par Olivier Poch (IPAG)
Abstract :
Solar system small bodies were the first objects to accrete inside the protoplanetary disk, so they give insights into its composition and structure. The smallest and darkest small bodies (among comets, P/D/X/C/B-type asteroids etc.) are made of the remnant protoplanetary disk dust, which has been more or less altered since their accretion depending on the object. Why do these objects have such a low albedo? Why do they exhibit diverse spectra at visible and infrared wavelengths? And how to infer their composition via infrared remote sensing?
I will present laboratory experiments providing some answers to these questions, via the production of granular samples made of sub-micrometer-sized grains analogue to these low albedo small bodies, and the measurement of their reflectance spectra. The optical separation of sub-micrometer-sized grains seems to be a major parameter controlling the optical properties of these objects.
In addition, pieces of some of these objects, meteorites or samples returned by space missions, can be directly analyzed for their chemical composition in the laboratory. I will present analyses aiming at identifying the nitrogen carrier phases (organic matter, ammonium) in carbonaceous chondrite meteorites and returned samples.
Lieu : salle 1-2-3, bât. 121, IAS