Carbon planets rarer than previously thought?

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Carbon planets rarer than previously thought?

Post by Lazarus on 10th January 2012, 6:07 pm

On the Carbon-to-Oxygen Ratio Measurement in Nearby Sunlike Stars: Implications for Planet Formation and the Determination of Stellar Abundances

There do not appear to be enough cool carbon-rich stars that would be expected if the proportion of stars with high C/O ratios is as great as has been previously estimated. This may indicate problems with the way these ratios are determined. If so, carbon planets may be rarer than previously thought.
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Re: Carbon planets rarer than previously thought?

Post by Lazarus on 10th March 2013, 7:11 am

The carbon-to-oxygen ratio in stars with planets
http://arxiv.org/abs/1303.1726

from the abstract:
Aiming for more precise C/O ratios, oxygen abundances in this paper are derived from the high-excitation OI triplet at 7774 A and carbon abundances from the CI lines at 5052 and 5380 A using MARCS model atmospheres and including non-LTE corrections. The results do not confirm the high C/O ratios previously found. C/O shows a tight, slightly increasing dependence on metallicity from C/O=0.58 at [Fe/H]=0.0 to C/O=0.70 at [Fe/H] =0.4 with an rms scatter of only 0.06. Assuming that the composition of a proto-planetary disk is the same as that of the host star, the C/O values found in this paper lend no support to the existence of carbon-rich planets.
55 Cancri is mentioned in the introduction but is not one of the stars listed in the tables at the end.
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