travels of a cai revealed by oxygen isotopes
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Travels of a CAI Revealed by Oxygen Isotopes. Minerals from a CAI and its prominent rim have a wide range of oxygen isotopic composition, suggesting formation in more than one reservoir. Oxygen Isotopic Zoning. Melilite interior has high 16 O (low 17 O) - PowerPoint PPT PresentationTRANSCRIPT
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Travels of a CAI Revealed by Oxygen Travels of a CAI Revealed by Oxygen IsotopesIsotopes
Nebula travels revealed by O-isotopes
Minerals from a CAI and its prominent rim have a wide range of oxygen isotopic composition, suggesting formation in more than one reservoir.
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Oxygen Isotopic ZoningOxygen Isotopic Zoning
Nebula travels revealed by O-isotopes
• Melilite interior has high 16O (low 17O)• 17O increases (so 16O decreases) towards the rim• Spinel-rich region of Wark-Lovering rim has extremely low 17O• Most of the rim oscillates around the value of the CAI interior• These data clearly indicate exposure of the CAI and its rim to environments that varied in oxygen isotopic composition• Implies extensive migration throughout the solar nebula
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Other Evidence for TransportOther Evidence for Transport
Nebula travels revealed by O-isotopes
Meteorite data and astrophysical models suggest extensive transport from the inner to outer solar nebula. Silicates in comets support the idea. The new oxygen data show transport back in towards the Sun.
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Comet Sample Return from the Stardust Comet Sample Return from the Stardust Mission Reveal a Chondrule’s TravelsMission Reveal a Chondrule’s Travels
Nebula travels revealed by O-isotopes
• Comet particles collected by the Stardust mission contain chondrules and CAIs that formed at much higher temperatures than those prevailing where the icy comet accreted
• These high-temperature objects must have formed closer to the Sun and moved out beyond the planets to the comet-forming region in the Kuiper belt
• Analyses on one of these chondrule fragments, called “Iris,” reveals its history of formation and outward transport
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What’s Jupiter Got to Do With It?What’s Jupiter Got to Do With It?
Nebula travels revealed by O-isotopes
• Oxygen isotopic composition of Iris is similar to terrestrial oxygen, suggesting formation in the inner solar nebula
• Al-Mg isotope systematics place the formation age of Iris >3 Myr after CAIs
• Iris must have moved out to the comet-forming region before Jupiter could have blocked its way
• Timing implies Jupiter formed more than 3 Myr after CAIs