The PEPSI Exoplanet Transit Survey (PETS). II. A Deep Search for Thermal Inversion Agents in KELT-20 b/MASCARA-2 b with Emission and Transmission Spectroscopy

Abstract

Recent observations have shown that the atmospheres of ultra hot Jupiters (UHJs) commonly possess temperature inversions, where the temperature increases with increasing altitude. Nonetheless, which opacity sources are responsible for the presence of these inversions remains largely observationally unconstrained. We used LBT/PEPSI to observe the atmosphere of the UHJ KELT-20 b in both transmission and emission in order to search for molecular agents which could be responsible for the temperature inversion. We validate our methodology by confirming previous detections of Fe I in emission at $16.9\sigma$. Our search for the inversion agents TiO, VO, FeH, and CaH results in non-detections. Using injection-recovery testing we set $4\sigma$ upper limits upon the volume mixing ratios for these constituents as low as $\sim 1\times 10^{-9}$ for TiO. For TiO, VO, and CaH, our limits are much lower than expectations from an equilibrium chemical model, while we cannot set constraining limits on FeH with our data. We thus rule out TiO and CaH as the source of the temperature inversion in KELT-20 b, and VO only if the line lists are sufficiently accurate.

18 pages, 11 figures. Accepted for publication in AJ

References in corpus (45)

• The NumPy array: a structure for efficient numerical computation
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• petitRADTRANS: a Python radiative transfer package for exoplanet characterization and retrieval
• On the radiative equilibrium of irradiated planetary atmospheres
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• Can TiO Explain Thermal Inversions in the Upper Atmospheres of Irradiated Giant Planets?
• An ultrahot gas-giant exoplanet with a stratosphere
• ExoMol line lists XVIII. The high temperature spectrum of VO
• Methane, Carbon Monoxide, and Ammonia in Brown Dwarfs and Self-Luminous Giant Planets
• PEPSI: The high-resolution echelle spectrograph and polarimeter for the Large Binocular Telescope
• Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) IV. A spectral inventory of atoms and molecules in the high-resolution transmission spectrum of WASP-121 b
• High-Resolution Spectroscopic Detection of TiO and Stratosphere in the Day-side of WASP-33b
• A Comparative Study of Atmospheric Chemistry with VULCAN
• Neutral Iron Emission Lines From The Day-side Of KELT-9b -- The GAPS Programme With HARPS-N At TNG XX
• Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets
• Titanium oxide and chemical inhomogeneity in the atmosphere of the exoplanet WASP-189b
• ESPRESSO high resolution transmission spectroscopy of WASP-76b
• KELT-20b: A giant planet with a period of P~ 3.5 days transiting the V~ 7.6 early A star HD 185603
• Evidence for a Dayside Thermal Inversion and High Metallicity for the Hot Jupiter WASP-18b
• An Atomic Spectral Survey of WASP-76b: Resolving Chemical Gradients and Asymmetries
• New Avenues for Thermal Inversions in hot Jupiters
• A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b
• ARES I: WASP-76 b, A Tale of Two HST Spectra
• Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b
• A transition between the hot and the ultra-hot Jupiter atmospheres
• An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy
• High-resolution Transmission Spectroscopy of MASCARA-2 b with EXPRES
• Visible-light Phase Curves from the Second Year of the TESS Primary Mission
• Spatially-resolving the terminator: Variation of Fe, temperature and winds in WASP-76 b across planetary limbs and orbital phase
• High-resolution transmission spectroscopy study of ultra-hot Jupiters HAT-P-57b, KELT-17b, KELT-21b, KELT-7b, MASCARA-1b, and WASP-189b
• Detection of iron emission lines and a temperature inversion on the dayside of the ultra-hot Jupiter KELT-20b
• The Hubble WFC3 Emission Spectrum of the Extremely-Hot Jupiter, KELT-9b
• Detection of CO emission lines in the dayside atmospheres of WASP-33b and WASP-189b with GIANO
• Silicon in the dayside atmospheres of two ultra-hot Jupiters
• Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol Toto line list
• The PEPSI Exoplanet Transit Survey (PETS) I: Investigating the presence of a silicate atmosphere on the super-Earth 55 Cnc e
• Search for TiO and Optical Night-side Emission from the Exoplanet WASP-33b
• Strong H${}_2$O and CO emission features in the spectrum of KELT-20b driven by stellar UV irradiation
• Exoplanet atmospheres at high resolution through a modest-size telescope. Fe II in MASCARA-2b and KELT-9b with FIES on the Nordic Optical Telescope
• Unifying High- and Low-resolution Observations to Constrain the Dayside Atmosphere of KELT-20b/MASCARA-2b
• The GAPS Programme at TNG XXXIII. HARPS-N detects multiple atomic species in emission from the dayside of KELT-20b
• A quantitative assessment of the VO line list: Inaccuracies hamper high-resolution VO detections in exoplanet atmospheres
• Automatic Spectroscopic Data Reduction using BANZAI
• TOI-1518b: A Misaligned Ultra-hot Jupiter with Iron in its Atmosphere
• Day-side Fe I Emission, Day-Night Brightness Contrast and Phase Offset of the Exoplanet WASP-33b

Cited by in corpus (14)

• Retrieval survey of metals in six ultra-hot Jupiters: Trends in chemistry, rain-out, ionisation and atmospheric dynamics
• CRIRES+ detection of CO emissions lines and temperature inversions on the dayside of WASP-18b and WASP-76b
• Keck/KPIC Emission Spectroscopy of WASP-33b
• The GAPS programme at TNG. XLV. HI Balmer lines transmission spectroscopy and NLTE atmospheric modelling of the ultra-hot Jupiter KELT-20b/MASCARA-2b
• The PEPSI Exoplanet Transit Survey. III: The detection of FeI, CrI and TiI in the atmosphere of MASCARA-1 b through high-resolution emission spectroscopy
• The GAPS programme at TNG: TBD. Studies of atmospheric FeII winds in ultra-hot Jupiters KELT-9b and KELT-20b using HARPS-N spectrograph
• Retrieving day- and nightside atmospheric properties of the ultra-hot Jupiter TOI-2109b. Detection of Fe and CO emission lines and evidence for inefficient heat transport
• Strong NUV Refractory Absorption and Dissociated Water in the Hubble Transmission Spectrum of the Ultra Hot Jupiter KELT-20 b
• TOI-2005b: An Eccentric Warm Jupiter in Spin-Orbit Alignment
• NLTE atmospheric modelling of the ultra-hot Jupiter WASP-178b and comparison with UV and optical observations
• PEPSI Investigation, Retrieval, and Atlas of Numerous Giant Atmospheres (PIRANGA). III. Composition and winds in the atmosphere of TOI-1518 b
• Open Source High-Resolution Exoplanet Atmosphere Retrievals with POSEIDON
• PEPSI Investigation, Retrieval, and Atlas of Numerous Giant Atmospheres (PIRANGA). IV. High-Resolution Phased-Resolved Spectroscopy of The Ultra Hot Jupiter KELT-20 b
• The breaking of cold traps and onset of titanium in ultra-hot Jupiter atmospheres: WASP-189b in context