LBT transmission spectroscopy of HAT-P-12b: confirmation of a cloudy atmosphere with no significant alkali features

Abstract

The hot sub-Saturn-mass exoplanet HAT-P-12b is an ideal target for transmission spectroscopy because of its inflated radius. We observed one transit of the planet with the multi-object double spectrograph (MODS) on the Large Binocular Telescope (LBT) with the binocular mode and obtained an atmosphere transmission spectrum with a wavelength coverage of $\sim$ 0.4 -- 0.9 $\mu$m. The spectrum is relatively flat and does not show any significant sodium or potassium absorption features. Our result is consistent with the revised Hubble Space Telescope (HST) transmission spectrum of a previous work, except that the HST result indicates a tentative detection of potassium. The potassium discrepancy could be the result of statistical fluctuation of the HST dataset. We fit the planetary transmission spectrum with an extensive grid of cloudy models and confirm the presence of high-altitude clouds in the planetary atmosphere. The fit was performed on the combined LBT and HST spectrum, which has an overall wavelength range of 0.4 -- 1.6 $\mu$m. The LBT/MODS spectrograph has unique advantages in transmission spectroscopy observations because it can cover a wide wavelength range with a single exposure and acquire two sets of independent spectra simultaneously.

14 pages, 12 figures. Accepted for publication in Astronomy & Astrophysics

References in corpus (16)

• A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b
• HAT-P-26b: A Neptune-Mass Exoplanet with a Well Constrained Heavy Element Abundance
• Observing transiting planets with JWST -- Prime targets and their synthetic spectral observations
• Detection of titanium oxide in the atmosphere of a hot Jupiter
• HST/STIS Optical Transit Transmission Spectra of the hot-Jupiter HD209458b
• ACCESS I: An Optical Transmission Spectrum of GJ 1214b Reveals a Heterogeneous Stellar Photosphere
• HAT-P-12b: A Low-Density Sub-Saturn Mass Planet Transiting a Metal-Poor K Dwarf
• The Transit Light Source Effect II: The Impact of Stellar Heterogeneity on Transmission Spectra of Planets Orbiting Broadly Sun-like Stars
• HST hot-Jupiter transmission spectral survey: Haze in the atmosphere of WASP-6b
• VLT FORS2 comparative transmission spectroscopy: Detection of Na in the atmosphere of WASP-39b from the ground
• A Cloudiness Index for Transiting Exoplanets Based on the Sodium and Potassium Lines: Tentative Evidence for Hotter Atmospheres Being Less Cloudy at Visible Wavelengths
• VLT/FORS2 comparative transmission spectroscopy II: confirmation of a cloud-deck and Rayleigh scattering in WASP-31b, but no potassium?
• Potassium detection in the clear atmosphere of a hot-Jupiter: FORS2 transmission spectroscopy of WASP-17b
• Signs of strong Na and K absorption in the transmission spectrum of WASP-103b
• Optical to near-infrared transmission spectrum of the warm sub-Saturn HAT-P-12b
• The GTC exoplanet transit spectroscopy survey. VII. An optical transmission spectrum of WASP-48b

Cited by in corpus (19)

• ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations
• Into the Storm: Diving into the winds of the ultra hot Jupiter WASP-76 b with HARPS and ESPRESSO
• ExoClock project II: A large-scale integrated study with 180 updated exoplanet ephemerides
• On The Compatibility of Ground-based and Space-based Data: WASP-96 b, An Example
• ACCESS: Confirmation of a Clear Atmosphere for WASP-96b and a Comparison of Light Curve Detrending Techniques
• ACCESS: Confirmation of no potassium in the atmosphere of WASP-31b
• A new method to measure the spectra of transiting exoplanet atmospheres using multi-object spectroscopy
• A large range of haziness conditions in hot-Jupiter atmospheres
• Transmission spectroscopy with VLT FORS2: a featureless spectrum for the low-density transiting exoplanet WASP-88b
• Understanding Sun-as-a-star variability of solar Balmer lines
• Evidence for stellar contamination in the transmission spectra of HAT-P-12b
• A Population Analysis of 20 Exoplanets Observed from the Optical to the Near-infrared Wavelengths with HST: Evidence for Widespread Stellar Contamination
• ACCESS: Tentative detection of H${}_2$O in the ground-based optical transmission spectrum of the low-density hot Saturn HATS-5b
• A re-analysis of equilibrium chemistry in five hot Jupiters
• Detection of CO${}_2$, CO, and H${}_2$O in the atmosphere of the warm sub-Saturn HAT-P-12b
• Rapid characterization of exoplanet atmospheres with the Exoplanet Transmission Spectroscopy Imager (ETSI)
• Ground-Based Reconnaissance Observations of 21 Exoplanet Atmospheres with the Exoplanet Transmission Spectroscopy Imager
• Information content of JWST transmission spectroscopy of the exoplanet HAT-P-12b from the optical to the mid-infrared
• Low-resolution Transit Spectroscopy of Three Hot Jupiters Using the 2m Himalayan Chandra Telescope