Carbon-isotope ratio in PUMA 1 spectra of P/Halley dust
Carbon isotopes 12C and 13C have yet been identified both in cometary gas and dust. Although the determination from optical C2 and CN emissions from ground-based observations is not precise, the ratio 12C/13C is roughly the same as the mean ratio derived from PUMA 1 mass spectra of cometary grains. This value both in volatile and refractory material does not differ much from the nominal solar system value 90. However, the collection of 38 PUMA 1 mode 0 spectra shows surprisingly variable 12/13 amu lines ratio within 3 decades, increasing with carbon abundance in the grains. Possible instrumental effects are discussed.
Key wordscomets isotopic ratio
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