On the amount of heavy molecular ions in Titan's ionosphere
2009 (English)In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 57, no 14-15, 1857-1865 p.Article in journal (Refereed) Published
We present observational evidence that the ionosphere of Titan below an altitude of 1150 km is a significant source of heavy (> 100 amu) molecular organic species. This study is based on measurements by five instruments (RPWS/LP, RPWS/E, INMS, CAPS/ELS, CAPS/IBS) onboard the Cassini spacecraft during three flybys (T17, T18, T32) of Titan. The ionospheric peaks encountered at altitudes of 950-1300 km had densities in the range 900-3000 cm(-3). Below these peaks the number densities of heavy positively charged ions reached 100-2000 cm(-3) and approached 50-70% of the total ionospheric density with an increasing trend toward lowest measured altitudes. Simultaneously measured negatively charged ion densities were in the range 50-150 cm(-3). These results imply that similar to 10(5)similar to 10(6) heavy positively charged ions/m(3)/s are continuously recombining into heavy neutrals and supply the atmosphere of Titan. The ionosphere may in this way produce 0.1-1 Mt/yr of heavy organic compounds and is therefore a sizable source for aerosol formation. We also predict that Titan's ionosphere is dominated by heavy (> 100 amu) molecular ions below 950 km.
Place, publisher, year, edition, pages
2009. Vol. 57, no 14-15, 1857-1865 p.
Titan's ionosphere, Cassini, Heavy molecular ions, Titan aeronomy, Aerosol formation, Ionospheric physics
IdentifiersURN: urn:nbn:se:uu:diva-148205DOI: 10.1016/j.pss.2009.07.014ISI: 000273099100023OAI: oai:DiVA.org:uu-148205DiVA: diva2:401666