On the amount of heavy molecular ions in Titan's ionosphere

J. E. Wahlund; M. Galand; I. Müller-Wodarg; J. Cui; R. V. Yelle; F. J. Crary; K. Mandt; B. Magee; J. H. Waite; D. T. Young; A. J. Coates; P. Garnier; K. Ågren; M. André; A. I. Eriksson; T. E. Cravens; V. Vuitton; D. A. Gurnett; W. S. Kurth

doi:10.1016/j.pss.2009.07.014

On the amount of heavy molecular ions in Titan's ionosphere

J. E. Wahlund, M. Galand, I. Müller-Wodarg, J. Cui, R. V. Yelle, F. J. Crary, K. Mandt, B. Magee, J. H. Waite, D. T. Young, A. J. Coates, P. Garnier, K. Ågren, M. André, A. I. Eriksson, T. E. Cravens, V. Vuitton, D. A. Gurnett, W. S. Kurth

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73 Scopus citations

Abstract

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 ~10⁵-10⁶ heavy positively charged ions/m³/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.

Original language	English (US)
Pages (from-to)	1857-1865
Number of pages	9
Journal	Planetary and Space Science
Volume	57
Issue number	14-15
DOIs	https://doi.org/10.1016/j.pss.2009.07.014
State	Published - Dec 2009

Keywords

Aerosol formation
Cassini
Heavy molecular ions
Ionospheric physics
Titan aeronomy
Titan's ionosphere

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1016/j.pss.2009.07.014

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Wahlund, J. E., Galand, M., Müller-Wodarg, I., Cui, J., Yelle, R. V., Crary, F. J., Mandt, K., Magee, B., Waite, J. H., Young, D. T., Coates, A. J., Garnier, P., Ågren, K., André, M., Eriksson, A. I., Cravens, T. E., Vuitton, V., Gurnett, D. A., & Kurth, W. S. (2009). On the amount of heavy molecular ions in Titan's ionosphere. Planetary and Space Science, 57(14-15), 1857-1865. https://doi.org/10.1016/j.pss.2009.07.014

Wahlund, JE, Galand, M, Müller-Wodarg, I, Cui, J, Yelle, RV, Crary, FJ, Mandt, K, Magee, B, Waite, JH, Young, DT, Coates, AJ, Garnier, P, Ågren, K, André, M, Eriksson, AI, Cravens, TE, Vuitton, V, Gurnett, DA & Kurth, WS 2009, 'On the amount of heavy molecular ions in Titan's ionosphere', Planetary and Space Science, vol. 57, no. 14-15, pp. 1857-1865. https://doi.org/10.1016/j.pss.2009.07.014

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abstract = "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 ~105-106 heavy positively charged ions/m3/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.",

keywords = "Aerosol formation, Cassini, Heavy molecular ions, Ionospheric physics, Titan aeronomy, Titan's ionosphere",

author = "Wahlund, {J. E.} and M. Galand and I. M{\"u}ller-Wodarg and J. Cui and Yelle, {R. V.} and Crary, {F. J.} and K. Mandt and B. Magee and Waite, {J. H.} and Young, {D. T.} and Coates, {A. J.} and P. Garnier and K. {\AA}gren and M. Andr{\'e} and Eriksson, {A. I.} and Cravens, {T. E.} and V. Vuitton and Gurnett, {D. A.} and Kurth, {W. S.}",

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T1 - On the amount of heavy molecular ions in Titan's ionosphere

AU - Wahlund, J. E.

AU - Galand, M.

AU - Müller-Wodarg, I.

AU - Cui, J.

AU - Yelle, R. V.

AU - Crary, F. J.

AU - Mandt, K.

AU - Magee, B.

AU - Waite, J. H.

AU - Young, D. T.

AU - Coates, A. J.

AU - Garnier, P.

AU - Ågren, K.

AU - André, M.

AU - Eriksson, A. I.

AU - Cravens, T. E.

AU - Vuitton, V.

AU - Gurnett, D. A.

AU - Kurth, W. S.

PY - 2009/12

Y1 - 2009/12

N2 - 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 ~105-106 heavy positively charged ions/m3/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.

AB - 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 ~105-106 heavy positively charged ions/m3/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.

KW - Aerosol formation

KW - Cassini

KW - Heavy molecular ions

KW - Ionospheric physics

KW - Titan aeronomy

KW - Titan's ionosphere

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JO - Planetary and Space Science

JF - Planetary and Space Science

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ER -

On the amount of heavy molecular ions in Titan's ionosphere

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Keywords

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