The dust environment of comet 67P/Churyumov-Gerasimenko from Rosetta OSIRIS/GIADA and VLT observations in the 4.5 to 2.9 AU heliocentric distance range inbound - Archive ouverte HAL Access content directly
Journal Articles Astronomy and Astrophysics - A&A Year : 2016

## The dust environment of comet 67P/Churyumov-Gerasimenko from Rosetta OSIRIS/GIADA and VLT observations in the 4.5 to 2.9 AU heliocentric distance range inbound

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F. Moreno
• Function : Author
Colin Snodgrass
Olivier Hainaut
• Function : Author
Cécilia Tubiana
• Function : Author
Holger Sierks
• Function : Author
Cesare Barbieri
Philippe L. Lamy
• Function : Author
Detlef Koschny
• Function : Author
Hans Rickman
• Function : Author
Jessica Agarwal
• Function : Author
Jean-Loup Bertaux
• Function : Author
• PersonId : 914210
Sebastien Besse
• Function : Author
Dennis Bodewits
• Function : Author
Gabriele Cremonese
• Function : Author
Vania da Deppo
Björn Davidsson
• Function : Author
S. Debei
• Function : Author
M. de Cecco
• Function : Author
Marco Fulle
• Function : Author
Olivier Groussin
• Function : Author
• PersonId : 837612
Pedro J. Gutiérrez
• Function : Author
• PersonId : 880386
Pablo Gutierrez-Marques
• Function : Author
Carsten Guttler
• Function : Author
Stubbe F. Hviid
• Function : Author
W.-H. Ip
• Function : Author
L. Jorda
Jörg Knollenberg
• Function : Author
Gabor Kovacs
• Function : Author
J.-Rainer Kramm
• Function : Author
Ekkehard Kührt
• Function : Author
Michael Küppers
L. M. Lara
• Function : Author
Monica Lazzarin
• Function : Author
José-Juan López-Moreno
• Function : Author
Stefano Mottola
• Function : Author
Giampiero Naletto
Nilda Oklay
• Function : Author
• PersonId : 976656
Maurizio Pajola
Nicholas Thomas
• Function : Author
Jean-Baptiste Vincent
• Function : Author
Vincenzo Della Corte
A. Fitzsimmons
• Function : Author
S. Faggi
• Function : Author
E. Jehin
Cyrielle Opitom
• Function : Author
G.-P. Tozzi
• Function : Author

#### Abstract

The ESA Rosetta spacecraft, currently orbiting around comet 67P, 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. 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. A Monte Carlo dust tail code 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. 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 $\alpha$=--3, instead of $\alpha$=--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.

### Dates and versions

insu-01274855 , version 1 (24-08-2020)

### Identifiers

• HAL Id : insu-01274855 , version 1
• ARXIV :
• BIBCODE :
• DOI :

### Cite

F. Moreno, Colin Snodgrass, Olivier Hainaut, Cécilia Tubiana, Holger Sierks, et al.. The dust environment of comet 67P/Churyumov-Gerasimenko from Rosetta OSIRIS/GIADA and VLT observations in the 4.5 to 2.9 AU heliocentric distance range inbound. Astronomy and Astrophysics - A&A, 2016, 587, A155 (12 p.). ⟨10.1051/0004-6361/201527564⟩. ⟨insu-01274855⟩

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