Global Distribution of Mercury's Neutrals from MESSENGER Measurements Combined with a Tomographic Method

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft entered orbit about Mercury on March 18, 2011. Since then, the Ultraviolet and Visible Spectrometer (UVVS) onboard this spacecraft has been observing Mercury's collisionless exosphere. We present measurements by MESSENGER UVVS of the sodium, calcium, and magnesium distributions that were obtained during multiple passes through the tail over a period of one month. Global maps of the exosphere were constructed daily from such measurements using a recently developed tomographic technique. During this period, Mercury moved towards the Sun from being about 0.44 astronomical units (AU) to approximately 0.32 AU from the Sun. Hence, our reconstructions provide information about the three-dimensional structure of the exosphere, the source processes for these species, and their dependence with orbital distance during the entire in-leg of Mercury's orbit

rSpeX observations of comets: Using moderate-Resolution infrared spectroscopy to infer and monitor chemical composition

International audienc

rSpeX observations of comets: Using moderate-Resolution infrared spectroscopy to infer and monitor chemical composition

International audienc

rSpeX observations of comets: Using moderate-Resolution infrared spectroscopy to infer and monitor chemical composition

International audienc

The Spatial Distributions of Volatile Species in the Comae of Comet 73P/Schwassmann-Wachmann 3 Obtained From High-Resolution Infrared Spectroscopic Observations

International audienc

Volatile Distributions in the comae of comet 73P/Schwassmann-Wachmann 3 derived from high-resolution IR spectroscopic observations

International audienc

Compositional homogeneity in the fragmented comet 73P/Schwassmann-Wachmann 3

International audienceThe remarkable compositional diversity of volatile ices within comets can plausibly be attributed to several factors, including differences in the chemical, thermal and radiation environments in comet-forming regions, chemical evolution during their long storage in reservoirs far from the Sun, and thermal processing by the Sun after removal from these reservoirs. To determine the relevance of these factors, measurements of the chemistry as a function of depth in cometary nuclei are critical. Fragmenting comets expose formerly buried material, but observational constraints have in the past limited the ability to assess the importance of formative conditions and the effects of evolutionary processes on measured composition. Here we report the chemical composition of two distinct fragments of 73P/Schwassmann-Wachmann 3. The fragments are remarkably similar in composition, in marked contrast to the chemical diversity within the overall comet population and contrary to the expectation that short-period comets should show strong compositional variation with depth in the nucleus owing to evolutionary processing from numerous close passages to the Sun. Comet 73P/Schwassmann-Wachmann 3 is also depleted in the most volatile ices compared to other comets, suggesting that the depleted carbon-chain chemistry seen in some comets from the Kuiper belt reservoir is primordial and not evolutionary

High-resolution Infrared Spectroscopy Of Comet 73P/schwassmann-Wachmann 3: A Test For Chemical Heterogeneity Within A Cometary Nucleus.

International audienc

The Spatial Distributions of Volatile Species in the Comae of Comet 73P/Schwassmann-Wachmann 3 Obtained From High-Resolution Infrared Spectroscopic Observations

International audienc

High-resolution Infrared Spectroscopy Of Comet 73P/schwassmann-Wachmann 3: A Test For Chemical Heterogeneity Within A Cometary Nucleus.

International audienc