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The NC–CC isotopic dichotomy

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Key words

Isotope

One of two or more forms of the same chemical element whose atoms have different numbers of neutrons, and so different masses.

Meteorite

A meteorite is a piece of space rock that has survived its fall through the air and landed on Earth.

Jupiter

Jupiter is the largest planet in the Solar System, whose gravity shapes the asteroid belt and steers meteoroids towards Earth.

Mass-dependent fractionation

Mass-dependent fractionation is the sorting of isotopes by mass during processes such as evaporation and diffusion.

Mass spectrometer

A mass spectrometer is an instrument that separates atoms or molecules by mass to measure isotopes and elements.

Chondrite

A chondrite is a stony meteorite full of tiny round grains called chondrules, and almost unchanged since the Solar System formed.

Choose the right answer

Circle the letter of the right answer.

1. When may Earth's CC component have arrived, according to mass-balance studies?
   • AOnly at the very start of accretion
   • BWithin the last billion years
   • CRelatively late in Earth's growth
   • DNever: Earth contains no CC material
2. Where do the samples returned from Ryugu and Bennu plot?
   • AIn the CC field
   • BIn the NC field
   • CExactly on the Earth value
   • DBetween the two fields
3. What gives rise to nucleosynthetic isotope anomalies between Solar System bodies?
   • ALong exposure to cosmic rays while drifting in space
   • BImperfect mixing of material from different stars
   • CMass-dependent fractionation during melting on parent bodies
   • DRadioactive decay after the bodies had accreted
4. A parent body melts and forms a core. What happens to its nucleosynthetic anomalies?
   • AThey shift along a slope of 0.52
   • BThey are reset to Earth's values
   • CThey are preserved
   • DThey are erased by the melting
5. What does the dichotomy show that meteorites can record?
   • AOnly the chemistry of the young Sun itself
   • BOnly the history of their own parent body
   • COnly events after the planets were complete
   • DThe large-scale dynamics of the young disc

True or false?

Is the answer given right? Tick True or False.

6. When sorting groups into NC and CC columns, where do CV chondrites and IIIAB irons go?

   Answer given: Both in NC TrueFalse

7. Which iron meteorite group belongs to the CC reservoir?

   Answer given: IVB TrueFalse

Write your answer

Answer in a word or a short sentence.

8. Why do hafnium-tungsten ages of iron meteorites matter for the dichotomy?
9. Why are molybdenum isotopes especially good at revealing the dichotomy?
10. On the Jupiter-barrier view, where did CC material form?

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