Graduate Student Seminar with Mary Iskakova on Low Initial Abundance of 26Al in a Cometary Particle

²⁶Al is a short-lived radionuclide that decays to ²⁶Mg with a half-life of 0.717 Myr. It was present in the early solar system and was an important heat source of early accreted planetesimals. The initial distribution of ²⁶Al in the early solar system remains controversial. Previous measurements of the Al-Mg system in cometary samples (Stardust samples from comet Wild 2, or giant cluster interplanetary dust particles which are probably from comets) show no resolved initial ²⁶Al/²⁷Al ratio. All of the previously measured initial ²⁶Al/²⁷Al upper bounds were below the 5.2x10-5 canonical value. Here I will report measurements of the ²⁶Al-²⁶Mg system in particle P3-4, a calcium-aluminum rich inclusion from U2-20 GCP, a giant cluster interplanetary dust particle of likely cometary origin. Similar to other cometary particles, P3-4 shows no evidence for the incorporation of live ²⁶Al during its formation or a subsequent heating event.