger than 1 km may be characterized by a fallout up to ≈100 m thick deposited during ≈60 yr inbound; (vi) On the other side, Oort nuclei smaller than 1 km may appear more pristine than Jupiter Family Comets when observed at 1 au from the Sun.

Published
2022

18. Rotational Resolved Spectroscopy of the Didymos System, Target of the DART/LICIACube Mission

Author

Ieva, S., Mazzotta Epifani, E., Dotto, E., Perna, D., Brucato, J. R., Poggiali, G., Pajola, M., Lazzarin, M., La Forgia, F., Rossi, A., Palumbo, P., Della Corte, V., Migliorini, A., Zannoni, M., Snodgrass, C., Pravec, P., Granvik, M., Lucchetti, A., Ivanovski, S., Meneghin, A., Amoroso, M., Pirrotta, S., Bertini, I., Capannolo, A., Cotugno, B., Cremonese, G., Di Tana, V., Gai, I., Impresario, G., Lavagna, M., Miglioretti, F., Modenini, D., Simioni, E., Simonetti, S., Tortora, P., Zanotti, G., Zinzi, A., Thomas, C., and Rivkin, A. S.

Published
2021

20. Rotational Properties of Binary Asteroid System (65803) Didymos, Target of the DART/LICIACube and HERA Missions

Author

Ieva, S., Mazzotta Epifani, E., Dotto, E., Perna, D., Brucato, J. R. search by orcid, Poggiali, G., Pajola, M., Lazzarin, M., La Forgia, F., Rossi, A., Palumbo, P., Della Corte, V., Migliorini, A., Zannoni, M., Snodgrass, C., Pravec, P., Granvik, M., Lucchetti, A. search by orcid, Ivanovski, S., Meneghin, A. Amoroso, M., Pirrotta, S., Bertini, I., Capannolo, A., Cotugno, B., Cremonese, G., Di Tana, V., Gai, I., Impresario, G., Lavagna, M., Miglioretti, F., Modenini, D., Simioni, E., Simonetti, S., Tortora, P., Zanotti, G., Zinzi, A., Thomas, C., and Rivkin, A. S.

Subjects
Near Earth Asteroids, DART/LICIACube mission, Spectroscopy
Abstract

Near-Earth objects (NEOs), due to their proximity to our planet, represent one of the most accessible bodies in the whole Solar System. Their investigation can provide answers to several pressing questions in modern planetology (regarding, e.g., planetary formation, delivery of water and organics to the early Earth, and emergence of life). Moreover, water and valued minerals stored inside NEOs have already intrigued governments and private companies, allured by the idea of exploiting resources through asteroid mining. However, NEOs can represent a risk for future human civilization, since some of them can be potential impactors. To this purpose, the NASA Double Asteroid Redirection Test (DART) has been approved to be the first demonstration of an hazard mitigation of an asteroid by using a kinetic impactor.

Published
2021

22. Spectroscopic Characterization of the Didymos System, Target of the Kinetic Impactor Dart/liciacube Mission

Author

Ieva, S., Mazzotta Epifani, E., Dotto, E., Perna, D., Brucato, J. R., Poggiali, G., Pajola, M., Lazzarin, M., La Forgia, F., Rossi, A., Palumbo, P., Della Corte, V., Migliorini, A., Zannoni, M., Snodgrass, C., Pravec, P., Granvik, M., Lucchetti, A., Ivanovski, S., Meneghin, A., Amoroso, M., Pirrotta, S., Bertini, I., Capannolo, A., Cotugno, B., Cremonese, G., Di Tana, V., Gai, I., Impresario, G., Lavagna, M., Miglioretti, F., Modenini, D., Simioni, E., Simonetti, S., Tortora, P., Zanotti, G., Zinzi, A., Thomas, C., and Rivkin, A. S.

Published
2021

23. Rotational Properties of Binary Asteroid System (65803) Didymos, Target of the DART/LICIACube and HERA Missions

Author

Mazzotta Epifani, E., Dotto, E., Ieva, S., Perna, D., Della Corte, V., Migliorini, A., Pajola, M., Brucato, J. R. search by orcid, Poggiali, G., Rossi, A., Palumbo, P., Lazzarin, M., La Forgia, F., Zannoni, M., Snodgrass, C., Pravec, P., Granvik, M., Lucchetti, A. search by orcid, Ivanovski, S., Cremonese, Amoroso, G., Pirrotta, S., Bertini, I., Capannolo, A., Cotugno, B., Di Tana, V., Gai, I., Impresario, G., Lavagna, M., Meneghin, A., Miglioretti, F., Modenini, D., Simioni, E., Simonetti, S., Tortora, P., Zanotti, G., Zinzi, A., Thomas, C., Rivkin, A., and Dall'Ora, M.

