Revised tholin profile for the atmosphere of Titan Mao-Chang Liang 1, J. A. Kammer, X. Zhang 3, D. Shemansky 4, Y. L. Yung 2 1 Research Center for Environmental Change, Academia Sinica 2 Division of Geological and Planetary Sciences, California Institute of Technology 3 University of Arizona 4 Space Environment Technologies
Stellar occulations Aerosol extinction profiles Tb Vi, Tb Sco, T21 Eri, T41 CMa (ingress & egress), T47 Uma Solar occulation T0 Scattering spectrum at 1040 km Cassini UVIS
Lorenz + Mitton 2002
Solar Scattering Stellar Occultation J. Ajello
T0 olar reflection spectrum High resolution slit; Integration time sec; Red line: Effective altitude 1040 km; mid pixel 1203 km Green line: Effective altitude 1612 km Cyan line: best fitting model spectrum
T0 UVIS extinction spectrum Liang et al tholin CH 4 Impact: 514 km
UVIS extinction profiles
Modeling – No production/loss g cm A ~10 -3 g cm -3 eddy g cm g cm -3
Solution #1 – C 2 H 2 -> tholin g cm -2 3 g cm -2 size increase 76 A -> 3300 A
Extinction coefficient Particle radius (A)
Fractal particles Aggregate of molecules at ~1000 km monomer: 10 A Mie radius: 76 A density: ~10 -3 g cm -3 -> fractal dimension: ~1.5 Main haze (<300 km) monomer: 66 nm fractional dimension: 2
Low density fractal particle ~10 -3 g cm -3 abve ~800 km Particle size of 76 A at 1040 km Increase to ~3300 A below ~500 km, compared to 660 A monomer size below 300 km Mass flux from the top is ~ g cm -2 No net production between km Summary