Liu, NanNanLiuStephan, ThomasThomasStephanCRISTALLO, SergioSergioCRISTALLOVESCOVI, DIEGODIEGOVESCOVIGallino, RobertoRobertoGallinoNittler, Larry R.Larry R.NittlerAlexander, Conel M.O’ D.Conel M.O’ D.AlexanderDavis, Andrew M.Andrew M.Davis2023-01-202023-01-2020221434-6001http://hdl.handle.net/20.500.12386/32969We report the Sr and Ba isotopic compositions of 18 presolar SiC grains of types Y (11) and Z (7), rare types commonly argued to have formed in lower-than-solar metallicity asymptotic giant branch (AGB) stars. We find that the Y and Z grains show higher 88Sr/87Sr and more variable 138Ba/136Ba ratios than mainstream (MS) grains. According to FRANEC Torino AGB models, the Si, Sr, and Ba isotopic compositions of our Y and Z grains can be consistently explained if the grains came from low-mass AGB stars with 0.15 Z⊙ ≤ Z < 1.00 Z⊙, in which the 13C neutron exposure for the slow neutron-capture process is greatly reduced with respect to that required by MS grains for a 1.0 Z⊙ AGB star. This scenario is in line with the previous finding based on Ti isotopes, but it fails to explain the indistinguishable Mo isotopic compositions of MS, Y, and Z grains.STAMPAenArticle10.1140/epja/s10050-022-00838-z2-s2.0-85141782303https://api.elsevier.com/content/abstract/scopus_id/85141782303https://link.springer.com/article/10.1140/epja/s10050-022-00838-zFIS/05 - ASTRONOMIA E ASTROFISICA