2021AJ....161..278W -
Astron. J., 161, 278-278 (2021/June-0)
ACCESS: an optical transmission spectrum of the high-gravity hot Jupiter HAT-P-23b.
WEAVER I.C., LOPEZ-MORALES M., ALAM M.K., ESPINOZA N., RACKHAM B.V., GOYAL J.M., MacDONALD R.J., LEWIS N.K., APAI D., BIXEL A., JORDAN A., KIRK J., McGRUDER C. and OSIP D.J.
Abstract (from CDS):
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.
Abstract Copyright:
© 2021. The American Astronomical Society. All rights reserved.
Journal keyword(s):
Exoplanet atmospheres - Stellar activity - Starspots - Transmission spectroscopy
Simbad objects:
7
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