BepiColombo observations of cold oxygen and carbon ions in the flank of the induced magnetosphere of Venus

L Z Hadid (1) , Dominique Delcourt (1, 2) , Y Saito (3) , M Fränz (4) , S Yokota (5) , B Fiethe (6) , C Verdeil (7) , B Katra (1) , François Leblanc (8) , H Fischer (4) , M Persson (7, 9) , S Aizawa (1) , N André (7) , Y Harada (10) , A Fedorov (7) , D Fontaine (1) , N Krupp (4) , H Michalik (6) , Jean-Jacques Berthelier (8) , H Krüger (4) , G Murakami (3) , S Matsuda (11) , D Heyner (12) , H-U Auster (12) , I Richter (12) , J Z D Mieth (12) , D Schmid (13) , D Fischer (13)

1 LPP - Laboratoire de Physique des Plasmas
2 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
3 ISAS - Institute of Space and Astronautical Science
4 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
5 Osaka University [Osaka]
6 IDA - Institute of Computer and Network Engineering [Braunschweig]
7 IRAP - Institut de recherche en astrophysique et planétologie
8 HELIOS - LATMOS
9 Graduate School of Frontier Sciences [Kashiwa]
10 Kyoto University
11 Graduate School of the Natural Science and Technology [Kanazawa]
12 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
13 IWF - Space Research Institute of Austrian Academy of Sciences

On 10 August 2021, the Mercury-bound BepiColombo spacecraft performed its second y-by of Venus and provided a short-lived observation of its induced magnetosphere. Here we report results recorded by the Mass Spectrum Analyzer on board Mio, which reveal the presence of cold O+ and C+ with an average total ux of ~4 ± 1 × 104 cm−2 s−1 at a distance of about six planetary radii in a region that has never been explored before. The ratio of escaping C+ to O+ is at most 0.31 ± 0.2, implying that, in addition to atomic O+ ions, CO group ions or water group ions may be a source of the observed O+. Simultaneous magnetometer observations suggest that these planetary ions were in the magnetosheath ank in the vicinity of the magnetic pileup boundary downstream. These results have important implications regarding the evolution of Venus’s atmosphere and, in particular, the evolution of water on the surface of the planet.

Domaines: Planète et Univers [physics]

L Z Hadid, Dominique Delcourt, Y Saito, M Fränz, S Yokota, et al.. BepiColombo observations of cold oxygen and carbon ions in the flank of the induced magnetosphere of Venus. Nature Astronomy, 2024, 8, pp.716-724. ⟨10.1038/s41550-024-02247-2⟩. ⟨insu-04546379v2⟩