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We report on high-resolution and spatially-resolved spectra of Io in the 4.0 {mu}m region, recorded with the VLT/CRIRES instrument in 2008 and 2010, which provide the first detection of the { u}1 + { u}3 band of SO2 in Ios atmosphere. Data are analyzed to constrain the latitudinal, longitudinal, and diurnal distribution of Ios SO2 atmosphere as well as its characteristic temperature. equatorial SO2 column densities clearly show longitudinal asymmetry, but with a maximum of around 1.5e17 cm-2 at central meridian longitude L = 200-220 and a minimum of around 3e16 cm-2 at L = 285-300, the longitudinal pattern somewhat differs from earlier inferences from Ly {alpha} and thermal IR measurements. Within the accuracy of the measurements, no evolution of the atmospheric density from mid-2008 to mid-2010 can be distinguished. The decrease of the SO2 column density towards high latitude is apparent, and the typical latitudinal extent of the atmosphere found to be (+-) 40{deg} at half-maximum. The data show moderate diurnal variations of the equatorial atmosphere, which is evidence for a partially sublimation-supported atmospheric component. Compared to local noon, factor of 2 lower densities are observed around 40{deg} before and 80{deg} after noon. Best-fit gas temperatures range from 150 to 220 K, with a weighted mean value of 170 (+-) 20 K, which should represent the column-weighted mean kinetic temperature of Ios atmosphere. Finally, although the data include clear thermal emission due to Pillan (in outburst in July 2008) and Loki, no detectable enhancements in the SO2 atmosphere above these volcanic regions are found, with an upper limit of 4e16 cm-2 at Pillan and 1e17 cm-2 at Loki.
The goal is to determine the composition of Plutos atmosphere and to constrain the nature of surface-atmosphere interactions. We perform high--resolution spectroscopic observations in the 2.33--2.36 $mu$m range, using CRIRES at the VLT. We obtain
Context: Pluto possesses a thin atmosphere, primarily composed of nitrogen, in which the detection of methane has been reported. Aims: The goal is to constrain essential but so far unknown parameters of Plutos atmosphere such as the surface pressur
High-resolution transmission spectroscopy is a method for understanding the chemical and physical properties of upper exoplanetary atmospheres. Due to large absorption cross-sections, resonance lines of atomic sodium D-lines (at 5889.95 $AA$ and 5895
We report on higly accurate absolute frequency measurement against a femtosecond frequency comb of 6 saturated absorption lines of formic acid (HCOOH) with an accuracy of 1 kHz. We also report the frequency measurement of 17 other lines with an accur