Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Molecules in planetary atmospheres Emmanuel Lellouch Observatoire de Paris Some history… Kuiper 1944 « The only reason why I happened to observe the planets and the 10 brightest satellites was that they were nicely lined up in a region of the sky where I had run out of programs stars » Detection of methane in Titan Vertical profile of methane from Huygens and Cassini VIMS Some history… CO produced on dayside from CO2 + h CO Yet, more CO on Venus nightside than on dayside! Why hunt for molecules in planets? 1. Because we like to see new species and because planetary spectra can be beautiful CH3CN in Titan (IRAM 30-m; Marten et al. 2002) Why hunt for molecules in planets? (even in the infrared…) Detection of C6H6 in Saturn (ISO; Bézard et al. 2001) Disk resolved spectroscopy of Io : detection of S2 in the Pele plume and even in the UV… HST/STIS long-slit spectroscopy of Pele plume Spencer et al. 2000 Why hunt for molecules in planets? 2. Because it gives information on chemical pathways SATURN Detection of hydrogen peroxide (H2O2) on Mars •Production HO2 + HO2 H2O2 +O2 •Destruction H2O2 + h v 2 OH 362 GHz (JCMT) 8 µm (IRTF) Clancy et al. 2004 Encrenaz (THERESE) et al 2005 Why hunt for molecules in planets? 3. Because it gives information on dynamics and the couplings with chemistry CO lines give maps of - CO vertical profile - Thermal profile - Wind velocity VENUS Measuring mesospheric winds on Titan ~300 km ~450 km Moreno and Marten 2005 Why hunt for molecules in planets? 4. Because it gives information on the interactions between Solar System objects External water in the outer planets ODIN ISO • Interplanetary dust • Planetary environments • Cometary impacts HERSCHEL CO in Neptune’s atmosphere IRAM 30-m: 8x 1 GHz Discovery (JCMT) Marten et al. 1991 A dual source? - internal - comet impact Lellouch et al. 2005 Why hunt for molecules in planets? 4bis) Sometimes, it gives us incomprehensible problems! Evolution of the Shoemaker-Levy 9 debris on Jupiter CO, CS, HCN HCN • Chemical effect? • Dynamical effect? CO2 Why hunt for molecules in planets? 5. Because it is a way to study exotic atmospheres (and to make good friends…) SO2, SO, and NaCl in Io’s atmosphere (IRAM 30-m) SO2 Origin? • Volcanism • Sublimation equilibrium (not NaCl) Detection of NaCl in Io’s atmosphere Why hunt for molecules in planets? 6. Because it tells us things about origin and evolution of planets (sorry, this time, I will take a break about helium and deuterium) Isotopic ratios in Titan’s atmosphere 12C/13C SMA Gurwell 2004 = terrestrial 14N/15N in HCN = 4.5 times less than terrestrial in N2 (Cassini) = 1.5 times than terrestrial ESCAPE of Titan atmosphere + FRACTIONATION in HCN Why hunt for molecules in planets? 7. Because it is a race and we are ready to make big efforts for it CO on Pluto 4 days of good Weather Int. time 2090 min. Bockelee-Morvan et al. 2001 Stupid galactic contamination Search for new compounds on Venus from limbspectroscopy during the June 8 transit (T. Fouchet) OFF ON What do you think it happened? 1. The IRAM TAC did not give time 2. The observations had to be stopped quickly because the telescope started to heat dangerously 3. The observations were performed but nothing was detected (even the 50 % deep CO lines) 4. CO(2-1) only was detected 5. The observations led to the first detection of SO2 in Venus’ upper atmosphere What it happened 1. The IRAM TAC did not give time 2. The observations had to be stopped quickly because the telescope started to heat dangerously 3. The observations were performed but nothing was detected (even the 50 % deep CO lines) – 200 K ripples!! 4. CO(2-1) only was detected 5. The observations led to the first detection of SO2 in Venus’ upper atmosphere Detection of J2O on Earth (Cambridge 2005 DPS meeting) J2O abundance: 2 bpp* * bottles person per Why hunt for molecules in planets? 5. … or good enemies…