Titan Airglow: FUV & EUV 2009 UVIS Spectra of Airglow During Day, Night & Eclipse : JOSEPH AJELLO JPL MICHAEL STEVENS NRL ROBERT WEST JACQUES GUSTIN LPAP GREG HOLSCLAW CU TODD BRADLEY UCF Team meeting: Jan20112

TITAN PROTON PLASMA (0.1 keV-4 MeV) & SOLAR XUV GENERATES 2-level IONOSPHERE (300-1500 KM) Solar XUV Excitation –Strong Top Ionosphere -Magnetospheric: p and O+ Plasma Sporadic low ionosphere (Cravens et al., 2008). S. Pol South SS. POLE shelf

N2 Cross section Analysis for Dayglow VI (2)→UVIS (16)→Lab(e +N2 300 features) V(z)=g(z) x w AURIC MODEL gj (z) = F (e) x n(z) x s(e)   Dl=0.2Å Dl=30Å Dl=5Å DD

ISS & UVIS OBSERVATION OF TITAN SOLAR ECLIPSE @ 600K km UV- VIS-near IR (200-1200) nm N2 night glow to 1000 km plasma + N2

FUV T53 DARK SIDE RECORD 0 LIMB & DISK SPECTRA DOY110-2009 @15K km (MRH = SURFACE-800 KM) polar

T53 EUV DARK SIDE RECORD 1 LIMB & DISK SPECTRA DOY110-2009 @15K km -Spectrum =Eclipse at 20 x closer -4-minute records -Record 0 MRH = surface to 800 km -Record 1;MRH = 800-1100 KM) -NO Rayleigh scattering Plasma excitation : 500-1200 km -Molecular bands and NI ,II lines -1/10 Intensity of Dayglow

Laboratory Result: p + N2

ELECTRON CROSS SECTIONS FOR TITAN DAYGLOW UV EMISSION MODEL Stevens et al., 2011 “Production of Titan’s Far ions Ultraviolet Nitrogen Airglow” AURIC Code Emission Cross Sections: N2 Carroll-Yoshino c4′—X system,b‘-X, b-X systems N I and N II multiplets the N2 Lyman-Birge-Hopfield a—X system (Young et al., 2010) the N2 Vegard-Kaplan A—X bands sLBH=0.7 A&S (1985)

Pixel Center Ray Height (km) Best (S/N) Titan Dayglow UVIS Limb Spectrum; 22June 2009: ‘800 km STARE’ Stevens et al., 2011 –40 One hour EUV and FUV image of 15 – 4 minute records . –42 EUV –44 DEC (deg) –46 –48 4 2 –2 –4 RA (deg) 1500 1000 FUV Pixel Center Ray Height (km) 500 10 20 30 40 50 60 Pixel Number

AURIC MODEL FIT TO UVIS EUV SPECTRUM AT 1000 KM

AURIC MODEL FIT TO UVIS FUV SPECTRUM AT 1000 KM

AURIC MODEL OF FUV VERs AND COLUMN EMISSION RATES

The FUV Dayglow Limb Spectra of Titan Tb Tangential Scan Surface to Exosphere: 13Dec04.

DARK SIDE OBSERVATION OF TITAN ON 25MARCH2008

FUV LIMB PROFILE INTENSITIES OF 25 MARCH2009

Model fit to UVIS Dark Limb (Twilight) EUV Spectrum from 25Mar08 with a Regression Model - 7-Vectors)

How to get a BRIGHT UV Airglow in 2009 BRIGHTEST LIMB AIRGLOW 22JUNE 2009 obs[14] SZA=53DEG, MRH =1000 km S/C ~60k KM BRIGHTEST DISK & 2ND LIMB 12OCT OBS[45-51] LIMB~ 1000KM SZA~95, S/C ~175k KM

2009 Observations from Lower Ionosphere Dark Limb (F0,F5) to Topside Bright Limb (F9, F14, F48)

SUMMARY OF 2009 ECLIPSE, LIMB, BRIGHT DISK AND DARK DISK UVIS OBSERVATIONS OF TITAN Solar Driven processes on Dayside and Twilight Observed EUV and FUV Emissions during 1 of 3 Eclipses. Probably Plasma impact. Tentative Sporadic FUV Nightglow Spectra at 0.1 Intensity level of dayglow (500-1200 km). Probably Plasma Impact (protons, O+, electrons). Twilight (Terminator) Glow-Solar XUV at 90-120 deg Limb SZA ~ 0.2-0.5 Dayside Intensity. N2 EUV (12R) /FUV (200R) dayglow structure similar to Earth Extend Published/Modeled spectra from 800-1900 Å

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