Open this publication in new window or tab >>LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, 92195 Meudon, France.
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France.
Department of Astronomy, University of California, 22 Berkeley, CA 94720, USA; Department of Earth and Planetary Science, University of California, 22 Berkeley, CA 94720, USA.
LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, 92195 Meudon, France.
LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, 92195 Meudon, France.
KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, 92195 Meudon, France.
Institute of Geophysics and Meteorology, University of Cologne, Albertus Magnus Platz, 50923 Cologne, Germany, Albertus Magnus Platz.
Institute of Geophysics and Meteorology, University of Cologne, Albertus Magnus Platz, 50923 Cologne, Germany, Albertus Magnus Platz.
LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS, 92195 Meudon, France.
University of Wisconsin, Madison, WI 53706, USA.
Department of Astronomy & Astrophysics, University of California, San Diego, La Jolla, CA 92093, USA, La Jolla.
Division of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125, USA.
Johns Hopkins University Applied Physics Laboratory, 11001 Johns Hopkins Rd, Laurel, MD 20723, USA, 11001 Johns Hopkins Rd.
Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands.
Division of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125, USA.
School of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK, University Road.
Division of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125, USA.
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France.
Istituto Nazionale di AstroFisica - Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), 00133 Rome, Italy.
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France.
Istituto Nazionale di AstroFisica - Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), 00133 Rome, Italy.
Department of Astronomy, University of California, 22 Berkeley, CA 94720, USA.
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2024 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 690, article id L11Article in journal (Refereed) Published
Abstract [en]
Jupiter's icy moon Ganymede has a tenuous exosphere produced by sputtering and possibly sublimation of water ice. To date, only atomic hydrogen and oxygen have been directly detected in this exosphere. Here, we present observations of Ganymede's CO2 exosphere obtained with the James Webb Space Telescope. CO2 gas is observed over different terrain types, mainly over those exposed to intense Jovian plasma irradiation, as well as over some bright or dark terrains. Despite warm surface temperatures, the CO2 abundance over equatorial subsolar regions is low. CO2 vapor has the highest abundance over the north polar cap of the leading hemisphere, reaching a surface pressure of 1 pbar. From modeling we show that the local enhancement observed near 12 h local time in this region can be explained by the presence of cold traps enabling CO2 adsorption. However, whether the release mechanism in this high-latitude region is sputtering or sublimation remains unclear. The north polar cap of the leading hemisphere also has unique surface-ice properties, probably linked to the presence of the large atmospheric CO2 excess over this region. These CO2 molecules might have been initially released in the atmosphere after the radiolysis of CO2 precursors, or from the sputtering of CO2 embedded in the H2O ice bedrock. Dark terrains (regiones), more widespread on the north versus south polar regions, possibly harbor CO2 precursors. CO2 molecules would then be redistributed via cold trapping on ice-rich terrains of the polar cap and be diurnally released and redeposited on these terrains. Ganymede's CO2 exosphere highlights the complexity of surface-atmosphere interactions on Jupiter's icy Galilean moons.
Place, publisher, year, edition, pages
EDP Sciences, 2024
Keywords
Planets and satellites: atmospheres, Planets and satellites: composition, Planets and satellites: individual: Ganymede
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-355964 (URN)10.1051/0004-6361/202451599 (DOI)001336770600018 ()2-s2.0-85207449206 (Scopus ID)
Note
QC 20241111
2024-11-062024-11-062024-11-11Bibliographically approved