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The James Webb Space Telescope (JWST) is expected to be launched in 2021. The JWST’s science instruments will provide high quality spectra acquired in the line of sight to young stellar objects whose interpretation will require a robust database of laboratory data. With this in mind, an experimental work is in progress in the Laboratory for Experimental Astrophysics in Catania to study the profile (shape, width, and peak position) of the main infrared bands of molecular species expected to be present in icy grain mantles. Our study also takes into account the modifications induced on icy samples by low-energy cosmic ray bombardment and by thermal processing. Here we present some recent results on deuterium hydrogen monoxide (HDO), N-bearing species, and carbon dioxide (CO2).
The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?
In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.
The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.
EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.
For the first time the kinetic rate constants of the UV photolysis of polyynes C6H2, C8H2, C10H2, C12H2 and C14H2 under rigorously inert atmosphere have been determined in three different solvents: n-hexane, n-heptane and decalin. First- or pseudofirst-order kinetics appear suitable to describe the photolysis of these molecules and k values in the range between 3.0×10−3 s−1 and 4.6×10−3 s−1 have been determined. The unique exception is represented by C6H2 which photolyses more slowly with k=3.2×10−4 s−1. Two different UV sources have been used in the present study: a low-pressure mercury lamp having a monochromatic emission at 253.7 nm and a medium-to high-pressure lamp with a continuous emission between 222 nm and 580 nm. The results are of interest in the understanding, and also the modelling, of the fate of polyynes released by carbon-rich stars in the interstellar medium or the polyynes released by comets in their active phase.
The crystallization kinetics of as-deposited amorphous Ge2Sb2Te5 thin films has been measured by in situ time resolved reflectivity. X-ray diffraction and Raman scattering analyses of partially transformed samples allowed to correlate the evolution of the transition to the structural modification in the long and short range configuration. The experimental results evidenced that during the early stages of crystallization there is a reduction of Ge-Te tetrahedral bonds, characteristics of the Ge coordination in amorphous Ge2Sb2Te5 films.
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