Published
2021

25. Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov–Gerasimenko

Author

Frattin, E, primary, Bertini, I, additional, Ivanovski, S L, additional, Marzari, F, additional, Fulle, M, additional, Zakharov, V V, additional, Moreno, F, additional, Naletto, G, additional, Lazzarin, M, additional, Cambianica, P, additional, Cremonese, G, additional, Ferrari, S, additional, Ferri, F, additional, Güttler, C, additional, La Forgia, F, additional, Lucchetti, A, additional, Pajola, M, additional, Penasa, L, additional, Rotundi, A, additional, Sierks, H, additional, and Tubiana, C, additional

Published
2021
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26. Time evolution of dust deposits in the Hapi region of comet 67P/Churyumov-Gerasimenko

Author

German Centre for Air and Space Travel, Centre National de la Recherche Scientifique (France), Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), Government of Sweden, Cambianica, P., Fulle, M., Cremonese, G., Simioni, E., Naletto, G., Massironi, M., Penasa, L., Lucchetti, A., Pajola, M., Bertini, I., Bodewits, D., Ceccarelli, C., Ferri, F., Fornasier, S., Frattin, E., Güttler, C., Gutiérrez, Pedro J., Keller, H.U., Kührt, E., Küppers, M., La Forgia, F., Lazzarin, M., Marzari, F., Mottola, S., Sierks, H., Toth, I., Tubiana, C., Vincent, J.B., German Centre for Air and Space Travel, Centre National de la Recherche Scientifique (France), Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), Government of Sweden, Cambianica, P., Fulle, M., Cremonese, G., Simioni, E., Naletto, G., Massironi, M., Penasa, L., Lucchetti, A., Pajola, M., Bertini, I., Bodewits, D., Ceccarelli, C., Ferri, F., Fornasier, S., Frattin, E., Güttler, C., Gutiérrez, Pedro J., Keller, H.U., Kührt, E., Küppers, M., La Forgia, F., Lazzarin, M., Marzari, F., Mottola, S., Sierks, H., Toth, I., Tubiana, C., and Vincent, J.B.

Abstract

Aims. We provide a measurement of the seasonal evolution of the dust deposit erosion and accretion in the Hapi region of comet 67P/Churyumov-Gerasimenko with a vertical accuracy of 0.2-0.9 m. Methods. We used OSIRIS Narrow Angle Camera images with a spatial scale of lower than 1.30 m px-1 and developed a tool to monitor the time evolution of 22 boulder heights with respect to the surrounding dust deposit. The tool is based on the measurement of the shadow length projected by the boulder on the surrounding pebble deposit. Assuming the position of the boulders does not change during the observational period, boulder height variations provide an indication of how the thickness of the surrounding dust layer varies over time through erosion and accretion phenomena. Results. We measured an erosion of the dust deposit of 1.7 ± 0.2 m during the inbound orbit until 12 December, 2014. This value nearly balances the fallout from the southern hemisphere during perihelion cometary activity. During the perihelion phase, the dust deposit then increased by 1.4 ± 0.8 m. This is interpreted as a direct measurement of the fallout thickness. By comparing the erosion rate and dust volume loss rate at the Hapi region measured in the coma, the fallout represents ~96% in volume of the ejecta. The amount of the eroded pristine material from the southern hemisphere, together with its subsequent transport and fallout on the nucleus, led us to discuss the pristine water ice abundance in comet 67P. We determine that the refractory-to-ice mass ratio ranges from 6 to 110 in the perihelion-eroded pristine nucleus, providing a pristine ice mass fraction of (8 ± 7)% in mass. © 2020 ESO.

Published
2020

28. Time evolution of dust deposits in the Hapi region of comet 67P/Churyumov-Gerasimenko

Author

Cambianica, P., primary, Fulle, M., additional, Cremonese, G., additional, Simioni, E., additional, Naletto, G., additional, Massironi, M., additional, Penasa, L., additional, Lucchetti, A., additional, Pajola, M., additional, Bertini, I., additional, Bodewits, D., additional, Ceccarelli, C., additional, Ferri, F., additional, Fornasier, S., additional, Frattin, E., additional, Güttler, C., additional, Gutiérrez, P. J., additional, Keller, H. U., additional, Kührt, E., additional, Küppers, M., additional, La Forgia, F., additional, Lazzarin, M., additional, Marzari, F., additional, Mottola, S., additional, Sierks, H., additional, Toth, I., additional, Tubiana, C., additional, and Vincent, J.-B., additional

Published
2020
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29. CUBES: the Cassegrain U-band Efficient Spectrograph

Author

Evans, Christopher J., Bryant, Julia J., Motohara, Kentaro, Cristiani, S., Alcalá, J. M., Alencar, S. H. P., Balashev, S., Bastian, N., Barbuy, B., Battino, U., Calcines, A., Calderone, G., Cambianica, P., Carini, R., Carter, B., Cassisi, S., Castilho, B., Cescutti, G., Christlieb, N., Cirami, R., Coretti, I., Cooke, R. J., Covino, S., Cremonese, G., Cunha, K., Cupani, G., da Silva, A., De Caprio, V., De Cia, A., Dekker, H., D'Elia, V., de Silva, G., Diaz, M. P., Di Marcantonio, P., D'Auria, D., D'Odorico, V., Fitzsimmons, A., Ernandes, H., Evans, C., Franchini, M., Genoni, M., Gänsicke, B., Giribaldi, R. E., Gneiding, C., Grazian, A., Hansen, C. J., La Forgia, F., Landoni, M., Lazzarin, M., Lunney, D., Maciel, W. J., Marcolino, W., Marconi, M., Migliorini, A., Miller, C., Noterdaeme, P., Opitom, C., Pariani, G., Pilecki, B., Piranomonte, S., Quirrenbach, A., Redaelli, E. M. A., Pereira, C., Randich, S., Rossi, S., Sanchez-Janssen, R., Seifert, W., Smiljanic, R., Snodgrass, C., Stilz, I., Stürmer, J., Vanzella, E., Ventura, P., Verducci, O., Waring, C., Watson, S., Wells, M., Wright, D., Zafar, T., and Zanutta, A.

