Cold Dense Ion Outflow Observed in the Martian-Induced Magnetotail by MAVEN

S. Inui , K. Seki , T. Namekawa , S. Sakai , D. A. Brain , T. Hara , J. P. Mcfadden , J. S. Halekas , D. L. Mitchell , C. Mazelle (1) , G. A. Dibraccio , B. M. Jakosky

1 IRAP - Institut de recherche en astrophysique et planétologie

Cold ion outflow is one of the candidate processes to cause significant atmospheric escape from Mars. We here report on the cold dense heavy ion outflow event observed in Martian-induced magnetotail by Mars Atmosphere and Volatile EvolutioN (MAVEN) on 4 December 2014. In the outflow event, the cold dense heavy ion outflow was observed only in south dusk downward convection electric field (E) lobe. During the event, the strong crustal magnetic field was located on dayside of Mars. It suggests that combination of minimagnetosphere and downward E facilitates the cold dense heavy ion outflow. In order to estimate the CO₂⁺ density, we adopted a fitting method of log-normal distribution to the O₂⁺ time of flight distributions to eliminate O₂⁺ contamination in the CO₂⁺ time of flight data. Contribution of O₂⁺, O⁺, and CO₂⁺ to the total heavy ions ( 134 cm^-3) is about 71%, 26%, and 3%, respectively. Average heavy ion flux was 5.4 × 10⁷ cm^-2s^-1, assuming the escape velocity at 2,000-km altitude.

Mots clés: Mars; atmospheric escape; carbon dioxide; MAVEN

Domaines: Planète et Univers [physics]

S. Inui, K. Seki, T. Namekawa, S. Sakai, D. A. Brain, et al.. Cold Dense Ion Outflow Observed in the Martian-Induced Magnetotail by MAVEN. Geophysical Research Letters, 2018, 45, pp.5283-5289. ⟨10.1029/2018GL077584⟩. ⟨insu-03678199⟩