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Start Over Author "Masoumzadeh, N." Publisher univ bern, phys inst, sidlerstr 5, ch-3012 bern, switzerland.
10 results on '"Masoumzadeh, N."'

1. Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta

Author

Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., Tubiana, C., Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., and Tubiana, C.

Abstract

Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance R-h = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this paper was that through the sublimation of the aggregates of dirty grains (radius a between 5 and 50 mu m) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data, we needed to inject a number of aggregates between 8.5 x 10(13) and 8.5 x 10(10) for a = 5 and 50 mu m, respectively, or an initial mass of H2O ice around 22 kg.

Published
2016
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2. Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Author

Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., Vincent, J. -B, Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., and Vincent, J. -B

Abstract

We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the Optical, Spectroscopic and Infrared Remote Imaging System instrument during the closest fly-by over the comet, which took place on 2015 February 14 at a distance of similar to 6 km from the surface. Several images covering the 0 degrees-33 degrees. phase angle range were acquired, and the spatial resolution achieved was 11 cm pixel(-1). The flown-by region is located on the big lobe of the comet, near the borders of the Ash, Apis and Imhotep regions. Our analysis shows that this region features local heterogeneities at the decimetre scale. We observed difference of reflectance up to 40 per cent between bright spots and sombre regions, and spectral slope variations up to 50 per cent. The spectral reddening effect observed globally on the comet surface by Fornasier et al. (2015) is also observed locally on this region, but with a less steep behaviour. We note that numerous metre-sized boulders, which exhibit a smaller opposition effect, also appear spectrally redder than their surroundings. In this region, we found no evidence linking observed bright spots to exposed water-ice-rich material. We fitted our data set using the Hapke 2008 photometric model. The region overflown is globally as dark as the whole nucleus (geometric albedo of 6.8 per cent) and it has a high porosity value in the uppermost layers (86 per cent). These results of the photometric analysis at a decimetre scale indicate that the photometric properties of the flown-by region are similar to those previously found for the whole nucleus.

Published
2016
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3. Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta

Author

Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., Tubiana, C., Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., and Tubiana, C.

Abstract

Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance R-h = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this paper was that through the sublimation of the aggregates of dirty grains (radius a between 5 and 50 mu m) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data, we needed to inject a number of aggregates between 8.5 x 10(13) and 8.5 x 10(10) for a = 5 and 50 mu m, respectively, or an initial mass of H2O ice around 22 kg.

Published
2016
Full Text
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4. Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta

Author

Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., Tubiana, C., Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., and Tubiana, C.

Abstract

Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance R-h = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this paper was that through the sublimation of the aggregates of dirty grains (radius a between 5 and 50 mu m) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data, we needed to inject a number of aggregates between 8.5 x 10(13) and 8.5 x 10(10) for a = 5 and 50 mu m, respectively, or an initial mass of H2O ice around 22 kg.

Published
2016
Full Text
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5. Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Author

Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., Vincent, J. -B, Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., and Vincent, J. -B

Abstract

We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the Optical, Spectroscopic and Infrared Remote Imaging System instrument during the closest fly-by over the comet, which took place on 2015 February 14 at a distance of similar to 6 km from the surface. Several images covering the 0 degrees-33 degrees. phase angle range were acquired, and the spatial resolution achieved was 11 cm pixel(-1). The flown-by region is located on the big lobe of the comet, near the borders of the Ash, Apis and Imhotep regions. Our analysis shows that this region features local heterogeneities at the decimetre scale. We observed difference of reflectance up to 40 per cent between bright spots and sombre regions, and spectral slope variations up to 50 per cent. The spectral reddening effect observed globally on the comet surface by Fornasier et al. (2015) is also observed locally on this region, but with a less steep behaviour. We note that numerous metre-sized boulders, which exhibit a smaller opposition effect, also appear spectrally redder than their surroundings. In this region, we found no evidence linking observed bright spots to exposed water-ice-rich material. We fitted our data set using the Hapke 2008 photometric model. The region overflown is globally as dark as the whole nucleus (geometric albedo of 6.8 per cent) and it has a high porosity value in the uppermost layers (86 per cent). These results of the photometric analysis at a decimetre scale indicate that the photometric properties of the flown-by region are similar to those previously found for the whole nucleus.

Published
2016
Full Text
View/download PDF

6. Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Author

Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., Vincent, J. -B, Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., and Vincent, J. -B

Abstract

We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the Optical, Spectroscopic and Infrared Remote Imaging System instrument during the closest fly-by over the comet, which took place on 2015 February 14 at a distance of similar to 6 km from the surface. Several images covering the 0 degrees-33 degrees. phase angle range were acquired, and the spatial resolution achieved was 11 cm pixel(-1). The flown-by region is located on the big lobe of the comet, near the borders of the Ash, Apis and Imhotep regions. Our analysis shows that this region features local heterogeneities at the decimetre scale. We observed difference of reflectance up to 40 per cent between bright spots and sombre regions, and spectral slope variations up to 50 per cent. The spectral reddening effect observed globally on the comet surface by Fornasier et al. (2015) is also observed locally on this region, but with a less steep behaviour. We note that numerous metre-sized boulders, which exhibit a smaller opposition effect, also appear spectrally redder than their surroundings. In this region, we found no evidence linking observed bright spots to exposed water-ice-rich material. We fitted our data set using the Hapke 2008 photometric model. The region overflown is globally as dark as the whole nucleus (geometric albedo of 6.8 per cent) and it has a high porosity value in the uppermost layers (86 per cent). These results of the photometric analysis at a decimetre scale indicate that the photometric properties of the flown-by region are similar to those previously found for the whole nucleus.

Published
2016
Full Text
View/download PDF

7. Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta

Author

Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., Tubiana, C., Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., and Tubiana, C.

