An ongoing project in our group is the study of isotopic composition of trace elements in presolar SiC grains, including mainstream and special (A, B, X, Y) grains. We have also begun to study the isotopic composition of carbide inclusions found within presolar graphite grains.
(Image credits: NASA and Larry Nittler)
Micron-sized stardust grains can be extracted from primitive meteorites. Such grains originated billions of years ago in the ashes of supernovae. Laboratory analysis of such tiny dust grains provides unique astrophysical information, such as stellar nucleosynthesis and evolution, Galactic chemical evolution, grain formation, chemical and physical processes in the ISM, and the types of stars that contributed dust to our Solar System.
Presolar grains can come in the form of SiC, graphite, spinel, and silicates (below, image credit: Peter Hoppe). The isotopic ratios of the major and minor elements in presolar grains range over many orders of magnitude and are indicative of contributions from different stellar sources. Using CHILI we can measure the isotopic ratios for different elements in presolar grains with high resolution.
The Presolar Grain Database has been formed under efforts of the CHILI Lab and the Laboratory for Space Sciences at Washington University St. Louis. The database provides isotopic information for various elements and grain types.
SiC
Spinel
Graphite
Silicate
Nitrogen versus carbon isotope ratios and silicon 3-isotope plots for SiC grains.
(Image credit: Presolar Grain Database)
Relevant Papers Recently Published by CHILI Lab:
Bloom H. E., Stephan T., Davis A. M., Heck P. R., Hoppe P., Korsmeyer J. M., and Amari S. (2022) s-Process molybdenum, ruthenium, and barium in high-density presolar graphite (abstract). Lunar Planet. Sci. 53, #2624. [pdf]
Stephan T., Bloom H. E., Davis A. M., Hoppe P., Korsmeyer J. M., Pellin M. J., Regula A., and Sheu S. (2021) Correlated molybdenum and ruthenium isotopes in presolar silicon carbide (abstract). Meteorit. Planet. Sci. 56, A252 (#6270). [pdf]
Stephan T., Bose M., Boujibar A., Davis A. M., Gyngard F., Hoppe P., Hynes K. M., Liu N., Nittler L. R., Ogliore R. C., and Trappitsch R. (2021) The Presolar Grain Database for silicon carbide—grain type assignments (abstract). Lunar Planet. Sci. 52, #2358. [pdf]
Boujibar A., Howell S., Zhang S., Hystad G., Prabhu A., Liu N., Stephan T., Narkar S., Eleish A., Morrison S. M., Hazen R. M., and Nittler L. R. (2021) Cluster analysis of presolar silicon carbide grains: Evaluation of their classification and astrophysical implications. Astrophys. J. Lett. 907, L39 (14pp). [html]
Trappitsch R., Stephan T., Savina M. R., Davis A. M., Pellin M. J., Rost D., Gyngard F., Gallino R., Bisterzo S., Cristallo S., and Dauphas N. (2018) Simultaneous iron and nickel isotopic analyses of presolar silicon carbide grains. Geochim. Cosmochim. Acta 221, 87–108. [html]