@article{RinaldiFormisanoKappeletal.2019, author = {Rinaldi, G. and Formisano, M. and Kappel, David and Capaccioni, F. and Bockelee-Morvan, D. and Cheng, Y-C and Vincent, J-B and Deshapriya, P. and Arnold, G. and Capria, M. T. and Ciarniello, M. and De Sanctis, M. C. and Doose, L. and Erard, S. and Federico, C. and Filacchione, G. and Fink, U. and Leyrat, C. and Longobardo, A. and Magni, G. and Mighorini, A. and Mottola, S. and Naletto, G. and Raponi, A. and Taylor, F. and Tosi, F. and Tozzi, G. P. and Salatti, M.}, title = {Analysis of night-side dust activity on comet 67P observed by VIRTIS-M}, series = {Astronomy and astrophysics : an international weekly journal}, volume = {630}, journal = {Astronomy and astrophysics : an international weekly journal}, publisher = {EDP Sciences}, address = {Les Ulis}, issn = {1432-0746}, doi = {10.1051/0004-6361/201834907}, pages = {16}, year = {2019}, abstract = {On 2015 July 18, near perihelion at a heliocentric distance of 1.28 au, the Visible InfraRed Thermal Imaging Spectrometer (VIRTIS-M) on board the Rosetta spacecraft had the opportunity of observing dust activity in the inner coma with a view of the night side (shadowed side) of comet 67P/Churyumov-Gerasimenko. At the time of the measurements we present here, we observe a dust plume that originates on the far side of the nucleus. We are able to identify the approximate location of its source at the boundary between the Hapi and Anuket regions, and we find that it has been in darkness for some hours before the observation. Assuming that this time span is equal to the conductive time scale, we obtain a thermal inertia in the range 25-36 W K-1 m(-2) s(-1/2). These thermal inertia values can be used to verify with a 3D finite-element method (REM) numerical code whether the surface and subsurface temperatures agree with the values found in the literature. We explored three different configurations: (1) a layer of water ice mixed with dust beneath a dust mantle of 5 mm with thermal inertia of 36 J m(-2) K-1 S-0.5 ; (2) the same structure, but with thermal inertia of 100 J m(-2) K-1 S-0.5; (3) an ice-dust mixture that is directly exposed. Of these three configurations, the first seems to be the most reasonable, both for the low thermal inertia and for the agreement with the surface and subsurface temperatures that have been found for the comet 67P/Churyumov-Gerasimenko. The spectral properties of the plume show that the visible dust color ranged from 16 +/- 4.8\%/100 nm to 13 +/- 2.6\%/100 nm, indicating that this plume has no detectable color gradient. The morphology of the plume can be classified as a narrow jet that has an estimated total ejected mass of between 6 and 19 tons when we assume size distribution indices between -2.5 and -3.}, language = {en} }