ACCESS: An optical transmission spectrum of the high-gravity hot jupiter HAT-P-23b

Ian C. Weaver, Mercedes López-Morales, Munazza K. Alam, Néstor Espinoza, Benjamin V. Rackham, Jayesh M. Goyal, Ryan J. MacDonald, Nikole K. Lewis, Dániel Apai, Alex Bixel, Andrés Jordán, James Kirk, Chima McGruder, David J. Osip

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9 Citas (Scopus)

Resumen

We present a new ground-based visible transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b, obtained as part of the ACCESS project. We derive the spectrum from five transits observed between 2016 and 2018, with combined wavelength coverage between 5200 Å and 9269 Å in 200 Å bins, and with a median precision of 247 ppm per bin. HAT-P-23b’s relatively high surface gravity (g ≈ 30 m s−2), combined with updated stellar and planetary parameters from Gaia DR2, gives a five-scale-height signal of 384 ppm for a hydrogen-dominated atmosphere. Bayesian models favor a clear atmosphere for the planet with the tentative presence of TiO, after simultaneously modeling stellar contamination, using spots parameter constraints from photometry. If confirmed, HAT-P-23b would be the first example of a high-gravity gas giant with a clear atmosphere observed in transmission at optical/near-IR wavelengths; therefore, we recommend expanding observations to the UV and IR to confirm our results and further characterize this planet. This result demonstrates how combining transmission spectroscopy of exoplanet atmospheres with long-term photometric monitoring of the host stars can help disentangle the exoplanet and stellar activity signals.

Idioma originalInglés
Número de artículo278
PublicaciónAstronomical Journal
Volumen161
N.º6
DOI
EstadoPublicada - jun. 2021
Publicado de forma externa

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