Key points are not available for this paper at this time.
The C/O ratio is predicted to regulate the atmospheric chemistry in hot. Recent observations suggest that some exo-planets, e. g. Wasp 12- b, atmospheric C/O ratios substantially different from the solar value of0. 54. In this paper we present a mechanism that can produce such atmospheric from the stellar C/O ratio. In protoplanetary disks, different of oxygen- and carbon-rich ices, especially water and carbon, will result in systematic variations in the C/O ratio both in the gas in the condensed phase. In particular, between the H2O and CO snowlines oxygen is present in icy grains - the building blocks of planetary cores the core accretion model - while most carbon remains in the gas-phase. This is coincidental with the giant-planet forming zone for a range of protoplanetary disks. Based on standard core accretion models of formation, gas giants that sweep up most of their atmospheres from disk outside of the water snowline will have C/O? 1, while atmospheres contaminated by evaporating planetesimals will have stellar or-stellar C/O when formed at the same disk radius. The overall metallicity also depend on the atmosphere formation mechanism, and exoplanetary compositions may therefore provide constraints on where and how a planet formed.
Öberg et al. (2011) studied this question.