... abundances

Appendices are only available in electronic form at http://www.edpsciences.org

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...(Coplen et al. 2002)

The geological manner of expressing such measurements is in "permil'', a deviation in parts per thousand from the terrestrial value:

$$% \delta^b{\rm X} = 1000 \times \left( \frac {(^b {\rm X}/^a ... ...})_{{\rm sample}}} {(^b {\rm X}/^a {\rm X})_\oplus} - 1\right)$$ (1)

where X is the element in question, a refers to its reference isotope and b to the isotope in question. It should be realised that the "terrestrial ratios'' given above are from standard substances chosen to define the zero-point of this scale; in reality, the terrestrial isotopic composition varies far more than the errors attached to these values appear to suggest (Coplen et al. 2002; Rosman & Taylor 1998).

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... "1DAV''

"One Dimensional AVerage''.

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... mission

http://thunder.jpl.nasa.gov/atmos/at3.solar

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... work

The $\log gf$ values were typically 0.02 dex larger in the Harris et al. (1987) study, so these are unlikely to have affected ratios. None of the weak ¹²C¹⁶O lines we have used were employed by Harris et al. Equivalent widths for the few common isotopomeric lines were larger on average in their study, leading to an underprediction of isotopic abundances and therefore an overprediction of ratios.

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...

Adopting Ayres et al.'s smaller equivalent widths, and considering the resultant average change in abundances over the small number of lines common to the two studies, as well as discarding the opacity scalefactors, we would obtain ¹²C/ $^{13}{\rm C}=80.9$ and ¹⁶O/ $^{18}{\rm O}=452$ for the 1DAV model using the weak ¹²C¹⁶O list. This is in comparison to ¹²C/ $^{13}{\rm C}=80.7$ $\pm$ 3.8 and ¹⁶O/ $^{18}{\rm O}=443$ $\pm$ 31 obtained by Ayres et al. using the same model.

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