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cOmetary GRains and Early Solar System Evolution: Isotopic analyses of cometary polar micrometeorites – OGRESSE

Searching for the frontier between the asteroidal and the cometary world.

Extraterrestrial dust coming from the cometary reservoir have been identified in a collection performed at the vicinity of the polar station CONCORDIA (central regions of Antarctica). The aim of this project is to analyze their chemical and isotopic composition to shed light on the astrophysical context of the solar system birth.

Analysis of cometary micrometeorites coming from comets.

Analysis of extraterrestrial material allows approaching various fields of research spanning from stellar nucleosynthesis in generations of stars prior the Sun to planetary evolution. The ORGRESSE project to tackle fundamental questions regarding: i) the interstellar component present in cometary material, ii) the origin of organic matter in the solar system, iii) the nuclear origin of short lived radionucleides that were present in the protoplanetary disk. The ultracarbonaceous Antarctic micrometeorites (UCAMMs) from the CONCORDIA collection exhibit striking similarities with the CHON grains observed in Halley comet. Both their chemical and isotopical composition strongly suggest that UCAMMs are coming from the cometary reservoir. We propose to infer the concentration in presolar grains in UCAMMs and to measure their light element isotopic composition (H and N). The aim of this study is to draw the frontier between the interstellar heritage and the processes that took place in the accretion disk during the first million years after the gravitational collapse of the proto-sun.

The OGRESSE project propose to explore the possibilities to perform secondary ion mass spectrometry using polyatomic ions. This isotopic imaging program is aiming to develop the possibilities of the ion-probe NanoSims. The use of this up-to-date instrument at very high mass resolution is not trivial and will require analytical developments. A substantial gain in sensitivity is expected in the case where the polyatomic species have a higher electronic affinity than that of the element of interest.
The UCAMMs provide a unique access to the close association between silicates and organic matter coming from the colder regions of the protoplanetary disk. The isotopic composition of the various components of UCAMMs will be compared to that of primitive solar system objects (e.g. comets, carbonaceous chondrites, unequilibrated ordinary chondrites…)
The CSNSM micrometeorites collection will be modernized in order to improve it’s curation conditions. A systematic search for new ultracarbonaceous grains and other new type of interplanetary dust particles will be launched.

We characterized the organic matter of ultracarbonaceous micrometeorites by means of Infrared and Raman spectrometry and secondary ion mass spectrometry (SIMS). The particles analyzed contain unusually high Nitrogen concentrations. Both the chemical and isotopic composition strongly suggests that they originate from parent body located beyond Neptune orbit. These micrometeorites provide clues to the composition of the solid phase of objects among the most remote of our solar system. This work is part of collaboration between two ANR programs (COSMISME and OGRESSE) and was published in Icarus, Dartois et al. 2013.
An experimental and theoretical work was performed under the direction of G. Slodzian on the Nanosims of the Institut Curie (Orsay). This work allowed to substantially improving the mass resolution of the instrument. The results were published in Microscopy & Microanalysis, Slodzian et al 2014.
Thanks to the support of French and Italian polar institutes (IPEV & PNRA) we performed a new micrometeorite collection in central Antarctic regions in January 2014. The collects were performed in trenches at the vicinity of the station CONCORDIA at Dome C.

The improvements achieved on the Nanosims open perspectives on mass spectrometry using polyatomic ions for cosmo-chemistry. It allows measuring simultaneously Nitrogen (15N12C/14N12C) and deuterium (as C2D/C2H) on the same sample. We are planning to study the spatial correlations between 15N and D excesses in UCAMM organic matter.

Microscopy and Microanalysis 2014, vol. 20, issue 02, pp. 577-581,
Simultaneous Hydrogen and Heavier Element Isotopic Ratio Images with a Scanning Submicron Ion Probe and Mass Resolved Polyatomic Ions
Slodzian, Georges; Wu, Ting-Di; Bardin, N

The general framework of the present project is the astrophysical context of the solar system formation and its evolution during the first millions of years after the gravitational collapse of the proto-Sun. It is in the continuity of a previous ANR (MICMET-ISO, 2005-2008) on the study of the asteroid-comet continuum through the analyses of micrometeorites (interplanetary dust particles) collected from central Antarctic snow (CONCORDIA Collection). Major results of our previous ANR program include: (i) the discovery of a new type of interplanetary dust (i.e. ultracarbonaceous micrometeorites, UCAMMs) of most probable cometary origin (Duprat et al., Science 2010), (ii) the evaluation of the maximum mass of short lived radionuclides that can be produced by irradiation in the early solar system (Duprat & Tatischeff ApJ 2007). This latter theoretical work allowed us to set constraints on the origin of extinct radioactivities that might be identified in cometary samples such as STARDUST samples or UCAMMs.

From these results, our new program OGRESSE proposes to tackle several fundamental questions:
- Is it possible to quantify the upper limit on interstellar material in cometary samples?
- What is the origin of organic matter in the protoplanetary disk?
- Is it possible to conceive a coherent and self-consistent astrophysical scenario to account for the origin of the short-lived radionuclides present in the protoplanetary disk and how are they related to the formation of the solar system?

This OGRESSE multitask program will involve isotopic analyses of cometary UCAMMs to investigate both the interstellar heritage of cometary grains and the origin of organic matter (OM) in the solar system. The latter will benefit from instrumental developments on secondary ion mass spectrometry using state-of-the-art instruments (NanoSIMS). In parallel, the input from a runaway Wolf-Rayet star in the protosolar nebula will be theoretically estimated. We will also search for new objects in the CSNSM micrometeorite collections, and open them to the international community through the development of a digitized web-based database.

The UCAMMs from the CONCORDIA collection have no counterparts in any other collection of extraterrestrial matter, but they show similarities with the CHON particles observed in comet Halley in 1986. UCAMMs are most probably of cometary origin, and they are more than 10 times more massive than the comet Wild 2 samples returned by the STARDUST mission. The UCAMMs represent a unique opportunity to study an ultra-primitive OM reservoir from the cold regions of the protoplanetary disk, and its associated mineral phases, without any chemical processing of the samples. To assess the interstellar heritage of the protosolar nebula and the dynamics of the protoplanetary disk, we will use isotopic analyses to quantify the presolar grain concentration of UCAMMs. To shed light on physico-chemical processes acting in the cold regions of the protoplanetary disk, we will study the isotopic compositions of light elements (H and N) in the UCAMM OM, in comparison with those of comet Wild2 samples. We will develop analytical procedures in secondary ion mass spectrometry (SIMS) using the polyatomic secondary (ionic) emission (PSE) to improve the precision of isotopic measurements with the state-of-the-art NanoSIMS.

In the continuity of the scenario in which the solar system formed at the vicinity of a runaway Wolf-Rayet star (Tatischeff, Duprat et al., ApJ 2010), we propose to study from a theoretical point of view the implications of this specific astrophysical context on the isotopic heritage expected in the protoplanetary disk.

Finally, we propose to open the unique resources of the CONCORDIA collection to the international community. In order to achieve this goal, we need to identify and characterize more UCAMM particles, search for other types of exotic particles, and create a web-based database for all types of micrometeorites.

Project coordinator

Monsieur Jean Duprat (CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR SUD) – Jean.Duprat@csnsm.in2p3.fr

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CSNSM CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR SUD
MNHN CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR EST

Help of the ANR 318,500 euros
Beginning and duration of the scientific project: January 2012 - 48 Months

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