NOAO >   Observing Info >   Approved Programs >   2012A-0484

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Proposal Information for 2012A-0484


PI: Simon Schuler, NOAO, sschuler@noao.edu
Address: 950 N Cherry Ave, Tucson, AZ 85719, USA

CoI: Johanna Teske, University of Arizona, Steward Observatory
CoI: Katia Cunha, NOAO
CoI: Caitlin Griffith, Unversity of Arizona, Lunar Planetary Lab
CoI: Verne Smith, NOAO

Title: C/O Ratios of Stars with Transiting Hot Jupiters: Connecting Stars to Planets

Abstract: A planet's C/O ratio reveals information about its formation and evolution, with a C/O>0.8 resulting in a C-dominated interior versus the Si-dominated composition of Earth. Close-in giant planets likely formed in the outer protoplanetary disk from icy planetesimals that coalesced to form the core, followed by gas accretion and inward migration; thus the predefined initial gas composition-that of the star-should also be reflected in the planet. While most exoplanet models assume a solar C/O ratio and an O-rich planet composition, relaxing this leads to drastic differences in the planet-low atmospheric abundance of the normally-dominant H_2O; atmospheric oxygen concentration in CO versus H_2O; interiors dominated by C- rich compounds like silicate, graphite, and diamond; and photochemical production of hydrocarbon chains. Recent results suggest a C/O>=1 in the atmosphere of one of the most highly irradiated exoplanets, WASP- 12b; this is particularly peculiar given the host star's C/O~0.40, and introduces the possibility of a sample of \textitcarbon-rich exoplanets. It raises the question, `Are exoplanets and their host stars comprised of the same material, and if not, what makes them different?' This proposal aims to address that question by obtaining a uniform sample of stellar C/O ratios for the most highly-studied exoplanet host stars, in order to investigate the connection between star and planet compositions.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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