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The GTC exoplanet transit spectroscopy survey. II. An overly large Rayleigh-like feature for exoplanet TrES-3b

Abstract :
Aims: We search for Rayleigh scattering and K and Na absorption signatures from the atmosphere of TrES-3b using ground-based transmission spectroscopy covering the wavelength range from 530 to 950 nm as observed with the OSIRIS instrument at the Gran Telescopio CANARIAS.
Methods: Our analysis is based on a Bayesian approach where the light curves covering a set of given passbands are fitted jointly with PHOENIX-calculated stellar limb darkening profiles. The analysis is carried out assuming both white and red noise that is temporally correlated, with two approaches (Gaussian processes and divide-by-white) to account for the red noise.
Results: An initial analysis reveals a transmission spectrum that shows a strong Rayleigh-like increase in extinction towards the blue end of the spectrum, and enhanced extinction around the K I resonance doublet near 767 nm. However, the signal amplitudes are significantly larger than expected from theoretical considerations. A detailed analysis reveals that the K I-like feature is entirely due to variability in the telluric O2 absorption, but the Rayleigh-like feature remains unexplained.

The light curves are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A114

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Submitted on : Thursday, June 9, 2022 - 11:37:23 AM
Last modification on : Friday, August 5, 2022 - 3:37:49 PM

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H. Parviainen, E. Pallé, L. Nortmann, G. Nowak, N. Iro, et al.. The GTC exoplanet transit spectroscopy survey. II. An overly large Rayleigh-like feature for exoplanet TrES-3b. Astronomy and Astrophysics - A&A, EDP Sciences, 2016, 585, ⟨10.1051/0004-6361/201526313⟩. ⟨insu-03691581⟩

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