Published
2022
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30. Spectrophotometric variegation of the layering in comet 67P/Churyumov-Gerasimenko as seen by OSIRIS

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Tognon, G, Ferrari, S., Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Cambianica, P., Lucchetti, A., Pajola, M., Ferri, F., Güttler, C., Davidsson, B., Deshapriya, P, Fornasier, S., Mottola, S., Toth, I., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Barbieri, C, Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, E., Fulle, M., Gutiérrez, Pedro J., Ip, W. H., Keller, H.U., Lara, Luisa María, López-Moreno, José Juan, Marzari, F., Petropoulou, V., Shi, X., Tubiana, C., German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Tognon, G, Ferrari, S., Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Cambianica, P., Lucchetti, A., Pajola, M., Ferri, F., Güttler, C., Davidsson, B., Deshapriya, P, Fornasier, S., Mottola, S., Toth, I., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Barbieri, C, Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, E., Fulle, M., Gutiérrez, Pedro J., Ip, W. H., Keller, H.U., Lara, Luisa María, López-Moreno, José Juan, Marzari, F., Petropoulou, V., Shi, X., and Tubiana, C.

Abstract

Between August 2014 and September 2016, the ESA space mission Rosetta escorted comet 67P/Churyumov-Gerasimenko (67P) during its perihelion passage. The onboard OSIRIS Narrow Angle Camera (NAC) acquired high-resolution multispectral images of the cometary surface. These datasets allowed a characterization of the spectrophotometric variegation of the layering of the large lobe, correlated with the layer structural elevation. Aims. We perform a spectrophotometric characterization of the outcropping stratification of the small lobe of 67P as a function of its structural elevation, and consequently, a spectrophotometric comparison of the layered outcrops of the two lobes. Methods. We selected two sequences of post-perihelion OSIRIS NAC images (similar to 2.4 au outbound to the Sun), from which we built up two multispectral images, framing an extended geological section of the onion-like stratification of the small lobe. Then we classified the consolidated areas of the outcropping and the relative coarse deposits that were identified in the multispectral data with a two-class maximum likelihood method. For this, we defined the classes as a function of the structural elevation of the surface. Results. As a result, we identified a brightness variegation of the surface reflectance that is correlated with the structural elevation. The outer class, which is located at higher elevations, appears darker than the inner class. This fits previously obtained results for the large lobe. The reflectance values of the nucleus of 67P tend to decrease with increasing structural elevation. Conclusions. The observed spectrophotometric variegation can be due to a different texture as well as to a different content of volatiles and refractories. We suggest that the outer outcrops appear darker because they have been exposed longer, and the inner outcrops appear brighter because the surface has been more effectively rejuvenated. We interpret this variegation as the result of an evolutionary p

Published
2019

31. Rosetta/OSIRIS observations of the 67P nucleus during the April 2016 flyby: high-resolution spectrophotometry

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Feller, C., Fornasier, S., Ferrari, S., Hasselmann, P.H., Barucci, A, Massironi, M., Deshapriya, J.D.P., Sierks, H., Naletto, G., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, Björn J. R., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Shi, X., Tubiana, C., Gaskell, B, La Forgia, F., Lucchetti, A., Mottola, S., Pajola, M., Preusker, F., Scholten, F., German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Feller, C., Fornasier, S., Ferrari, S., Hasselmann, P.H., Barucci, A, Massironi, M., Deshapriya, J.D.P., Sierks, H., Naletto, G., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, Björn J. R., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Marzari, F., Shi, X., Tubiana, C., Gaskell, B, La Forgia, F., Lucchetti, A., Mottola, S., Pajola, M., Preusker, F., and Scholten, F.

Abstract

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 degrees and 62 degrees. 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/degrees 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

Published
2019

32. Quantitative analysis of isolated boulder fields on comet 67P/Churyumov-Gerasimenko

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Cambianica, P., Cremonese, G., Naletto, G., Lucchetti, A., Pajola, M., Penasa, L., Simioni, E., Massironi, M., Ferrari, S., Bodewits, D., La Forgia, F., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Dayidsson, B, Barucci, M.A., Bertaux, J.L., Bertini, I., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Fornasier, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Lara, Luisa María, Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Mottola, S., Shi, X., Scholten, F., Toth, I., Tubiana, C., Vincent, J.B., German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Cambianica, P., Cremonese, G., Naletto, G., Lucchetti, A., Pajola, M., Penasa, L., Simioni, E., Massironi, M., Ferrari, S., Bodewits, D., La Forgia, F., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Dayidsson, B, Barucci, M.A., Bertaux, J.L., Bertini, I., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Fornasier, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Lara, Luisa María, Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Mottola, S., Shi, X., Scholten, F., Toth, I., Tubiana, C., and Vincent, J.B.

