Stardust Interstellar Preliminary Examination VII: Synchrotron X‐ray fluorescence analysis of six Stardust interstellar candidates measured with the Advanced Photon Source 2‐ID‐D microprobe

Abstract The NASA Stardust spacecraft exposed an aerogel collector to the interstellar dust passing through the solar system. We performed X‐ray fluorescence element mapping and abundance measurements, for elements 19 ≤  Z  ≤ 30, on six “interstellar candidates,” potential interstellar impacts identified by Stardust@Home and extracted for analyses in picokeystones. One, I1044,3,33, showed no element hot‐spots within the designated search area. …