Reto Trappitsch | 19-FS-028
In this project we demonstrated Lawrence Livermore National Laboratory's experimental capabilities to study individual, micrometer-sized stardust grains using multiple instruments. The analyzed grains, stellar silicon carbide (SiC) condensates found in meteorites, were first deposited on sputter-cleaned gold foil and located by scanning electron microscopy. Back-scattered-electron imaging and energy dispersive x-ray analyses were used to determine the concentration of trace elements such as aluminum and magnesium. The samples were subsequently relocated in the nanoscale secondary ion mass spectrometry (NanoSIMS) instrument and analyzed for their silicon isotopic compositions to determine the type of parent star around which the stardust grains condensed. Finally, samples from low-mass stars were relocated in the laser ionization of neutrals (LION) resonance ionization mass spectrometer (RIMS) at the Laboratory and analyzed for their strontium and barium isotopic composition. The feasibility study achieved two goals: (1) to demonstrate Livermore's capability to run the techniques in-house and develop analyses protocols; and (2) to prepare stardust mounts for subsequent multi-instrument studies.
By showing the capability to analyze micrometer-sized grains with various techniques and using various instruments, we demonstrated the Laboratory's capability and expertise for experimental astrophysics. This capability will be useful for studying samples relevant to safeguards and nonproliferation missions at Livermore and within the National Nuclear Security Administration. It also positions LLNL to support outside opportunities in astrophysics and related isotopic science.
Publications, Presentations, and Patents
Heck, P. R., et al. 2019. "Evidence for Presolar Grain SiC Aggregates from Cosmogenic Nuclides." 82nd Annual Meeting of The Meteoritical Society, 2157. LLNL-ABS-772418
——— 2020. "Lifetimes of interstellar dust from cosmic-ray exposure ages of presolar silicon carbide." Proceedings of the National Academy of Sciences, 17 (4) 1884-1889. LLNL-JRNL-779857
Liu, N., et al. 2019. "Presolar Silicon Carbide Grains of Types Y and Z: Their Molybdenum Isotopic Compositions and Stellar Origins." doi:10.3847/1538-4357/ab2d27. LLNL-JRNL-765107
Stephan, T., et al. 2019. "Molybdenum Isotopes in Presolar Silicon Carbide Grains: Details of s-process Nucleosynthesis in Parent Stars and Implications for r-and p-processes." The Astrophysical Journal 877, 2: 101. LLNL-JRNL-768104
Trappitsch, R. 2019. Deciphering astrophysical processes by analyzing stardust grains: The past, the present, and the future." Invited talk at the University of Perugia, Italy, June 2019. LLNL-PRES-779819
——— 2019. "Extraterrestrial Pu and Presolar Grain Analyses: Hands-on Astrophysics at LLNL." Presolar Grain Workshop, University of Chicago, Chicago, IL, October 2019. LLNL-PRES-795439