Abstract

We provide a detailed quantitative analysis of isolated boulder fields situated in three different regions of comet 67P/Churyumov-Gerasimenko: Imhotep, Hapi, and Hatmehit. This is done to supply a useful method for analyzing the morphology of the boulders and to characterize the regions themselves. Methods. We used OSIRIS Narrow Angle Camera images with a spatial scale smaller than 2 mpx(-1) and analyzed the size-frequency distribution and the cumulative fractional area per boulder population. In addition, we correlated shape parameters, such as circularity and solidity, with both the spatial and the size-frequency distribution of the three populations. Results. We identified 11 811 boulders in the Imhotep, Hapi, and Hatmehit regions. We found that the Hatmehit and Imhotep areas show power indices in the range of -2.3/-2.7. These values could represent a transition between gravitational events caused by thermal weathering and sublimation, and material formed during collapses that has undergone sublimation. The Hapi area is characterized by a lower power index (-1.2/-1.7), suggesting that those boulders have a different origin. They can be the result of material formed during gravitational events and collapses that has undergone continuous fragmentation. We calculated the cumulative fractional area (CFA) in order to investigate how the area is covered by boulders as a function of their sizes. The Hatmehit and Imhotep regions show a CFA that is well fit by a power law. In contrast, the Hapi area does not show the same trend. We analyzed the fractal distributions, finding that the populations seem to be fractal at all dimensions, except for the Hapi distribution, which shows a possible fractal behavior for small dimensions only. Finally, the average values of the shape parameters reveal solid and roundish boulders in all populations we studied.© ESO 2019

Published
2019

33. Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta

Author

Agenzia Spaziale Italiana, German Research Foundation, Centre National de la Recherche Scientifique (France), Ministerio de Economía y Competitividad (España), Government of Sweden, European Space Agency, l'Observatoire de Paris, Science and Technology Facilities Council (UK), Tubiana, C., Rinaldi, G., Güttler, C., Snodgrass, C, Shi, X., Hu, X., Marschall, R., Fulle, M., Bockelée-Morvan, D., Naletto, G., Capaccioni, F, Sierks, H., Arnold, G., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Capria, MT, Ciarniello, M, Cremonese, G., Crovisier, J, Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., De Sanctis, MC, Davidsson, B., Doose, L, Erard, S, Filacchione, G., Fink, U, Formisano, M, Fornasier, S., Gutiérrez, Pedro J., Ip, W. H., Ivanovski, S., Kappel, D, Keller, H.U., Kolokolova, L., Koschny, D., Krueger, H, La Forgia, F., Lamy, P.L., Lara, Luisa María, Lazzarin, M., Levasseur-Regourd, A. C., Lin, Zhong-Yi, Longobardo, A, López-Moreno, José Juan, Marzari, F., Migliorini, A, Mottola, S., Rodrigo Montero, Rafael, Taylor, F, Toth, I., Zakharov, V, Agenzia Spaziale Italiana, German Research Foundation, Centre National de la Recherche Scientifique (France), Ministerio de Economía y Competitividad (España), Government of Sweden, European Space Agency, l'Observatoire de Paris, Science and Technology Facilities Council (UK), Tubiana, C., Rinaldi, G., Güttler, C., Snodgrass, C, Shi, X., Hu, X., Marschall, R., Fulle, M., Bockelée-Morvan, D., Naletto, G., Capaccioni, F, Sierks, H., Arnold, G., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Capria, MT, Ciarniello, M, Cremonese, G., Crovisier, J, Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., De Sanctis, MC, Davidsson, B., Doose, L, Erard, S, Filacchione, G., Fink, U, Formisano, M, Fornasier, S., Gutiérrez, Pedro J., Ip, W. H., Ivanovski, S., Kappel, D, Keller, H.U., Kolokolova, L., Koschny, D., Krueger, H, La Forgia, F., Lamy, P.L., Lara, Luisa María, Lazzarin, M., Levasseur-Regourd, A. C., Lin, Zhong-Yi, Longobardo, A, López-Moreno, José Juan, Marzari, F., Migliorini, A, Mottola, S., Rodrigo Montero, Rafael, Taylor, F, Toth, I., and Zakharov, V

Abstract

On 27 April 2015, when comet 67P/Churyumov-Gerasimenko was at 1.76 au from the Sun and moving toward perihelion, the OSIRIS and VIRTIS-M instruments on board the Rosetta spacecraft simultaneously observed the evolving dust and gas coma during a complete rotation of the comet.© C. Tubiana et al. 2019

Published
2019

34. Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko

Author

Federal Ministry of Education and Research (Germany), Agence Nationale de la Recherche (France), Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), Government of Sweden, Fornasier, S., Hoang, VH, Hasselmann, P.H., Feller, C., Barucci, M.A., Deshapriya, J.D.P., Sierks, H., Naletto, G., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Agarwal, J., Barbieri, C, Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Ferrari, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Küppers, M., La Forgia, F., Lara, Luisa María, Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Mottola, S., Pajola, M., Shi, X., Toth, I., Tubiana, C., Federal Ministry of Education and Research (Germany), Agence Nationale de la Recherche (France), Agenzia Spaziale Italiana, Ministerio de Ciencia, Innovación y Universidades (España), Government of Sweden, Fornasier, S., Hoang, VH, Hasselmann, P.H., Feller, C., Barucci, M.A., Deshapriya, J.D.P., Sierks, H., Naletto, G., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Agarwal, J., Barbieri, C, Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Ferrari, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Ip, W. H., Keller, H.U., Küppers, M., La Forgia, F., Lara, Luisa María, Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Mottola, S., Pajola, M., Shi, X., Toth, I., and Tubiana, C.