Abstract

Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance R-h = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this paper was that through the sublimation of the aggregates of dirty grains (radius a between 5 and 50 mu m) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data, we needed to inject a number of aggregates between 8.5 x 10(13) and 8.5 x 10(10) for a = 5 and 50 mu m, respectively, or an initial mass of H2O ice around 22 kg.

Published
2016
Full Text
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8. Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Author

Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., Vincent, J. -B, Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., and Vincent, J. -B

Abstract

We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the Optical, Spectroscopic and Infrared Remote Imaging System instrument during the closest fly-by over the comet, which took place on 2015 February 14 at a distance of similar to 6 km from the surface. Several images covering the 0 degrees-33 degrees. phase angle range were acquired, and the spatial resolution achieved was 11 cm pixel(-1). The flown-by region is located on the big lobe of the comet, near the borders of the Ash, Apis and Imhotep regions. Our analysis shows that this region features local heterogeneities at the decimetre scale. We observed difference of reflectance up to 40 per cent between bright spots and sombre regions, and spectral slope variations up to 50 per cent. The spectral reddening effect observed globally on the comet surface by Fornasier et al. (2015) is also observed locally on this region, but with a less steep behaviour. We note that numerous metre-sized boulders, which exhibit a smaller opposition effect, also appear spectrally redder than their surroundings. In this region, we found no evidence linking observed bright spots to exposed water-ice-rich material. We fitted our data set using the Hapke 2008 photometric model. The region overflown is globally as dark as the whole nucleus (geometric albedo of 6.8 per cent) and it has a high porosity value in the uppermost layers (86 per cent). These results of the photometric analysis at a decimetre scale indicate that the photometric properties of the flown-by region are similar to those previously found for the whole nucleus.

Published
2016
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9. Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations

Author

Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., Vincent, J. -B, Feller, C., Fornasier, S., Hasselmann, P. H., Barucci, A., Preusker, F., Scholten, F., Jorda, L., Pommerol, A., Jost, B., Poch, O., ElMaary, M. R., Thomas, N., Belskaya, I., Pajola, M., Sierks, H., Barbieri, C., Lamy, P. L., Koschny, D., Rickman, Hans, Rodrigo, R., Agarwal, J., A'Hearn, M., Bertaux, J. -L, Bertini, I., Boudreault, S., Cremonese, G., Da Deppo, V., Davidsson, B. J. R., Debei, S., De Cecco, M., Deller, J., Fulle, M., Giquel, A., Groussin, O., Gutierrez, P. J., Guettler, C., Hofmann, M., Hviid, S. F., Keller, H., Ip, W. -H, Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kuppers, M., Lara, M. L., Lazzarin, M., Leyrat, C., Moreno, J. J. Lopez, Marzari, F., Masoumzadeh, N., Mottola, S., Naletto, G., Perna, D., Oklay, N., Shi, X., Tubiana, C., and Vincent, J. -B

Abstract

We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the Optical, Spectroscopic and Infrared Remote Imaging System instrument during the closest fly-by over the comet, which took place on 2015 February 14 at a distance of similar to 6 km from the surface. Several images covering the 0 degrees-33 degrees. phase angle range were acquired, and the spatial resolution achieved was 11 cm pixel(-1). The flown-by region is located on the big lobe of the comet, near the borders of the Ash, Apis and Imhotep regions. Our analysis shows that this region features local heterogeneities at the decimetre scale. We observed difference of reflectance up to 40 per cent between bright spots and sombre regions, and spectral slope variations up to 50 per cent. The spectral reddening effect observed globally on the comet surface by Fornasier et al. (2015) is also observed locally on this region, but with a less steep behaviour. We note that numerous metre-sized boulders, which exhibit a smaller opposition effect, also appear spectrally redder than their surroundings. In this region, we found no evidence linking observed bright spots to exposed water-ice-rich material. We fitted our data set using the Hapke 2008 photometric model. The region overflown is globally as dark as the whole nucleus (geometric albedo of 6.8 per cent) and it has a high porosity value in the uppermost layers (86 per cent). These results of the photometric analysis at a decimetre scale indicate that the photometric properties of the flown-by region are similar to those previously found for the whole nucleus.

Published
2016
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10. Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta

Author

Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., Tubiana, C., Gicquel, A., Vincent, J. -B, Agarwal, J., A'Hearn, M. F., Bertini, I., Bodewits, D., Sierks, H., Li, Z. -Y, Barbieri, C., Lamy, P. L., Rodrigo, R., Koschny, D., Rickman, Hans, Keller, H. U., Barucci, M. A., Bertaux, J. -L, Besse, S., Cremonese, G., Da Deppo, V., Davidsson, Björn, Debei, S., Deller, J., De Cecco, M., Frattin, E., El-Maarry, M. R., Fornasier, S., Fulle, M., Groussin, O., Gutierrez, P. J., Gutierrez-Marquez, P., Guettler, C., Hoefner, S., Hofmann, M., Hu, X., Hviid, S. F., Ip, W. -H, Jorda, L., Knollenberg, J., Kovacs, G., Kramm, J. -R, Kuehrt, E., Kueppers, M., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Lowry, S., Marzari, F., Masoumzadeh, N., Massironi, M., Moreno, F., Mottola, S., Naletto, G., Oklay, N., Pajola, M., Pommerol, A., Preusker, F., Scholten, F., Shi, X., Thomas, N., Toth, I., and Tubiana, C.

Abstract

Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance R-h = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this paper was that through the sublimation of the aggregates of dirty grains (radius a between 5 and 50 mu m) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data, we needed to inject a number of aggregates between 8.5 x 10(13) and 8.5 x 10(10) for a = 5 and 50 mu m, respectively, or an initial mass of H2O ice around 22 kg.

Published
2016
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