HD 179949b: A close orbiting extrasolar giant planet with a stratosphere?

J. R. Barnes, Travis S. Barman, H. R.A. Jones, C. J. Leigh, A. Collier Cameron, R. J. Barber, D. J. Pinfield

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

We have carried out a search for the 2.14-μm spectroscopic signature of the close orbiting extrasolar giant planet, HD 179949b. High-cadence time-series spectra were obtained with the Cryogenic high-resolution InfraRed Échelle Spectrograph at Very Large Telescope, Unit 1 on two closely separated nights. Deconvolution yielded spectroscopic profiles with mean signal-to-noise ratios of several thousand, enabling the near-infrared contrast ratios predicted for the HD 179949 system to be achieved. Recent models have predicted that the hottest planets may exhibit spectral signatures in emission due to the presence of TiO and VO which may be responsible for a temperature inversion high in the atmosphere. We have used our phase-dependent orbital model and tomographic techniques to search for the planetary signature under the assumption of an absorption line dominated atmospheric spectrum, where T and V are depleted from the atmospheric model, and an emission line dominated spectrum, where TiO and VO are present. We do not detect a planet in either case, but the 2.120-2.174-μm wavelength region covered by our observations enables the deepest near-infrared limits yet to be placed on the planet/star contrast ratio of any close orbiting extrasolar giant planet system. We are able to rule out the presence of an atmosphere dominated by absorption opacities in the case of HD 179949b at a contrast ratio of Fp/F* ∼ 1/3350, with 99 per cent confidence.

Original languageEnglish (US)
Pages (from-to)1258-1266
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume390
Issue number3
DOIs
StatePublished - Nov 2008

Keywords

  • Line: profiles
  • Methods: data analysis
  • Planetary systems
  • Stars: individual: HD 179949
  • Stars: late-type
  • Techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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