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arXiv · 2106.14808

Transmission spectroscopy with VLT FORS2: a featureless spectrum for the low-density transiting exoplanet WASP-88b

Petros Spyratos·Nikolay Nikolov·John Southworth·Savvas Constantinou·Nikku Madhusudhan·Aarynn L. Carter·Ernst J. W. de Mooij·Jonathan J. Fortney·Neale P. Gibson·Jayesh M. Goyal·Christiane Helling·Nathan J. Mayne·Thomas Mikal-Evans
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Abstract

We present ground-based optical transmission spectroscopy of the low-density hot Jupiter WASP-88b covering the wavelength range 4413-8333 {\AA} with the FORS2 spectrograph on the Very Large Telescope. The FORS2 white light curves exhibit a significant time-correlated noise which we model using a Gaussian Process and remove as a wavelength-independent component from the spectroscopic light curves. We analyse complementary photometric observations from the Transiting Exoplanet Survey Satellite and refine the system properties and ephemeris. We find a featureless transmission spectrum with increased absorption towards shorter wavelengths. We perform an atmospheric retrieval analysis with the AURA code, finding tentative evidence for haze in the upper atmospheric layers and a lower likelihood for a dense cloud deck. Whilst our retrieval analysis results point toward clouds and hazes, further evidence is needed to definitively reject a clear-sky scenario.

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Petros Spyratos, Nikolay Nikolov, John Southworth, Savvas Constantinou, Nikku Madhusudhan, Aarynn L. Carter, Ernst J. W. de Mooij, Jonathan J. Fortney, Neale P. Gibson, Jayesh M. Goyal, Christiane Helling, Nathan J. Mayne, Thomas Mikal-Evans. 2021-06-28. Transmission spectroscopy with VLT FORS2: a featureless spectrum for the low-density transiting exoplanet WASP-88b. https://doi.org/10.1093/mnras/stab1847

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