Rayleigh scattering in the transmission spectrum of HAT-P-18b

J. Kirk; P. J. Wheatley; T. Louden; A. P. Doyle; I. Skillen; J. McCormac; P. G. J. Irwin; R. Karjalainen

doi:10.1093/mnras/stx752

Rayleigh scattering in the transmission spectrum of HAT-P-18b

Earth and Planetary Astrophysics 2017-04-25 v2

Authors: J. Kirk , P. J. Wheatley , T. Louden , A. P. Doyle , I. Skillen , J. McCormac , P. G. J. Irwin , R. Karjalainen

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Abstract

We have performed ground-based transmission spectroscopy of the hot Jupiter HAT-P-18b using the ACAM instrument on the William Herschel Telescope (WHT). Differential spectroscopy over an entire night was carried out at a resolution of $R \approx 400$ using a nearby comparison star. We detect a bluewards slope extending across our optical transmission spectrum which runs from 4750 to 9250\AA. The slope is consistent with Rayleigh scattering at the equilibrium temperature of the planet (852K). We do not detect enhanced sodium absorption, which indicates that a high-altitude haze is masking the feature and giving rise to the Rayleigh slope. This is only the second discovery of a Rayleigh scattering slope in a hot Jupiter atmosphere from the ground, and our study illustrates how ground-based observations can provide transmission spectra with precision comparable to the Hubble Space Telescope.

Keywords

Rayleigh scattering transmission spectrum hot Jupiter exoplanet atmosphere ground-based observation

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@article{arxiv.1611.06916,
  title  = {Rayleigh scattering in the transmission spectrum of HAT-P-18b},
  author = {J. Kirk and P. J. Wheatley and T. Louden and A. P. Doyle and I. Skillen and J. McCormac and P. G. J. Irwin and R. Karjalainen},
  journal= {arXiv preprint arXiv:1611.06916},
  year   = {2017}
}

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11 pages, 9 figures, accepted for publication in MNRAS

Rayleigh scattering in the transmission spectrum of HAT-P-18b

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