biostudies-literatureHeck PRU.S. Department of EnergyTawani FoundationSwiss National Science FoundationNational Aeronautics and Space AdministrationField MuseumDOE | LDRD | Lawrence Livermore National LaboratoryMCTI | Conselho Nacional de Desenvolvimento Científico e TecnológicoNational Science Foundation1884-1889https://www.ebi.ac.uk/biostudies/studies/S-EPMC6995017biostudies-literatureUnknown117(4)We determined interstellar cosmic ray exposure ages of 40 large presolar silicon carbide grains extracted from the Murchison CM2 meteorite. Our ages, based on cosmogenic Ne-21, range from 3.9 ± 1.6 Ma to ∼3 ± 2 Ga before the start of the Solar System ∼4.6 Ga ago. A majority of the grains have interstellar lifetimes of <300 Ma, which is shorter than theoretical estimates for large grains. These grains condensed in outflows of asymptotic giant branch stars <4.9 Ga ago that possibly formed during an episode of enhanced star formation ∼7 Ga ago. A minority of the grains have ages >1 Ga. Longer lifetimes are expected for large grains. We determined that at least 12 of the analyzed grains were parts of aggregates in the interstellar medium: The large difference in nuclear recoil loss of cosmic rProceedings of the National Academy of Sciences of the United States of AmericaLifetimes of interstellar dust from cosmic ray exposure ages of presolar silicon carbide.PMC6995017DE-AC52-07NA27344NNX11AG77G80NSSC17K0251Major grant to Field Museum200081/2005-5NCCR PlanetS19-FS-028DGE-1144082DGE-1746045NNX15AC53GNNX15AF78GVisiting Scholarship80NSSC19K0504Greer JTrappitsch RHeck PRWieler RKoop LMaden CGyngard FBusemann HAvila JNDavis AMfalseLifetimes of interstellar dust from cosmic ray exposure ages of presolar silicon carbide.We determined interstellar cosmic ray exposure ages of 40 large presolar silicon carbide grains extracted from the Murchison CM2 meteorite. Our ages, based on cosmogenic Ne-21, range from 3.9 ± 1.6 Ma to ∼3 ± 2 Ga before the start of the Solar System ∼4.6 Ga ago. A majority of the grains have interstellar lifetimes of <300 Ma, which is shorter than theoretical estimates for large grains. These grains condensed in outflows of asymptotic giant branch stars <4.9 Ga ago that possibly formed during an episode of enhanced star formation ∼7 Ga ago. A minority of the grains have ages >1 Ga. Longer lifetimes are expected for large grains. We determined that at least 12 of the analyzed grains were parts of aggregates in the interstellar medium: The large difference in nuclear recoil loss of cosmic r2020-01-01T00:00:00Z2020 Jan2025-04-19T10:54:57.562Z2020-05-22T09:33:16ZS-EPMC69950173193242310.1073/pnas.1904573117