Evidence for extinct 135Cs from Ba isotopes in Allende CAIs

摘要: Abstract The abundance and distribution of isotopes throughout the Solar System can be used to constrain number type nucleosynthetic events that contributed material early nebula. Barium is particularly well suited quantifying degree isotope heterogeneity in because it comprises seven stable were synthesized by three different processes (s-, r-, p-processes), all which System. There also potential contribution 135 Ba from short-lived radioisotope Cs, conclusive evidence for yet reported. Four Allende (CV3) Ca,Al-rich inclusions (CAI 1, CAI 2, 4, 5) one dark inclusion (DI) analyzed variability. Two CAIs 2 display excesses are not accompanied 137 anomalies. Calcium–aluminum-rich 1 displays a excess possibly coupled with excess, remaining refractory DI) have terrestrial compositions. These data presented conjunction published whole rock individual CAIs. enrichment absence 5 interpreted indicate anomalies purely origin but contain contributions (16–48 ppm) decay Cs. majority studied date may similar Cs on basis higher than expected if origin. appear superchondritic Cs/Ba, imply did occur via situ live However, feasible had Cs/Ba during was subsequently removed system aqueous alteration parent body. An alternative scenario existence transient high-temperature reservoir having while extant, enabled radiogenic signature develop some condensates. source determined reconciling predicted astrophysical its measured meteorites. Further, currently accepted initial Cs/ 133 System, [ Cs] 0 , underestimated spread among samples small range limited thus leading inaccuracies when estimating . If meteoritic indeed thought, most probable stellar radioisotopes nearby core-collapse supernova and/or Wolf–Rayet wind driven progenitor.