A cautionary tale: limitations of a brightness-based spectroscopic approach to chromatic exoplanet radii

H. M. Cegla, C. Lovis, V. Bourrier, C. A. Watson, A. Wyttenbach

Research output: Contribution to journalArticle

3 Citations (Scopus)
174 Downloads (Pure)

Abstract

Determining wavelength-dependent exoplanet radii measurements is an excellent way to probe the composition of exoplanet atmospheres. In light of this, Borsa et al. (2016) sought to develop a technique to obtain such measurements by comparing ground-based transmission spectra to the expected brightness variations during an exoplanet transit. However, we demonstrate herein that this is not possible due to the transit light curve normalisation necessary to remove the effects of the Earth's atmosphere on the ground-based observations. This is because the recoverable exoplanet radius is set by the planet-to-star radius ratio within the transit light curve; we demonstrate this both analytically and with simulated planet transits, as well as through a reanalysis of the HD 189733 b data.
Original languageEnglish
Article numberL3
Number of pages5
JournalAstronomy & Astrophysics
Volume598
Early online date26 Jan 2017
DOIs
Publication statusPublished - Feb 2017

Keywords

  • methods: data analysis
  • planets and satellites: atmospheres
  • planets and satellites: fundamental parameters
  • planets and satellites: individual: HD 189733 b
  • techniques: radial velocities
  • techniques: spectroscopic

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