TY - JOUR
T1 - ACCESS
T2 - An optical transmission spectrum of the high-gravity hot jupiter HAT-P-23b
AU - Weaver, Ian C.
AU - López-Morales, Mercedes
AU - Alam, Munazza K.
AU - Espinoza, Néstor
AU - Rackham, Benjamin V.
AU - Goyal, Jayesh M.
AU - MacDonald, Ryan J.
AU - Lewis, Nikole K.
AU - Apai, Dániel
AU - Bixel, Alex
AU - Jordán, Andrés
AU - Kirk, James
AU - McGruder, Chima
AU - Osip, David J.
N1 - Publisher Copyright: © 2021. The American Astronomical Society. All rights reserved.
PY - 2021/6
Y1 - 2021/6
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85106620710&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85106620710&partnerID=8YFLogxK
U2 - 10.3847/1538-3881/abf652
DO - 10.3847/1538-3881/abf652
M3 - Article
SN - 0004-6256
VL - 161
JO - Astronomical Journal
JF - Astronomical Journal
IS - 6
M1 - 278
ER -