Article Dans Une Revue Astronomy & Astrophysics - A&A Année : 2026

Seasonal variation of the main gases in Titan's ionosphere from Cassini INMS data

Résumé

With 13 years of observations, the Ion and Neutral Mass Spectrometer (INMS) on board the Cassini spacecraft has observed the upper atmosphere of Titan through two seasons: northern winter and spring. The complex atmosphere is mainly composed of N 2 , CH 4 , H 2 , and Ar, but many other carbon and nitrogen bearing trace species have been observed by INMS and other instruments. Using data from the closed source neutral (CSN) mode of the INMS instrument, we studied the abundance of the main gases and their variation in Titan's ionosphere between 1500 and 950 km of altitude with a new mass spectra deconvolution code based on a Monte Carlo approach. Our results showed a hemispheric dichotomy in gas mole fractions at a constant altitude, with an enrichment of methane mole fraction in the southern hemisphere that seems to decreases after 2011 during northern spring. At constant N 2 density, however, regardless of the hemisphere, we observe an increase in the N 2 mole fraction with time. We note a strong correlation between the gas mole fraction and the solar cycle as well. We also derived an 14 N/ 15 N isotope ratio of 197.7 ± 3.9(3σ).

Fichier principal
Vignette du fichier
aa48044-23.pdf (1022.91 Ko) Télécharger le fichier
Origine Fichiers éditeurs autorisés sur une archive ouverte
Licence

Dates et versions

hal-05595333 , version 1 (17-04-2026)

Licence

Identifiants

Citer

Maélie Coutelier, Thomas Gautier, Koyena Das, Joseph Serigano, Joseph Westlake, et al.. Seasonal variation of the main gases in Titan's ionosphere from Cassini INMS data. Astronomy & Astrophysics - A&A, 2026, 708 (229), ⟨10.1051/0004-6361/202348044⟩. ⟨hal-05595333⟩
1 Consultations
0 Téléchargements

Altmetric

Partager

  • More