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 - Funding Information:
We thank the anonymous referee and data editor for helpful comments and feedback. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. We thank Jennifer Fienco, the Las Campanas Observatory staff, and the observing personnel for providing the facilities and guidance necessary for making the collection of this high-quality data set possible. This research has made use of the VizieR catalog access tool, CDS, Strasbourg, France (Ochsenbein et al. 2000). A.J. acknowledges support from ANID—Millennium Science Initiative— ICN12_009. The results reported herein benefited from collaborations and/or information exchange within NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA’s Science Mission Directorate, and funding through the NExSS Earths in Other Solar Systems (PI: Apai) and ACCESS (PI: López-Morales) teams. I.C.W. and M.L.M. thank the Brinson Foundation for supporting this project. B.V.R. thanks the Heising-Simons Foundation for support. This research used computing resources from the Smithsonian Institution High Performance Cluster (SI/HPC).
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
U2 - 10.3847/1538-3881/abf652
DO - 10.3847/1538-3881/abf652
M3 - Article
AN - SCOPUS:85106620710
SN - 0004-6256
VL - 161
JO - Astronomical Journal
JF - Astronomical Journal
IS - 6
M1 - 278
ER -