C/O Distribution of Planet Search Stars

None of the 849 F, G, and K dwarfs in this sample of planet search stars has C/O > 0.7. This distribution is in agreement with galactic chemical evolution models and means that the likelihood of finding diamond planets is quite low. It does, however, mean that the Mg/Si ratios of these stars can tell us about the geology of any rocky planets in the system.

C/O vs. Metallicity

Previous studies have shown a correlation between metallicity (as measured by [Fe/H]) and the C/O ratio. Our sample largely agrees at [Fe/H] < -0.1, but seems to flatten out for more metal rich stars. This also agrees with galactic chemical evolution models that expect C/O ratios to plateau.