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The dust coma environment of 67P/Churyumov-Gerasimenko as observed by VIRTIS

Rinaldi, G. and Bockelee-Morvan, D. and Ciarniello, M. and Tozzi, G. and Fink, U. and Doose, L. and Capaccioni, F. and Della Corte, Vincenzo and Fulle, M. and Rotundi, A. and Filacchione, G. and Taylor, F.W. and Kappel, David and Erard, S. and Leyrat, C. and Raponi, A. and D'Aversa, E. and Ivanovski, S. and Capria, M. T. and Longobardo, A and Palomba, E. and Tosi, F. and Migliorini, A. and Salatti, M. (2018) The dust coma environment of 67P/Churyumov-Gerasimenko as observed by VIRTIS. In: Cospar 2018, 42nd Assembly, Scientific Assembly Abstracts, pp. 226-227. 42nd COSPAR Scientific Assembly 2018, 14.-22. Jul. 2018, Pasadena, CA, USA.

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Official URL: http://cospar2018.org/wp-content/uploads/2018/07/COSPAR-2018-Abstract-Book_July21-2018-UPDATE.pdf


ESA's Rosetta spacecraft had the unique opportunity to be in the vicinity of comet 67P/Churyumov-Gerasimenko for 2.5 years, observing the regions of the coma within a few km of the surface and to study the dynamical and physical properties of the emitted dust. In this work, we will present a summary of the dust coma investigations during the pre-perihelion and the perihelion passage, performed by the Visible InfraRed Thermal Imaging Spectrometer (VIRTIS) onboard Rosetta, in the spectral range between 0.2 to 5 _m (Coradini et al. 2007). During the pre-perihelion period, the main dust results can be summarized as follows: 1-The general spatial distribution of the dust is strongly correlated with the presence of H2O emission and is significantly different from the distribution of CO2 emission; 2-The sunward radial profiles of the dust show that the dust particles, lifted off the nucleus, are accelerated by the gas in the first 4-5 km and then transit into the free flowing collision-less zone with a 1/_ column density profile, where _ is the distance from the center of the comet; 4- The colour of the dust in the coma has a fairly steep red slope in the VIS of about 9 to 12 ± 1 % per 100 nm and a much shallower slope in the IR with values of 1.7 ± 0.2 % per 100 nm. The colours do not show any spatial variation, nor any variation with distance from the nucleus. This indicates that the dust expelled into the coma from the nucleus is quite uniform, although it could also be that any changes in its composition (Rinaldi et al. 2016). 5- Combining the VIRTIS data with those by GIADA, the dust detector onboard Rosetta, we evaluate the dust size distribution power-law index that is greater than -3.1. This index matches the one determined using GIADA (Della Corte et al. 2016) March 2015 data indicating that the inner coma radiance is dominated by particles larger than 10 _m (Rinaldi et al. 2017).During the perihelion period, we focused on the analysis of the outburst events. The outbursts are characterized by a sudden and short increase of the dust emission, from localized areas with variable degree of collimation, followed by a gradual decrease of activity with a life time ranging between 6 to 24 minutes. The quick onset is correlated with a change of the visible dust colour from redder with 15-18 ± 3 %/100 nm, to bluer with values around 7-10 ± 0.3%/100 nm (Rinaldi et al. 2018, in preparation). The combination of VIS and IR dust properties reveals the presence of very small (less than 100 nm) and bright grains in the ejecta that could be formed by silicate material, implying the thermal degradation of the carbonaceous material, or icy grains (Bockelée-Morvan et al 2017). The dust coma from the outburst was found to expand at speeds between 22.2 ±2.2 to 30.2 ± 1.4 m/s for the "big" outbursts and 38.4 ± 2.1 to 64.9 ±10.6 m/s for "mini" ones. The total ejected mass during an outburst event is estimated to lie between 100 to 6000 kg for a duration of 6 - 24 minutes, assuming a size distribution indexes between -2.5 to -3 (Rinaldi et al. 2018, in preparation).References:Rinaldi G., et al., 2016, MNRAS, 462, S547. Rinaldi G., et al., 2017, MNRAS 469S, 598R. Bockelée-Morvan D., et al., 2017, MNRAS, 469, S443. Rinaldi G., et al., 2018, in preparation. Coradini A., et al., 2007, Space Sci. Rev., 128, 529. Della Corte V., et al., 2016, Acta Astronautica, 126, 205

Item URL in elib:https://elib.dlr.de/124749/
Document Type:Conference or Workshop Item (Speech)
Title:The dust coma environment of 67P/Churyumov-Gerasimenko as observed by VIRTIS
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Rinaldi, G.Istituto di Fisica dello Spazio Interplanetario (IFSI-INAF), Rome - ItalyUNSPECIFIED
Bockelee-Morvan, D.Observatoire de Paris, MeudonUNSPECIFIED
Tozzi, G.Osservatorio Astrofisico di Arcetri, Firenze, ItalyUNSPECIFIED
Fink, U.Lunar Planetary Laboratory, Univarsity of Arizona, Tucson, USAUNSPECIFIED
Doose, L.University of ArizonaUNSPECIFIED
Della Corte, VincenzoINAF-IAPS, Roma, ItalyUNSPECIFIED
Fulle, M.INAF - Osservatorio Astronomico di Trieste, Trieste, ItalyUNSPECIFIED
Rotundi, A.University of Naples, Naples, ItalyUNSPECIFIED
Filacchione, G.INAF-IASF, Rome, ItalyUNSPECIFIED
Taylor, F.W.University of OxfordUNSPECIFIED
Kappel, DavidDavid.Kappel (at) dlr.deUNSPECIFIED
Ivanovski, S.Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica (INAF), Via Fosso del Cavaliere, 100, 0133 Rome, ItalyUNSPECIFIED
Capria, M. T.Instituto di Astrofisica Spaziale e Fisica Cosmica, Roma, ItalyUNSPECIFIED
Longobardo, AINAF-LAPS, Via del Fosso del Cavaliere 100, I-00133 Rome, ItalyUNSPECIFIED
Palomba, E.Institute for Interplanetary Space Physics - INAF, Rome, ItalyUNSPECIFIED
Tosi, F.INAF-IASF Istituto di Astrofisica Spaziale e Fisica Cosmica, Roma ItalyUNSPECIFIED
Date:17 July 2018
Journal or Publication Title:Cospar 2018, 42nd Assembly, Scientific Assembly Abstracts
Refereed publication:No
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Page Range:pp. 226-227
Keywords:Comet 67P, Coma, Dust, VIRTIS
Event Title:42nd COSPAR Scientific Assembly 2018
Event Location:Pasadena, CA, USA
Event Type:international Conference
Event Dates:14.-22. Jul. 2018
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project ROSETTA Instruments
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Leitungsbereich PF
Deposited By: Kappel, David
Deposited On:11 Dec 2018 09:28
Last Modified:11 Dec 2018 09:28

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