Lifetimes of interstellar dust from cosmic ray exposure ages of presolar silicon carbide

Philipp R Heck; Jennika Greer; Levke Kööp; Reto Trappitsch; Frank Gyngard; Henner Busemann; Colin Maden; Janaína N Ávila; Andrew M Davis; Rainer Wieler

doi:10.1073/pnas.1904573117

Lifetimes of interstellar dust from cosmic ray exposure ages of presolar silicon carbide

Proc Natl Acad Sci U S A. 2020 Jan 28;117(4):1884-1889. doi: 10.1073/pnas.1904573117. Epub 2020 Jan 13.

Authors

Philipp R Heck^{1

2

3}, Jennika Greer^{4

2

3}, Levke Kööp^{4

2

3}, Reto Trappitsch⁵, Frank Gyngard^{6

7}, Henner Busemann⁸, Colin Maden⁸, Janaína N Ávila⁹, Andrew M Davis^{4

2

3

10}, Rainer Wieler⁸

Affiliations

¹ Robert A. Pritzker Center for Meteoritics and Polar Studies, The Field Museum of Natural History, Chicago, IL 60605; prheck@fieldmuseum.org.
² Chicago Center for Cosmochemistry, The University of Chicago, Chicago, IL 60637.
³ Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637.
⁴ Robert A. Pritzker Center for Meteoritics and Polar Studies, The Field Museum of Natural History, Chicago, IL 60605.
⁵ Nuclear and Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550.
⁶ Physics Department, Washington University, St. Louis, MO 63130.
⁷ Center for NanoImaging, Harvard Medical School, Cambridge, MA 02139.
⁸ Institute of Geochemistry and Petrology, ETH Zürich, 8092 Zürich, Switzerland.
⁹ Research School of Earth Sciences, The Australian National University, Canberra, ACT 2601, Australia.
¹⁰ Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637.

Abstract

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 ray spallation products ³He and ²¹Ne enabled us to estimate that the irradiated objects in the interstellar medium were up to 30 times larger than the analyzed grains. Furthermore, we estimate that the majority of the grains acquired the bulk of their cosmogenic nuclides in the interstellar medium and not by exposure to an enhanced particle flux of the early active sun.

Keywords: cosmochemistry; exposure age dating; interstellar dust; meteorites; presolar grains.