ﻻ يوجد ملخص باللغة العربية
We have analysed the ISO-SWS spectrum of Jupiter in the 12-16 micron range, where several hydrocarbons exhibit rovibrational bands. Using temperature information from the methane and hydrogen emissions, we derive the mixing ratios (q) of acetylene and ethane at two independent pressure levels. For acetylene, we find $q=(8.9^{+1.1}_{-0.6})times10^{-7}$ at 0.3 mbar and $q=(1.1^{+0.2}_{-0.1})times10^{-7}$ at 4 mbar, giving a slope $-dln q / dln P=0.8pm0.1$, while for ethane $q=(1.0pm0.2)times10^{-5}$ at 1 mbar and $q=(2.6^{+0.5}_{-0.6})times10^{-6}$ at 10 mbar, giving $-dln q / dln P=0.6pm0.2$. The ethane slope is consistent with the predictions of Gladstone et al. (1996), but that predicted for acetylene is larger than we observe. This disagreement is best explained by an overestimation of the acetylene production rate compared to that of ethane in the Gladstone et al. (1996) model. At 15.8 micron, methylacetylene is detected for the first time at low jovian latitudes, and a stratospheric column density of $(1.5pm0.4)times10^{15}$ molecule.cm-2 is inferred. We also derive an upper limit for the diacetylene column density of $7times10^{13}$ molecule.cm-2.
Oxygen atom addition and insertion reactions may provide a pathway to chemical complexity in ices that are too cold for radicals to diffuse and react. We have studied the ice-phase reactions of photo-produced oxygen atoms with C2 hydrocarbons under I
Infrared spectroscopy is a powerful tool to probe the inventory of solid state and molecular species in circumstellar ejecta. Here we analyse the infrared spectrum of the Asymptotic Giant Branch star W Hya, obtained by the Short and Long Wavelength S
The flybys of Jupiter by the Voyager spacecraft in 1979, and over two decades later by Cassini in 2000, have provided us with unique datasets from two different epochs, allowing the investigation of seasonal change in the atmosphere. In this paper we
A detailed spectroscopic study of the ISO-SWS data of the red giant Alpha Tau is presented, which enables not only the accurate determination of the stellar parameters of Alpha Tau, but also serves as a critical review of the ISO-SWS calibration. T
We present new ISO-SWS data for a sample of 27 starburst galaxies, and with these data examine the issues of formation and evolution of the most massive stars in starburst galaxies. Using starburst models which incorporate time evolution, new stellar