J. Lecacheux

A study of the 3ν3CH4 region in a high-resolution spectrum of Jupiter recorded by Fourier transform spectroscopy

Abstract A spectrum of Jupiter between 6000 and 12 000 cm − at high resolution (0.05 cm − ) was recorded with a Michelson interferometer at Palomar Mountain in October 1974. An analysis of the R branch of the 3 ν 3 CH 4 band with the reflecting-layer model, taking into account the H 2 absorption which occurs in the same spectral range, leads to a Lorentzian half-width of 0.09 ± 0.02 cm −1 , a rotational temperature of 175 ± 10° K, and a CH 4 abundance of order 52m atm. Five lines of the 13 CH 4 3ν 3 band have been identified; a comparison with new laboratory spectra indicates that the 13 CH 4 / 12 CH 4 ratio in the Jupiter atmosphere is close to the terrestrial ratio.

Behavior of Titan's atmosphere during a total eclipse

Abstract The edge-on presentation of Saturns rings and satellites system has provided a rare opportunity to observe total eclipses of Titan. During its emersion from the Saturnian shadow (1980, June 28), Titan has been observed simultaneously in the visible and the infrared ranges (6000–9000 A, 11.8 μm and 20 μm). No change has been recorded in these three spectral ranges. Our observations tend to support the thick-atmosphere model, which has been shown to be valid by Voyager a few months later.