Abstract

The Rosetta space probe accompanied comet 67P/Churyumov-Gerasimenko for more than two years, obtaining an unprecedented amount of unique data of the comet nucleus and inner coma. This has enabled us to study its activity almost continuously from 4 au inbound to 3.6 au outbound, including the perihelion passage at 1.24 au. This work focuses identifying the source regions of faint jets and outbursts and on studying the spectrophotometric properties of some outbursts. We use observations acquired with the OSIRIS/NAC camera during July-October 2015, that is, close to perihelion. Methods. We analyzed more than 2000 images from NAC color sequences acquired with 7-11 filters covering the 250-1000 nm wavelength range. The OSIRIS images were processed with the OSIRIS standard pipeline up to level 3, that is, converted in radiance factor, then corrected for the illumination conditions. For each color sequence, color cubes were produced by stacking registered and illumination-corrected images. Results. More than 200 jets of different intensities were identified directly on the nucleus. Some of the more intense outbursts appear spectrally bluer than the comet dark terrain in the visible-to-near-infrared region. We attribute this spectral behavior to icy grains mixed with the ejected dust. Some of the jets have an extremely short lifetime. They appear on the cometary surface during the color sequence observations, and vanish in less than some few minutes after reaching their peak. We also report a resolved dust plume observed in May 2016 at a resolution of 55 cm pixel(-1), which allowed us to estimate an optical depth of similar to 0.65 and an ejected mass of similar to 2200 kg, assuming a grain bulk density of similar to 800 kg m(-3). We present the results on the location, duration, and colors of active sources on the nucleus of 67P from the medium-resolution (i.e., 6-10 m pixel(-1)) images acquired close to perihelion passage. The observed jets are mainly located close to bou

Published
2019

35. Multidisciplinary analysis of the Hapi region located on Comet 67P/Churyumov-Gerasimenko

Author

European Space Agency, Swedish National Space Board, Ministerio de Educación y Ciencia (España), Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, German Centre for Air and Space Travel, Pajola, M., Lee, J.C., Oklay, N., Hviid, S.F., Penasa, L., Mottola, S., Shi, X., Fornasier, S., Davidsson, B., Giacomini, L., Lucchetti, A., Massironi, M., Vincent, J.B., Bertini, I., Naletto, G., Ip, W. H., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Keller, H.U., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bodewits, D., Cambianica, P., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., El Maarry, M. R., Feller, C., Ferrari, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Lara, Luisa María, La Forgia, F., Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Preusker, F., Scholten, F., Toth, I., Tubiana, C., European Space Agency, Swedish National Space Board, Ministerio de Educación y Ciencia (España), Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, German Centre for Air and Space Travel, Pajola, M., Lee, J.C., Oklay, N., Hviid, S.F., Penasa, L., Mottola, S., Shi, X., Fornasier, S., Davidsson, B., Giacomini, L., Lucchetti, A., Massironi, M., Vincent, J.B., Bertini, I., Naletto, G., Ip, W. H., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Keller, H.U., Agarwal, J., Barucci, M.A., Bertaux, J.L., Bodewits, D., Cambianica, P., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., El Maarry, M. R., Feller, C., Ferrari, S., Fulle, M., Gutiérrez, Pedro J., Güttler, C., Lara, Luisa María, La Forgia, F., Lazzarin, M., Lin, Zhong-Yi, López-Moreno, José Juan, Marzari, F., Preusker, F., Scholten, F., Toth, I., and Tubiana, C.

Abstract

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.© 2019 The Author(s).

Published
2019

36. Towards a high-accuracy geological model of the 67P comet

Author

Franceschi, M., Penasa, L., Massironi, M., Ferrari, S., Naletto, G., Bertini, I., Cremonese, G., Ferri, F., Frattin, F., La Forgia, F., Lazzarin, M., Lucchetti, A., Marzari, F., Pajola, M., Simioni, E., Franceschi, M., Penasa, L., Massironi, M., Ferrari, S., Naletto, G., Bertini, I., Cremonese, G., Ferri, F., Frattin, F., La Forgia, F., Lazzarin, M., Lucchetti, A., Marzari, F., Pajola, M., and Simioni, E.

Abstract

It was recently shown that the layered structure of each of the two lobes of comet 67P/Churyumov-Gerasimenko (67P) can be modelled as a set of concentric ellipsoidal shells. The ellipsoidal model is able to correctly predict the major layering-related features on the comet surface; however, the ellipsoidal model is a first order approximation of a more complex internal structure. A better description of this latter requires an improved model. In this contribution preliminary results in building a refined three-dimensional model of the comet are presented with focus on the Small Lobe. The model is realized using a 3D geo-modeling technique that embeds linear and planar features (layer joints and terraces) as well as other geometric characteristics (e.g. vectorial fields) as constraints, influencing the reconstruction of the comet layered structure. Results allow accounting for features that are not predicted by the ellipsoidal model, therefore such refined 3D model is a step towards a model of the comet nucleus that may clues useful in unraveling the complex history that shaped it to its present configuration.

Published
2017

37. Quantitative analysis of isolated boulder fields on comet 67P/Churyumov-Gerasimenko

Author

Cambianica, P., primary, Cremonese, G., additional, Naletto, G., additional, Lucchetti, A., additional, Pajola, M., additional, Penasa, L., additional, Simioni, E., additional, Massironi, M., additional, Ferrari, S., additional, Bodewits, D., additional, La Forgia, F., additional, Sierks, H., additional, Lamy, P. L., additional, Rodrigo, R., additional, Koschny, D., additional, Davidsson, B., additional, Barucci, M. A., additional, Bertaux, J.-L., additional, Bertini, I., additional, Da Deppo, V., additional, Debei, S., additional, De Cecco, M., additional, Deller, J., additional, Fornasier, S., additional, Fulle, M., additional, Gutiérrez, P. J., additional, Güttler, C., additional, Ip, W.-H., additional, Keller, H. U., additional, Lara, L. M., additional, Lazzarin, M., additional, Lin, Z.-Y., additional, López-Moreno, J. J., additional, Marzari, F., additional, Mottola, S., additional, Shi, X., additional, Scholten, F., additional, Toth, I., additional, Tubiana, C., additional, and Vincent, J.-B., additional

