Isotope Dichotomy from Solar Protoplanetary Disk Processing of 150 Nd-rich Stellar Ejecta

• Published in: The Astrophysical Journal Letters
• Main Authors: Saji, Nikitha Susan, Schiller, Martin, Holst, Jesper Christian, Bizzarro, Martin
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: CAPTURE CROSS-SECTIONS; S-PROCESS; NEUTRON-CAPTURE; BUILDING-BLOCKS; LOW-METALLICITY; MASSIVE STARS; ND; HETEROGENEITY; ORIGIN; ANOMALIES; Tagish
• Online Access: https://curis.ku.dk/portal/da/publications/isotope-dichotomy-from-solar-protoplanetary-disk-processing-of-150ndrich-stellar-ejecta(95c191a9-6cf2-4f3e-b9fc-052b7f182ac1).html; https://doi.org/10.3847/2041-8213/ac1e26; https://curis.ku.dk/ws/files/281282919/Isotope_Dichotomy_from_Solar_Protoplanetary_Disk_Processing_of_150Nd_rich_Stellar_Ejecta.pdf

We use high-precision neodymium isotope data for sequentially acid-leached components of the primitive carbonaceous chondrite Tagish Lake to identify a non-classical Nd-150-rich presolar carrier phase that has not been identified as of yet in meteorites. The distinct isotopic signature of this carrier can be attributed to the intermediate neutron capture process (i-process) occurring in asymptotic giant branch (AGB), super-AGB, or post-AGB stars or, alternatively, the slow capture process (s-process) occurring in rotating massive stars. The Nd-150-rich carrier appears to be heterogeneously distributed in the solar protoplanetary disk resulting in systematic isotope variations between carbonaceous and non-carbonaceous solar system materials. Carbonaceous chondrites that accreted in the outer disk are depleted in this carrier relative to non-carbonaceous materials that accreted in the terrestrial planet-forming region. Calcium-aluminum-rich inclusions that represent the earliest formed disk solids record the largest depletion of this carrier. This distribution pattern is contrary to that seen for the carriers of other neutron-rich isotope anomalies (Ca-48, Cr-54, Mo-95,Mo-97, etc.) that have defined carbonaceous/non-carbonaceous isotope dichotomy so far. Irrespective of the exact astrophysical origin of these carriers, divergent distribution of presolar dust as a function of physicochemical processing in the solar protoplanetary disk best explains the solar system isotope dichotomy as opposed to changes in the composition of the infall.