Search Publications
Prestellar grain-surface origins of deuterated methanol in comet 67P/Churyumov-Gerasimenko
De Keyser, Johan; van Dishoeck, Ewine F.; Drozdovskaya, Maria N. +6 more
Deuterated methanol is one of the most robust windows astrochemists have on the individual chemical reactions forming deuterium-bearing molecules and the physicochemical history of the regions where they reside. The first-time detection of mono- and di-deuterated methanol in a cometary coma is presented for comet 67P/Churyumov-Gerasimenko using Ro…
D/H in the refractory organics of comet 67P/Churyumov-Gerasimenko measured by Rosetta/COSIMA
Hilchenbach, M.; Merouane, S.; Engrand, C. +11 more
The D/H ratio is a clue to the origin and evolution of hydrogen-bearing chemical species in Solar system materials. D/H has been observed in the coma of many comets, but most such measurements have been for gaseous water. We present the first in situ measurements of the D/H ratios in the organic refractory component of cometary dust particles coll…
The effect of varying porosity and inhomogeneities of the surface dust layer on the modelling of comet gas production
Skorov, Yuri; Reshetnyk, Volodymyr; Blum, Jürgen +3 more
We study how uncertainties in knowledge of the microstructure of the porous dust surface layer affect our estimates of effective gas production of comet 67P/Churyumov-Gerasimenko. We analyse the transport properties (distribution of free paths, mean pore size, permeability) for random densely packed porous layers. Bimodal layers, as well as variou…
Modelling heterogeneous dust particles: an application to cometary polarization
Halder, Prithish; Ganesh, Shashikiran
In this work, we introduce a comet dust model that incorporates multiple dust morphologies along with inhomogeneous mixture of silicate minerals and carbonaceous materials under power-law size distribution, to replicate the standard polarization-phase curve observed in several comets in the narrow-band continuum. Following the results from Rosetta…
Water and deuterium-to-hydrogen ratio in comets
Fulle, Marco
Recent models find that nuclei of comets are a mixture of water-rich and water-poor cm-sized pebbles. We aim to fit the correlation of the deuterium-to-hydrogen ratio, D/H, with the nucleus active area fraction. Pebble parameters, constrained by the Rosetta mission data, depend on where pebbles accreted in the protoplanetary disc. The diversity of…
Surface roughness of asteroid (162173) Ryugu and comet 67P/Churyumov-Gerasimenko inferred from in situ observations
Jaumann, R.; Stephan, K.; Mottola, S. +28 more
Alteration processes on asteroid and comet surfaces, such as thermal fracturing, (micrometeorite) impacts or volatile outgassing, are complex mechanisms that form diverse surface morphologies and roughness on various scales. These mechanisms and their interaction may differ on the surfaces of different bodies. Asteroid Ryugu and comet 67P/Churyumo…
Ion bulk speeds and temperatures in the diamagnetic cavity of comet 67P from RPC-ICA measurements
Nilsson, Hans; Stenberg Wieser, Gabriella; Wieser, Martin +6 more
Comets are constantly interacting with the solar wind. When the comet activity is high enough, this leads to the creation of a magnetic field free region around the nucleus known as the diamagnetic cavity. It has been suggested that the ion-neutral drag force is balancing the magnetic pressure at the cavity boundary, but after the visit of Rosetta…
Remote sensing of cometary bow shocks: modelled asymmetric outgassing and pickup ion observations
Alho, Markku; Jarvinen, Riku; Simon Wedlund, Cyril +3 more
Despite the long escort by the ESA Rosetta mission, direct observations of a fully developed bow shock around 67P/Churyumov-Gerasimenko have not been reported. Expanding on our previous work on indirect observations of a shock, we model the large-scale features in cometary pickup ions, and compare the results with the ESA Rosetta Plasma Consortium…
Flow directions of low-energy ions in and around the diamagnetic cavity of comet 67P
Nilsson, Hans; Stenberg Wieser, Gabriella; Wieser, Martin +5 more
The flow direction of low-energy ions around comet 67P/Churyumov-Gerasimenko has previously been difficult to constrain due to the influence of the spacecraft potential. The Ion Composition Analyzer of the Rosetta Plasma Consortium (RPC-ICA) on Rosetta measured the distribution function of positive ions with energies down to just a few eV/q throug…
Observational constraints to the dynamics of dust particles in the coma of comet 67P/Churyumov-Gerasimenko
Sierks, H.; Fulle, M.; Güttler, C. +18 more
In this work, we aim to characterize the dust motion in the inner coma of comet 67P/Churyumov-Gerasimenko to provide constraints for theoretical 3D coma models. The OSIRIS camera on-board the Rosetta mission was able for the first time to acquire images of single dust particles from inside the cometary coma, very close to the nucleus. We analyse a…