Published
2019
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38. Rosetta/OSIRIS observations of the 67P nucleus during the April 2016 flyby: high-resolution spectrophotometry

Author

Feller, C., primary, Fornasier, S., additional, Ferrari, S., additional, Hasselmann, P. H., additional, Barucci, A., additional, Massironi, M., additional, Deshapriya, J. D. P., additional, Sierks, H., additional, Naletto, G., additional, Lamy, P. L., additional, Rodrigo, R., additional, Koschny, D., additional, Davidsson, B. J. R., additional, Bertaux, J.-L., additional, Bertini, I., additional, Bodewits, D., additional, Cremonese, G., additional, Da Deppo, V., additional, Debei, S., additional, De Cecco, M., additional, Fulle, M., additional, Gutiérrez, P. J., additional, Güttler, C., additional, Ip, W.-H., additional, Keller, H. U., additional, Lara, L. M., additional, Lazzarin, M., additional, López-Moreno, J. J., additional, Marzari, F., additional, Shi, X., additional, Tubiana, C., additional, Gaskell, B., additional, La Forgia, F., additional, Lucchetti, A., additional, Mottola, S., additional, Pajola, M., additional, Preusker, F., additional, and Scholten, F., additional

Published
2019
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39. Spectrophotometric variegation of the layering in comet 67P/Churyumov-Gerasimenko as seen by OSIRIS

Author

Tognon, G., primary, Ferrari, S., additional, Penasa, L., additional, La Forgia, F., additional, Massironi, M., additional, Naletto, G., additional, Lazzarin, M., additional, Cambianica, P., additional, Lucchetti, A., additional, Pajola, M., additional, Ferri, F., additional, Güttler, C., additional, Davidsson, B., additional, Deshapriya, P., additional, Fornasier, S., additional, Mottola, S., additional, Tóth, I., additional, Sierks, H., additional, Lamy, P. L., additional, Rodrigo, R., additional, Koschny, D., additional, Barbieri, C., additional, Barucci, M. A., additional, Bertaux, J.-L., additional, Bertini, I., additional, Bodewits, D., additional, Cremonese, G., additional, Da Deppo, V., additional, Debei, S., additional, De Cecco, M., additional, Deller, J., additional, Franceschi, M., additional, Frattin, E., additional, Fulle, M., additional, Gutiérrez, P. J., additional, Ip, W.-H., additional, Keller, H. U., additional, Lara, L. M., additional, López-Moreno, J. J., additional, Marzari, F., additional, Petropoulou, V., additional, Shi, X., additional, and Tubiana, C., additional

Published
2019
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40. Diurnal variation of dust and gas production in comet 67P/Churyumov-Gerasimenko at the inbound equinox as seen by OSIRIS and VIRTIS-M on board Rosetta

Author

Tubiana, C., primary, Rinaldi, G., additional, Güttler, C., additional, Snodgrass, C., additional, Shi, X., additional, Hu, X., additional, Marschall, R., additional, Fulle, M., additional, Bockelée-Morvan, D., additional, Naletto, G., additional, Capaccioni, F., additional, Sierks, H., additional, Arnold, G., additional, Barucci, M. A., additional, Bertaux, J.-L., additional, Bertini, I., additional, Bodewits, D., additional, Capria, M. T., additional, Ciarniello, M., additional, Cremonese, G., additional, Crovisier, J., additional, Da Deppo, V., additional, Debei, S., additional, De Cecco, M., additional, Deller, J., additional, De Sanctis, M. C., additional, Davidsson, B., additional, Doose, L., additional, Erard, S., additional, Filacchione, G., additional, Fink, U., additional, Formisano, M., additional, Fornasier, S., additional, Gutiérrez, P. J., additional, Ip, W.-H., additional, Ivanovski, S., additional, Kappel, D., additional, Keller, H. U., additional, Kolokolova, L., additional, Koschny, D., additional, Krueger, H., additional, La Forgia, F., additional, Lamy, P. L., additional, Lara, L. M., additional, Lazzarin, M., additional, Levasseur-Regourd, A. C., additional, Lin, Z.-Y., additional, Longobardo, A., additional, López-Moreno, J. J., additional, Marzari, F., additional, Migliorini, A., additional, Mottola, S., additional, Rodrigo, R., additional, Taylor, F., additional, Toth, I., additional, and Zakharov, V., additional

Published
2019
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41. Linking surface morphology, composition, and activity on the nucleus of 67P/Churyumov-Gerasimenko

Author

Fornasier, S., primary, Hoang, V. H., additional, Hasselmann, P. H., additional, Feller, C., additional, Barucci, M. A., additional, Deshapriya, J. D. P., additional, Sierks, H., additional, Naletto, G., additional, Lamy, P. L., additional, Rodrigo, R., additional, Koschny, D., additional, Davidsson, B., additional, Agarwal, J., additional, Barbieri, C., additional, Bertaux, J.-L., additional, Bertini, I., additional, Bodewits, D., additional, Cremonese, G., additional, Da Deppo, V., additional, Debei, S., additional, De Cecco, M., additional, Deller, J., additional, Ferrari, S., additional, Fulle, M., additional, Gutierrez, P. J., additional, Güttler, C., additional, Ip, W.-H., additional, Keller, H. U., additional, Küppers, M., additional, La Forgia, F., additional, Lara, M. L., additional, Lazzarin, M., additional, Lin, Z-Y, additional, Lopez Moreno, J. J., additional, Marzari, F., additional, Mottola, S., additional, Pajola, M., additional, Shi, X., additional, Toth, I., additional, and Tubiana, C., additional

