Institute of Astronomy

Constraining the carbon and oxygen abundances of hot Jupiter atmospheres using ground-based very high-resolution spectroscopy

SpeakerTalk DateTalk Series
Jayne Birkby1 August 2014Across HR 2014 Talks


The chemical composition of a hot Jupiter atmosphere has the potential to place unique constraints on precisely how and where in the proto-planetary disk the planet formed. This is due to the varying abundances of gaseous carbon- and oxygen-bearing molecules throughout the proto-planetary disk, and requires a robust, reliable determination of the carbon-to-oxygen ratio in the planet's atmosphere. I will present ground-based high-resolution (R~100,000) spectra from CRIRES/VLT at 3.2 and 3.5 microns of several transiting and non-transiting hot Jupiter atmospheres (51 Peg b, tau Boo b, HD 209458 b), in which we have searched for the radial velocity signature of water, methane and carbon dioxide molecules in the planetary spectra. We combine these results with previous high spectral resolution detections of carbon monoxide in these hot Jupiter atmospheres to provide constraints on the temperature-pressure profile of the atmospheres, and to determine the relative abundances of the major carbon- and oxygen-bearing species. Preliminary results for 51 Peg b indicate a non-inverted and oxygen-rich atmosphere. I will also highlight how combining spatial information with high resolution spectra allows a similarly robust determination of the chemical composition of planets at large separations (i.e. directly imaged planets), via the detection of carbon monoxide in beta Pic b (Snellen et al. 2014, Nature, embargoed). This novel technique opens up exoplanet atmosphere characterisation at high spectral resolution to a new regime of younger planets and their evolution.