ExoGemS high-resolution transmission spectroscopy of WASP-76b with GRACES

Emily K. Deibert*, Ernst J. W. de Mooij, Ray Jayawardhana, Jake D. Turner, Andrew Ridden-Harper, Callie E. Hood, Jonathan J. Fortney, Laura Flagg, Luca Fossati, Romain Allart, Matteo Brogi, Ryan J. MacDonald

*Corresponding author for this work

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3 Citations (Scopus)
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We present high-resolution transmission spectroscopy of WASP-76b with Gemini Remote Access to CFHT ESPaDOnS Spectrograph (GRACES)/Gemini North obtained as part of the ExoGemS survey. With a broad spectral range of 400–1050 nm and a relatively high resolution of ∼66,000, these observations are particularly well suited to searching for atomic and molecular atmospheric species via the Doppler cross-correlation technique. We recover absorption features due to neutral iron (Fe i), sodium (Na i), and ionized calcium (Ca ii) at high significance (>5σ), and investigate possible atmospheric temperatures and wind speeds. We also report tentative (>3σ) detections of Li i, K i, Cr i, and V i in the atmosphere of WASP-76b. Finally, we report nondetections of a number of other species, some of which have previously been detected with other instruments. Through model injection/recovery tests, we demonstrate that many of these species are not expected to be detected in our observations. These results allow us to place GRACES and the ExoGemS survey in context with other high-resolution optical spectrographs.
Original languageEnglish
Article number141
JournalAstronomical Journal
Issue number4
Early online date04 Sept 2023
Publication statusPublished - 01 Oct 2023


  • Exoplanets
  • Exoplanet atmospheric dynamics
  • Extrasolar gaseous giant planets
  • Exoplanet atmospheric composition
  • Hot Jupiters
  • Transmission spectroscopy
  • Exoplanet atmospheres


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