The dust environment of comet 67P/Churyumov-Gerasimenko from Rosetta OSIRIS and VLT observations in the 4.5 to 2.9 AU heliocentric distance range inbound
comets: individual: 67P/Churyumov-Gerasimenko; methods: data analysis; techniques: photometric
Abstract :
[en] Context. The ESA Rosetta spacecraft, currently orbiting around comet 67P/Churyumov-Gerasimenko, has already provided in situ measurements of the dust grain properties from several instruments,particularly OSIRIS and GIADA. We propose adding value to those measurements by combining them with ground-based observations of the dust tail to monitor the overall, time-dependent dust-production rate and size distribution. <BR /> Aims: To constrain the dust grain properties, we take Rosetta OSIRIS and GIADA results into account, and combine OSIRIS data during the approach phase (from late April to early June 2014) with a large data set of ground-based images that were acquired with the ESO Very Large Telescope (VLT) from February to November 2014. <BR /> Methods: A Monte Carlo dust tail code, which has already been used to characterise the dust environments of several comets and active asteroids, has been applied to retrieve the dust parameters. Key properties of the grains (density, velocity, and size distribution) were obtained from Rosetta observations: these parameters were used as input of the code to considerably reduce the number of free parameters. In this way, the overall dust mass-loss rate and its dependence on the heliocentric distance could be obtained accurately. <BR /> Results: The dust parameters derived from the inner coma measurements by OSIRIS and GIADA and from distant imaging using VLT data are consistent, except for the power index of the size-distribution function, which is α = -3, instead of α = -2, for grains smaller than 1 mm. This is possibly linked to the presence of fluffy aggregates in the coma. The onset of cometary activity occurs at approximately 4.3 AU, with a dust production rate of 0.5 kg/s, increasing up to 15 kg/s at 2.9 AU. This implies a dust-to-gas mass ratio varying between 3.8 and 6.5 for the best-fit model when combined with water-production rates from the MIRO experiment.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Moreno, F.; Instituto de Astrofísica de Andalucía, , CSIC, Glorieta de la Astronomía s/n, 18008, Granada, Spain
Snodgrass, C.; Planetary and Space Sciences, Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, Buckinghamshire, MK7 6AA, UK
Hainaut, O.; European Southern Observatory, Karl-Schwarschild-Strasse 2, 85748, Garching bei München, Germany
Barbieri, C.; Department of Physics and Astronomy G. Galilei, University of Padova, Vic. Osservatorio 3, 35122, Padova, Italy ; Center of Studies and Activities for Space (CISAS) G. Colombo, University of Padova, via Venezia 15, 35131, Padova, Italy
Lamy, Philippe L.; Aix Marseille Université, CNRS, LAM (Laboratoire dAstro-physique de Marseille) UMR 7326, 13388, Marseille, France
Rodrigo, R.; Centro de Astrobiologia (INTA-CSIC), European Space Agency (ESA), European Space Astronomy Centre (ESAC), PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain ; International Space Science Institute, Hallerstrasse 6, 3012, Bern, Switzerland
Koschny, D.; Research and Scientific Support Department, European Space Agency, 2201, Noordwijk, The Netherlands
Rickman, H.; PAS Space Research Center, Bartycka 18A, 00716, Warszawa, Poland ; Department of Physics and Astronomy, Uppsala University, Box 516, 75120, Uppsala, Sweden
Keller, H. U.; Institute for Geophysics and Extraterrestrial Physics, TU Braunschweig, 38106, Braunschweig, Germany
Kührt, E.; Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstrasse 2, 12489, Berlin, Germany
Küppers, M.; ESA/ESAC, PO Box 78, 28691, Villanueva de la Cañada, Spain
Lara, L. M.; Instituto de Astrofísica de Andalucía, , CSIC, Glorieta de la Astronomía s/n, 18008, Granada, Spain
Lazzarin, M.; Department of Physics and Astronomy G. Galilei, University of Padova, Vic. Osservatorio 3, 35122, Padova, Italy
López-Moreno, J. J.; Instituto de Astrofísica de Andalucía, , CSIC, Glorieta de la Astronomía s/n, 18008, Granada, Spain
Marzari, F.; Department of Physics and Astronomy G. Galilei, University of Padova, Vic. Osservatorio 3, 35122, Padova, Italy
Mottola, S.; Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstrasse 2, 12489, Berlin, Germany
Naletto, G.; Center of Studies and Activities for Space (CISAS) G. Colombo, University of Padova, via Venezia 15, 35131, Padova, Italy ; CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131, Padova, Italy ; Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131, Padova, Italy
Pajola, M.; Center of Studies and Activities for Space (CISAS) G. Colombo, University of Padova, via Venezia 15, 35131, Padova, Italy
Thomas, N.; Physikalisches Institut, Sidlerstrasse 5, University of Bern, 3012, Bern, Switzerland
Vincent, J. B.; Max-Planck Institut für Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077, Göttingen, Germany
Della Corte, V.; Institute for Space Astrophysics and Planetology (IAPS), National Institute for AstroPhysics (INAF), via Fosso del Cavaliere 100, 00133, Roma, Italy
Fitzsimmons, A.; Astrophysics Research Centre, School of Physics and Astronomy, Queen's University Belfast, Belfast, BT7 1NN, UK
Faggi, S.; INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50 125, Firenze, Italy
Jehin, Emmanuel ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Opitom, Cyrielle ; Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Origines Cosmologiques et Astrophysiques (OrCa)
Tozzi, G.-P.; INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50 125, Firenze, Italy)
The dust environment of comet 67P/Churyumov-Gerasimenko from Rosetta OSIRIS and VLT observations in the 4.5 to 2.9 AU heliocentric distance range inbound
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