Published
2019
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42. Multidisciplinary analysis of the Hapi region located on Comet 67P/Churyumov–Gerasimenko

Author

Pajola, M, primary, Lee, J-C, additional, Oklay, N, additional, Hviid, S F, additional, Penasa, L, additional, Mottola, S, additional, Shi, X, additional, Fornasier, S, additional, Davidsson, B, additional, Giacomini, L, additional, Lucchetti, A, additional, Massironi, M, additional, Vincent, J B, additional, Bertini, I, additional, Naletto, G, additional, Ip, W H, additional, Sierks, H, additional, Lamy, P L, additional, Rodrigo, R, additional, Koschny, D, additional, Keller, H U, additional, Agarwal, J, additional, Barucci, M A, additional, Bertaux, J L, additional, Bodewits, D, additional, Cambianica, P, additional, Cremonese, G, additional, Da Deppo, V, additional, Debei, S, additional, De Cecco, M, additional, Deller, J, additional, El Maarry, M R, additional, Feller, C, additional, Ferrari, S, additional, Fulle, M, additional, Gutierrez, P J, additional, Güttler, C, additional, Lara, L M, additional, La Forgia, F, additional, Lazzarin, M, additional, Lin, Z-Y, additional, Lopez Moreno, J J, additional, Marzari, F, additional, Preusker, F, additional, Scholten, F, additional, Toth, I, additional, and Tubiana, C, additional

Published
2019
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43. Experimental phase function and degree of linear polarization of cometary dust analogues

Author

Frattin, E, primary, Muñoz, O, additional, Moreno, F, additional, Nava, J, additional, Escobar-Cerezo, J, additional, Gomez Martin, J C, additional, Guirado, D, additional, Cellino, A, additional, Coll, P, additional, Raulin, F, additional, Bertini, I, additional, Cremonese, G, additional, Lazzarin, M, additional, Naletto, G, additional, and La Forgia, F, additional

Published
2019
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44. The phase function and density of the dust observed at comet 67P/Churyumov-Gerasimenko

Author

Fulle, Marco, Bertini, I., Della Corte, V., Guttler, C., Ivanovski, S., La Forgia, F., Lasue, J., Levasseur-Regourd, A. C., Marzari, F., Moreno, F., Mottola, S., Naletto, G., Palumbo, P., Rinaldi, G., Rotundi, A., Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Barucci, M. A., Bertaux, J. -L, Bodewits, D., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Groussin, O., Gutierrez, P. J., Hviid, H. S., Ip, W. H., Jorda, L., Keller, H. U., Knollenberg, J., Kramm, J. R., Kuhrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Lopez-Moreno, J. J., Shi, X., Thomas, N., Tubiana, C., Fulle, Marco, Bertini, I., Della Corte, V., Guttler, C., Ivanovski, S., La Forgia, F., Lasue, J., Levasseur-Regourd, A. C., Marzari, F., Moreno, F., Mottola, S., Naletto, G., Palumbo, P., Rinaldi, G., Rotundi, A., Sierks, H., Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Barucci, M. A., Bertaux, J. -L, Bodewits, D., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Groussin, O., Gutierrez, P. J., Hviid, H. S., Ip, W. H., Jorda, L., Keller, H. U., Knollenberg, J., Kramm, J. R., Kuhrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Lopez-Moreno, J. J., Shi, X., Thomas, N., and Tubiana, C.

Abstract

The OSIRIS camera onboard Rosetta measured the phase function of both the coma dust and the nucleus. The two functions have a very different slope versus the phase angle. Here, we show that the nucleus phase function should be adopted to convert the brightness to the size of dust particles larger than 2.5 mm only. This makes the dust bursts observed close to Rosetta by OSIRIS, occurring about every hour, consistent with the fragmentation on impact with Rosetta of parent particles, whose flux agrees with the dust flux observed by GIADA. OSIRIS also measured the antisunward acceleration of the fragments, thus providing the first direct measurement of the solar radiation force acting on the dust fragments and thus of their bulk density, excluding any measurable rocket effect by the ice sublimation from the dust. The obtained particle density distribution has a peak matching the bulk density of most COSIMA particles, and represents a subset of the density distribution measured by GIADA. This implies a bias in the elemental abundances measured by COSIMA, which thus are consistent with the 67P dust mass fractions inferred by GIADA, i.e. (38 +/- 8) per cent of hydrocarbons versus the (62 +/- 8) per cent of sulphides and silicates.

