Cosmic-ray exposure ages of large presolar SiC grains

Frank Gyngard, Sachiko Amari, Ernst Zinner, U. Ott

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Among presolar SiC grains found in the Murchison carbonaceous meteorites (average size less than 0.5 m) are very large grains, ranging in size up to 50 m. We interpret 6Li excesses measured in eight of these grains as being the result of spallation reactions by Galactic cosmic rays during the time the grains spent in the interstellar medium before their incorporation into the meteorite. Derived interstellar exposure ages range from 40 My to 1 Gy, the highest values being consistent with theoretical expectations of interstellar grain lifetimes. Although six grains have almost identical C and Si isotopic compositions, their exposure ages are very different. This observation, combined with low trace element contents, and unusual grain sizes, raises fundamental questions about their stellar sources.

Original languageEnglish
Pages (from-to)278-283
Number of pages6
JournalPublications of the Astronomical Society of Australia
Volume26
Issue number3
DOIs
Publication statusPublished - 2009

Fingerprint

meteorite
cosmic ray
cosmic rays
isotopic composition
grain size
trace element
carbonaceous meteorites
Murchison meteorite
spallation
meteorites
trace elements
exposure
life (durability)
incorporation

Keywords

  • Circumstellar matter
  • Cosmic rays
  • ISM: kinematics and dynamics
  • Isotopic ratios
  • Outflows
  • Stardust
  • Stars: AGB stars
  • Stars: winds

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Cosmic-ray exposure ages of large presolar SiC grains. / Gyngard, Frank; Amari, Sachiko; Zinner, Ernst; Ott, U.

In: Publications of the Astronomical Society of Australia, Vol. 26, No. 3, 2009, p. 278-283.

Research output: Contribution to journalArticle

Gyngard, Frank ; Amari, Sachiko ; Zinner, Ernst ; Ott, U. / Cosmic-ray exposure ages of large presolar SiC grains. In: Publications of the Astronomical Society of Australia. 2009 ; Vol. 26, No. 3. pp. 278-283.
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