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

We use high-precision neodymium isotope data for sequentially acid-leached components of the primitive carbonaceous chondrite Tagish Lake to identify a non-classical 150 Nd-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 150 Nd-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 ( 48 Ca, 54 Cr, 95,97 Mo, 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.