Author/Authors :
Luz، نويسنده , , D. and Civeit، نويسنده , , T. and Courtin، نويسنده , , R. and Lebreton، نويسنده , , J.-P. and Gautier، نويسنده , , D. and Rannou، نويسنده , , P. and Kaufer، نويسنده , , A. and Witasse، نويسنده , , O. Anaya-Lara، نويسنده , , L. and Ferri De Collibus، نويسنده , , F.، نويسنده ,
Abstract :
Titan has been observed with UVES, the UV–Visual Echelle Spectrograph at the Very Large Telescope, with the aim of characterizing the zonal wind flow. We use a retrieval scheme originally developed for absolute stellar accelerometry [Connes, P., 1985. Astrophys. Space Sci., 110, 211–255] to extract the velocity signal by simultaneously taking into account all the lines present in the spectrum. The method allows to measure the Doppler shift induced at a given point by the zonal wind flow, with high precision. The short-wavelength channel (4200–5200 Å) probes one scale height higher than the long-wavelength one (5200–6200 Å), and we observe statistically significant evidence for stronger winds at higher altitudes. The results show a high dispersion. Globally, we detect prograde zonal winds, with lower limits of 62 and 50 m s−1 at the regions centered at 200 and 170 km altitude, but approximately a quarter of the measurements indicates null or retrograde winds.
