Carbon-rich Giant Planets: Atmospheric Chemistry, Thermal Inversions, Spectra, and Formation conditions

Details Carbon-rich Giant Planets: Atmospheric Chemistry, Thermal Inversions, Spectra, and Formation conditions Carbon-rich Giant Planets: Atmospheric Chemistry, Thermal Inversions, Spectra, and Formation conditions

2011-09-14

arxiv.org/abs/1109.3183v1

Astronomy and Astrophysics

Astrophysics

Earth and Planetary Astrophysics

Accepted for publication in ApJ

Scientific paper

The recent inference of a carbon-rich atmosphere, with C/O >= 1, in the hot Jupiter WASP-12b motivates the exotic new class of carbon-rich planets (CRPs). We report a detailed study of the atmospheric chemistry and spectroscopic signatures of carbon-rich giant planets (CRGs) and the compositions of icy planetesimals required for their formation, and the apportionment of ices, rock, and volatiles in their envelopes. For C/O >= 1, most of the atmospheric oxygen is occupied by CO for T > 1400 K and pressure (P) < 1 bar, causing a substantial depletion in H2O, and an overabundance of CH4 compared to those obtained by assuming solar abundances (C/O = 0.54) in chemical equilibrium. These differences in chemistry cause distinctly observable signatures in spectra. We also find that a C/O >= 1 strongly depletes the abundances of TiO and VO available to form thermal inversions, which is adequate to rule out thermal inversions due to TiO/VO even in the most highly irradiated hot Jupiters, such as WASP-12b. Adopting stellar abundances (C/O = 0.44) for the primordial disk composition and low-temperature formation conditions (T <= 30 K) for WASP-12b leads to a C/O ratio of 0.27 in accreted planetesimals, and, consequently, in the planet's envelope. In contrast, a C/O ratio of 1 in the envelope of WASP-12b requires a substantial depletion of oxygen in the disk, by a factor of ~0.41 for the same formation conditions. This scenario also satisfies the constraints on the C/H and O/H ratios reported for WASP-12b. If, alternatively, hotter conditions prevailed in a stellar composition disk such that only H2O is condensed, the remaining gas can potentially have a C/O ~ 1. However, a high C/O in WASP-12b caused predominantly by gas accretion would preclude super-stellar C/H ratios which also fit the data.

Affiliated with

Also associated with

No associations

Rating

Carbon-rich Giant Planets: Atmospheric Chemistry, Thermal Inversions, Spectra, and Formation conditions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Carbon-rich Giant Planets: Atmospheric Chemistry, Thermal Inversions, Spectra, and Formation conditions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Carbon-rich Giant Planets: Atmospheric Chemistry, Thermal Inversions, Spectra, and Formation conditions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-671988