Final Report Summary - CEMYSS (Cosmochemical Exploration of the first two Million Years of the Solar System)
The aims of the CEMYSS (Cosmochemical Exploration of the first Million Years of the Solar System) project was to make a step forward in the understanding of the formation and early evolution of the Solar system from the measurement at high precision (ppm to permil level) and high spatial resolution (nanometer to micrometer scale) of the isotopic composition of meteorites and other extra-terrestrial samples. Recent astrophysical observations and modelling of young stars of Solar mass and of their accretion disks, demonstrate that the first few million years is a key period for the formation of the first grains and first planets. Samples of this early period, when the Sun was not yet totally built, are "fossilized" in meteorites. Variations in the isotopic composition of various components of meteorites provide constraints on transport processes in the disk, gas-solid reactions, timing and chronology of the different steps from the nebular gas to the planets. These variations of isotopic compositions are difficult to measure, which necessitated the development of new analytical approach with the ion microprobes of the french national ion microprobe laboratory in CRPG-CNRS (Nancy, France).
Developments of the measurement of nitrogen isotopic composition with a nanometric spatial resolution, using depth profiling with an ion microprobe, allowed to determine for the first time the isotopic composition of Solar wind nitrogen implanted in the collectors of the NASA GENESIS mission. This early result of the CEMYSS project revealed that the Sun, and by inference the nebular gas, is extremely different (14N-rich) in isotopic composition from all terrestrial planets and meteorites, pointing to large isotopic variations in the accretion disk, variations due to processes which are not yet fully understood.
Short-lived radioactive nuclides (SLRs) are other powerful tracers of the astrophysical environment for the birth of the Solar system, of the dynamic of the disk, and of the interactions between the active early Sun, the nebula gas and the first solids. Developments of isotopic measurements of trace isotopes by large radius high mass-resolution ion microprobe made possible to improve during the CEMYSS project the determination of the abundance and distribution in the accretion disk of several key SLRs: 60Fe which is tracer of the incorporation in the forming Solar system of presolar stellar products, 10Be which is a tracer of the irradiation of the accretion disk by the cosmic rays emitted by the young active forming Sun, and 41Ca which is key since it could have a mixed origin and has a very short half-life.
A major effort of the CEMYSS project was devoted to the study of the distribution of 26Al, which is no contest the most important of the SLRs, since it could provide the most precise chronology of all the processes from the gas to the first planets. Using multi-collector large radius ion microprobe we could reach for the first time a precision in the measurement of the Mg isotopic composition (26Mg is the decay product of 26Al) allowing to test the homogeneity of the distribution of Al and Mg isotopes in the disk and giving access to a precise chronology for the processes from the gas to the first solids and to the first planets. According to these results accretion of objects en route to planets started very early, a few hundred thousand years after the start of the Solar system, and was shortly followed by planetary formation. Using high-precision isotopic measurements of the oxygen isotopic composition, we could identify fragments of these first-formed planets, which were likely destroyed by energetic collisions with similar objects within the first two million years of Solar system history.
As a whole, these different results of the CEMYSS project reveal the dynamic of the young Solar system and set the base for joint progress in cosmochemistry/astrophysics towards a unified model of the formation of the Solar system.
Developments of the measurement of nitrogen isotopic composition with a nanometric spatial resolution, using depth profiling with an ion microprobe, allowed to determine for the first time the isotopic composition of Solar wind nitrogen implanted in the collectors of the NASA GENESIS mission. This early result of the CEMYSS project revealed that the Sun, and by inference the nebular gas, is extremely different (14N-rich) in isotopic composition from all terrestrial planets and meteorites, pointing to large isotopic variations in the accretion disk, variations due to processes which are not yet fully understood.
Short-lived radioactive nuclides (SLRs) are other powerful tracers of the astrophysical environment for the birth of the Solar system, of the dynamic of the disk, and of the interactions between the active early Sun, the nebula gas and the first solids. Developments of isotopic measurements of trace isotopes by large radius high mass-resolution ion microprobe made possible to improve during the CEMYSS project the determination of the abundance and distribution in the accretion disk of several key SLRs: 60Fe which is tracer of the incorporation in the forming Solar system of presolar stellar products, 10Be which is a tracer of the irradiation of the accretion disk by the cosmic rays emitted by the young active forming Sun, and 41Ca which is key since it could have a mixed origin and has a very short half-life.
A major effort of the CEMYSS project was devoted to the study of the distribution of 26Al, which is no contest the most important of the SLRs, since it could provide the most precise chronology of all the processes from the gas to the first planets. Using multi-collector large radius ion microprobe we could reach for the first time a precision in the measurement of the Mg isotopic composition (26Mg is the decay product of 26Al) allowing to test the homogeneity of the distribution of Al and Mg isotopes in the disk and giving access to a precise chronology for the processes from the gas to the first solids and to the first planets. According to these results accretion of objects en route to planets started very early, a few hundred thousand years after the start of the Solar system, and was shortly followed by planetary formation. Using high-precision isotopic measurements of the oxygen isotopic composition, we could identify fragments of these first-formed planets, which were likely destroyed by energetic collisions with similar objects within the first two million years of Solar system history.
As a whole, these different results of the CEMYSS project reveal the dynamic of the young Solar system and set the base for joint progress in cosmochemistry/astrophysics towards a unified model of the formation of the Solar system.