Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

Merritt, Stephanie; Gibson, Neale P.; Nugroho, Stevanus K.; Mooij, Ernst de; Hooton, Matthew J.; Matthews, S. M.; McKemmish, Laura K.; Evans, T. M.; Nikolov, Nikolay; Sing, David K.; Spake, Jessica; Watson, C. A.

doi:10.1051/0004-6361/201937409

Cited by 88 publications

(105 citation statements)

References 142 publications

(300 reference statements)

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“…In order to confirm and expand upon previous detections, we present an atomic species inventory of the ultra-hot Jupiter WASP-121b, using high-resolution spectra taken with VLT/UVES (Dekker et al 2000), an instrument which has seen successful use for the exploration of exoplanet atmospheres (Snellen 2004;Khalafinejad et al 2017;Gibson et al 2019). The blue arm of these observations was previously explored by (Gibson et al 2020), and analysis of the red arm in a search for molecular features was presented in Merritt et al (2020): this paper presents analysis of both the red and blue arms combined with the aim of searching for a broad range of species. In Sec.…”

Section: Introductionmentioning

confidence: 73%

“…At high resolution, a search for TiO or VO in the transmission spectrum of WASP-121b using UVES (UV-Visual Echelle Spectrograph) on the VLT failed to detect either (Merritt et al 2020), in conflict with earlier low-resolution work (Evans et al 2016(Evans et al , 2018Tsiaras et al 2018), though the inaccuracy of the VO high-temperature line-list was cited as a possible cause for the nondetection of VO. Analysis by Gibson et al (2020) of the same UVES transits, and by Bourrier et al (2020a) and Cabot et al (2020) using HARPS (High-Accuracy Radial-velocity Planet Searcher) on La Silla, have detected Fe deeper in the atmosphere, with Cabot et al (2020) additionally detecting the presence of H .…”

Section: Introductionmentioning

confidence: 80%

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An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy

Merritt

Gibson

Nugroho

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Ultra-hot Jupiters (UHJs) present excellent targets for atmospheric characterisation. Their hot dayside temperatures (T ≳ 2200 K) strongly suppress the formation of condensates, leading to clear and highly-inflated atmospheres extremely conducive to transmission spectroscopy. Recent studies using optical high-resolution spectra have discovered a plethora of neutral and ionised atomic species in UHJs, placing constraints on their atmospheric structure and composition. Our recent work has presented a search for molecular features and detection of Fe i in the UHJ WASP-121b using VLT/UVES transmission spectroscopy. Here, we present a systematic search for atomic species in its atmosphere using cross-correlation methods. In a single transit, we uncover potential signals of 17 atomic species which we investigate further, categorising 5 as strong detections, 3 as tentative detections, and 9 as weak signals worthy of further exploration. We confirm previous detections of Cr i, V i, Ca i, K i and exospheric H i and Ca ii made with HARPS and ESPRESSO, and independently re-recover our previous detection of Fe i at 8.8 σ using both the blue and red arms of the UVES data. We also add a novel detection of Sc ii at 4.2 σ. Our results further demonstrate the richness of UHJs for optical high-resolution spectroscopy.

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 80%

An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy

Merritt

Gibson

Nugroho

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…However, there is an ongoing debate about the role of TiO/VO in atmospheres with particularly large day-night temperature contrasts. Although previous studies have shown that these compounds are likely to be thermally dissociated on the hotter day-side, specifically for WASP-121b which has a similar (albeit slightly cooler) P -T structure than WASP-12b (Parmentier et al 2018), they may condense out of the night-side atmosphere entirely (Parmentier et al 2018;Merritt et al 2020). Furthermore, both TiO and VO are currently very difficult to detect directly (Mikal-Evans et al 2020), as this would require high resolution observations in the near-UV/optical range.…”

Section: Effects Of Tio and Vomentioning

confidence: 99%

Pseudo-2D modelling of heat redistribution through H2 thermal dissociation/recombination: consequences for ultra-hot Jupiters

Roth

Drummond

Hébrard

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Thermal dissociation and recombination of molecular hydrogen, H2, in the atmospheres of ultra-hot Jupiters (UHJs) has been shown to play an important role in global heat redistribution. This, in turn, significantly impacts their planetary emission, yet only limited investigations on the atmospheric effects have so far been conducted. Here we investigate the heat redistribution caused by this dissociation/recombination reaction, alongside feedback mechanisms between the atmospheric chemistry and radiative transfer, for a planetary and stellar configuration typical of UHJs. To do this, we have developed a time-dependent pseudo-2D model, including a treatment of time-independent equilibrium chemical effects. As a result of the reaction heat redistribution, we find temperature changes of up to ∼400 K in the atmosphere. When TiO and VO are additionally considered as opacity sources, these changes in temperature increase to over ∼800 K in some areas. This heat redistribution is found to significantly shift the region of peak atmospheric temperature, or hotspot, towards the evening terminator in both cases. The impact of varying the longitudinal wind speed on the reaction heat distribution is also investigated. When excluding TiO/VO, increased wind speeds are shown to increase the impact of the reaction heat redistribution up to a threshold wind speed. When including TiO/VO there is no apparent wind speed threshold, due to thermal stabilisation by these species. We also construct pseudo-2D phase curves from our model, and highlight both significant spectral flux damping and increased phase offset caused by the reaction heat redistribution.

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“…This agrees with the work of Fortney et al (2008), which postulated that the presence of optical absorbers would lead to, and require, large day-night temperature contrasts. However, Merritt et al (2020) used highresolution ground-based observations to place limits on the maximum abundances of TiO and VO in the terminator of WASP-121 b to log(TiO)<−9.26 and log(VO)<−7.88. Nevertheless the authors of this study note that these upper bounds are degenerate with the cloud deck and scattering properties while also being limited by the accuracy of the VO line lists.…”

Section: Previous Claims Of Optical Absorbersmentioning

confidence: 99%

ARES I: WASP-76 b, A Tale of Two HST Spectra*

Edwards

Changeat

Baeyens

et al. 2020

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We analyze the transmission and emission spectra of the ultra-hot Jupiter WASP-76 b, observed with the G141 grism of the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3). We reduce and fit the raw data for each observation using the open-source software Iraclis before performing a fully Bayesian retrieval using the publicly available analysis suite TauREx 3. Previous studies of the WFC3 transmission spectra of WASP-76 b found hints of titanium oxide (TiO) and vanadium oxide (VO) or non-gray clouds. Accounting for a fainter stellar companion to WASP-76, we reanalyze this data and show that removing the effects of this background star changes the slope of the spectrum, resulting in these visible absorbers no longer being detected, eliminating the need for a non-gray cloud model to adequately fit the data but maintaining the strong water feature previously seen. However, our analysis of the emission spectrum suggests the presence of TiO and an atmospheric thermal inversion, along with a significant amount of water. Given the brightness of the host star and the size of the atmospheric features, WASP-76 b is an excellent target for further characterization with HST, or with future facilities, to better understand the nature of its atmosphere, to confirm the presence of TiO and to search for other optical absorbers.

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Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

Cited by 88 publications

References 142 publications

An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy

An inventory of atomic species in the atmosphere of WASP-121b using UVES high-resolution spectroscopy

Pseudo-2D modelling of heat redistribution through H2 thermal dissociation/recombination: consequences for ultra-hot Jupiters

ARES I: WASP-76 b, A Tale of Two HST Spectra*

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