Search Publications
Abundant ammonium hydrosulphide embedded in cometary dust grains
Altwegg, K.; Fuselier, S. A.; Rubin, M. +7 more
Ammonium hydrosulphide has long since been postulated to exist at least in certain layers of the giant planets. Its radiation products may be the reason for the red colour seen on Jupiter. Several ammonium salts, the products of NH3, and an acid have previously been detected at comet 67P/Churyumov-Gerasimenko. The acid H2S is…
Macro and micro structures of pebble-made cometary nuclei reconciled by seasonal evolution
Longobardo, Andrea; Mottola, Stefano; Kappel, David +17 more
Comets evolve due to sublimation of ices embedded inside porous dust, triggering dust emission (that is, erosion) followed by mass loss, mass redistribution and surface modifications. Surface changes were revealed by the Deep Impact and Stardust NExT missions for comet 9P/Tempel 1 (ref. 1), and a full inventory of the processes modifyin…
High D/H ratios in water and alkanes in comet 67P/Churyumov-Gerasimenko measured with Rosetta/ROSINA DFMS
Altwegg, K.; Berthelier, J. J.; Fuselier, S. A. +8 more
Context. Isotopic abundances in comets are key to understanding and reconstructing the history and origin of material in the Solar System. Data for deuterium-to-hydrogen (D/H) ratios in water are available for several comets. However, no long-term studies of the D/H ratio in water of a comet during its passage around the Sun have been reported thu…
Modelling the water and carbon dioxide production rates of Comet 67P/Churyumov-Gerasimenko
Samarasinha, Nalin H.; Farnocchia, Davide; Gutiérrez, Pedro J. +1 more
The European Space Agency Rosetta/Philae mission to Comet 67P/Churyumov-Gerasimenko in 2014-2016 is the most complete and diverse investigation of a comet carried out thus far. Yet, many physical and chemical properties of the comet remain uncertain or unknown, and cometary activity is still not a well-understood phenomenon. We here attempt to pla…
Effects of Grain Alignment with Magnetic Fields on Grain Growth and the Structure of Dust Aggregates
Hoang, Thiem
Dust grains drift through the interstellar medium and are aligned with the magnetic field. Here we study the effect of grain alignment and motion on grain growth in molecular clouds (MCs). We first discuss the characteristic timescales of alignment of the grain axis of maximum inertia ( $\hat{{\boldsymbol{a}}}$ 1) with its angular momen…
Identification and characterization of a new ensemble of cometary organic molecules
Altwegg, K.; Fuselier, S. A.; Rubin, M. +4 more
In-situ study of comet 1P/Halley during its 1986 apparition revealed a surprising abundance of organic coma species. It remained unclear, whether or not these species originated from polymeric matter. Now, high-resolution mass-spectrometric data collected at comet 67P/Churyumov-Gerasimenko by ESA's Rosetta mission unveil the chemical structure of …
Formation of Comets
Blum, Jürgen; Gundlach, Bastian; Bischoff, Dorothea
Questions regarding how primordial or pristine the comets of the solar system are have been an ongoing controversy. In this review, we describe comets' physical evolution from dust and ice grains in the solar nebula to the contemporary small bodies in the outer solar system. This includes the phases of dust agglomeration, the formation of planetes…
Successive deuteration in low-mass star-forming regions: The case of D2-methanol (CHD2OH) in IRAS 16293-2422
Margulès, Laurent; Drozdovskaya, Maria N.; Jørgensen, Jes K. +3 more
Context. Di-deuterated molecules are observed in the earliest stages of star formation at abundances of a few percent relative to their nondeuterated isotopologs, which is unexpected considering the scarcity of deuterium in the interstellar medium. With sensitive observations leading to the detection of a steadily increasing number of di-deuterate…
The Plasma Environment of Comet 67P/Churyumov-Gerasimenko
Henri, Pierre; Feldman, Paul D.; Simon Wedlund, Cyril +24 more
The environment of a comet is a fascinating and unique laboratory to study plasma processes and the formation of structures such as shocks and discontinuities from electron scales to ion scales and above. The European Space Agency's Rosetta mission collected data for more than two years, from the rendezvous with comet 67P/Churyumov-Gerasimenko in …
Geodesy of irregular small bodies via neural density fields
Izzo, Dario; Gómez, Pablo
Asteroids' and comets' geodesy is a challenging yet important task for planetary science and spacecraft operations, such as ESA's Hera mission tasked to look at the aftermath of the recent NASA DART spacecraft's impact on Dimorphos. Here we present a machine learning approach based on so-called geodesyNets which learns accurate density models of i…