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Interstellar particles extracted from primitive meteorites here on earth may have lovely stories to tell about their adventures on earth, in our solar system, in interstellar space before arriving in our solar system, and even in the atmosphere of the red giant star which assembled the carbon (and other) atoms of which they are made [1].
Aberration-corrected closeup of a rim/core (top/center) interface with a binarized blue-channel brightfield showing rim (002) layers edge-on near the top, and a yellow high angle annular darkfield image showing individual heavy atom nuclei in rim and core. Yellow dot-clusters show scattering from single atomic nuclei heavier than carbon, taken with 300kV electrons, spatial resolution <1Ă…, and help from Andrew Lupini and Jing Tao of ORNL's Pennycook Lab.
At left find images in yellow, taken using a microscope at Oak Ridge National Lab [2], of scattering from single atomic nuclei possibly frozen in place during the solidification and coating of a presolar core-rim onion like Vivian, about when the core droplet solidified in the atmosphere of a carbon-producing red-giant star more than 4.5 billion years ago. The brightness of those yellow spots might, in the future, be used to count the number of protons in each nucleus, and hence to inventory heavy atoms present in that ancient star's atmosphere. For instance, a 2008 report by Zak Jost [3] suggests that here we are seeing about 500 ppma of "heavy atoms" having on the order of 18 to 30 protons, although we've not in this case examined which might be surface atoms from specimen prep.
Footnotes:
- Timothy J. Volkert and P. Fraundorf (2006) "The travel diary of a micron-sized sphere, found in the Murchison meteorite" (2006 NASA/MO space grant project, final report) pdf.
- P. Fraundorf, Tristan Hundley and Melanie Lipp (2019) "Synthesis of unlayered graphene from carbon droplets: In stars and in the lab", draft for Astrophysical Journal Letters.
- Zak Jost (2008) "Interpreting Images from a Transmission Electron Microscope" (NASA/Missouri SpaceGrant Report) 7 pages pdf.
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