Published
2018
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45. The big lobe of 67P/Churyumov-Gerasimenko comet: Morphological and spectrophotometric evidences of layering as from OSIRIS data

Author

German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Ferrari, S., Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Fornasier, S., Hasselmann, P.H., Lucchetti, A., Pajola, M., Ferri, F., Cambianica, P., Oklay, N., Tubiana, C., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, E., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kührt, E., Küppers, M., Lara, Luisa María, López-Moreno, José Juan, Marzari, F., Shi, X., Simioni, E., Thomas, N., Vincent, J.B., German Centre for Air and Space Travel, Centre National D'Etudes Spatiales (France), Agenzia Spaziale Italiana, Agencia Estatal de Investigación (España), European Space Agency, Swedish National Space Agency, Ferrari, S., Penasa, L., La Forgia, F., Massironi, M., Naletto, G., Lazzarin, M., Fornasier, S., Hasselmann, P.H., Lucchetti, A., Pajola, M., Ferri, F., Cambianica, P., Oklay, N., Tubiana, C., Sierks, H., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Davidsson, B., Barucci, M.A., Bertaux, J.L., Bertini, I., Bodewits, D., Cremonese, G., Da Deppo, Vania, Debei, S., De Cecco, M., Deller, J., Franceschi, M., Frattin, E., Fulle, M., Groussin, O., Gutiérrez, Pedro J., Güttler, C., Hviid, S.F., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kührt, E., Küppers, M., Lara, Luisa María, López-Moreno, José Juan, Marzari, F., Shi, X., Simioni, E., Thomas, N., and Vincent, J.B.

Abstract

Between 2014 and 2016, ESA's Rosetta OSIRIS cameras acquired multiple-filters images of the layered nucleus of comet 67P/Churyumov-Gerasimenko, ranging from ultraviolet to near-infrared wavelengths. No correlation between layers disposition and surface spectral variegation has been observed so far. This paper investigates possible spectral differences among decametre-thickness outcropping layers of the biggest lobe of the comet by means of OSIRIS image dataset. A two-classes maximum likelihood classification was applied on consolidated outcrops and relative deposits identified on post-perihelion multispectral images of the big lobe. We distinguished multispectral data on the basis of the structural elevation of the onion-shell Ellipsoidal Model of 67P. The spatial distribution of the two classes displays a clear dependence on the structural elevation, with the innermost class resulting over 50 per cent brighter than the outermost one. Consolidated cometarymaterials located at different structural levels are characterized by different brightness and revealed due to the selective removal of large volumes. This variegation can be attributed to a different texture of the outcrop surface and/or to a different content of refractory materials.© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

Published
2018

46. The phase function and density of the dust observed at comet 67P/Churyumov-Gerasimenko

Author

Agenzia Spaziale Italiana, Fulle, M., Bertini, I., Della Corte, V., Güttler, C., Ivanovski, S., La Forgia, F., Lasue, J., Levasseur-Regourd, A. C., Marzari, F., Moreno, Fernando, Mottola, S., Naletto, G., Palumbo, P., Rinaldi, G., Rotundi, A., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Barucci, M.A., Bertaux, J.L., Bodewits, D., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Groussin, O., Gutiérrez, Pedro J., Hviid, H.S., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Shi, X., Thomas, N., Tubiana, C., Agenzia Spaziale Italiana, Fulle, M., Bertini, I., Della Corte, V., Güttler, C., Ivanovski, S., La Forgia, F., Lasue, J., Levasseur-Regourd, A. C., Marzari, F., Moreno, Fernando, Mottola, S., Naletto, G., Palumbo, P., Rinaldi, G., Rotundi, A., Sierks, H., Barbieri, C., Lamy, P.L., Rodrigo Montero, Rafael, Koschny, D., Rickman, H., Barucci, M.A., Bertaux, J.L., Bodewits, D., Cremonese, G., Da Deppo, Vania, Davidsson, B., Debei, S., De Cecco, M., Deller, J., Fornasier, S., Groussin, O., Gutiérrez, Pedro J., Hviid, H.S., Ip, W. H., Jorda, L., Keller, H.U., Knollenberg, J., Kramm, J.R., Kührt, E., Küppers, M., Lara, Luisa María, Lazzarin, M., López-Moreno, José Juan, Shi, X., Thomas, N., and Tubiana, C.

Abstract

The OSIRIS camera onboard Rosetta measured the phase function of both the coma dust and the nucleus. The two functions have a very different slope versus the phase angle. Here, we show that the nucleus phase function should be adopted to convert the brightness to the size of dust particles larger than 2.5 mm only. This makes the dust bursts observed close to Rosetta by OSIRIS, occurring about every hour, consistent with the fragmentation on impact with Rosetta of parent particles, whose flux agrees with the dust flux observed by GIADA. OSIRIS also measured the antisunward acceleration of the fragments, thus providing the first direct measurement of the solar radiation force acting on the dust fragments and thus of their bulk density, excluding any measurable rocket effect by the ice sublimation from the dust. The obtained particle density distribution has a peak matching the bulk density of most COSIMA particles, and represents a subset of the density distribution measured by GIADA. This implies a bias in the elemental abundances measured by COSIMA, which thus are consistent with the 67P dust mass fractions inferred by GIADA, i.e. (38 ± 8) per cent of hydrocarbons versus the (62 ± 8) per cent of sulphides and silicates.© 2018 The Author(s).Published by Oxford University Press on behalf of the Royal Astronomical Society.

Published
2018

48. SURFACE GEOLOGY OF 67P BY ROSETTA

Author

Massironi, M., Penasa, L., Ferrari, S., Simioni, E., La Forgia, F., Giacomini, L., Lee, J. C., Luchetti, A., Pajola, M., Naletto, G., Lazzarin, M, Cremonese, G, Bertini, I., Deppo, Da, Ferri, F., Marzari, F, Barbieri, C., and Sierks, H.

Published
2017

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