C/O ratios of stars with transiting hot Jupiter exoplanets

Johanna K. Teske, Katia Cunha, Verne V. Smith, Simon C. Schuler, Caitlin Griffith

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

The relative abundances of carbon and oxygen have long been recognized as fundamental diagnostics of stellar chemical evolution. Now, the growing number of exoplanet observations enable estimation of these elements in exoplanetary atmospheres. In hot Jupiters, the C/O ratio affects the partitioning of carbon in the major observable molecules, making these elements diagnostic of temperature structure and composition. Here we present measurements of carbon and oxygen abundances in 16 stars that host transiting hot Jupiter exoplanets, and we compare our C/O ratios to those measured in larger samples of host stars, as well as those estimated for the corresponding exoplanet atmospheres. With standard stellar abundance analysis we derive stellar parameters as well as [C/H] and [O/H] from multiple abundance indicators, including synthesis fitting of the [O I] λ6300 line and non-LTE corrections for the O I triplet. Our results, in agreement with recent suggestions, indicate that previously measured exoplanet host star C/O ratios may have been overestimated. The mean transiting exoplanet host star C/O ratio from this sample is 0.54 (C/O = 0.54), versus previously measured C/Ohost star means of ∼0.65-0.75. We also observe the increase in C/O with [Fe/H] expected for all stars based on Galactic chemical evolution; a linear fit to our results falls slightly below that of other exoplanet host star studies but has a similar slope. Though the C/O ratios of even the most-observed exoplanets are still uncertain, the more precise abundance analysis possible right now for their host stars can help constrain these planets' formation environments and current compositions.

Original languageEnglish (US)
Article number39
JournalAstrophysical Journal
Volume788
Issue number1
DOIs
StatePublished - Jun 10 2014

Fingerprint

extrasolar planets
Jupiter (planet)
Jupiter
stars
chemical evolution
carbon
oxygen
atmosphere
atmospheres
relative abundance
stellar evolution
galactic evolution
partitioning
planet
suggestion
planets
slopes
synthesis
temperature
molecules

Keywords

  • planets and satellites: formation
  • stars: abundances
  • stars: atmospheres

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

C/O ratios of stars with transiting hot Jupiter exoplanets. / Teske, Johanna K.; Cunha, Katia; Smith, Verne V.; Schuler, Simon C.; Griffith, Caitlin.

In: Astrophysical Journal, Vol. 788, No. 1, 39, 10.06.2014.

Research output: Contribution to journalArticle

Teske, Johanna K. ; Cunha, Katia ; Smith, Verne V. ; Schuler, Simon C. ; Griffith, Caitlin. / C/O ratios of stars with transiting hot Jupiter exoplanets. In: Astrophysical Journal. 2014 ; Vol. 788, No. 1.
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