Search for TiO and Optical Nightside Emission from the Exoplanet WASP-33b

Herman, M.; Mooij, Ernst de; Jayawardhana, Ray; Brogi, Matteo

doi:10.3847/1538-3881/ab9e77

Cited by 42 publications

(73 citation statements)

References 55 publications

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“…In addition to our data from CARMENES and HARPS-N, we also re-analyzed five archival observations from ES-PaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada-France-Hawaii telescope (Herman et al 2020). Details of this analysis are provided in Sections 5.5 and 5.6.…”

Section: Observationsmentioning

confidence: 99%

“…However, the line lists of TiO suffer from inaccuracies, which reduce the detection sensitivity of the molecule (Hoeijmakers et al 2015;Nugroho et al 2017). The calculation of models leading to a detection of TiO in planetary atmospheres remains a challenging task (Herman et al 2020;Serindag et al 2021). We attempted to mitigate this issue by using the new line database ToTo ExoMol (McKemmish et al 2019) to generate our TiO model spectrum.…”

Section: Exclusion Of Bad Spectral Ordersmentioning

confidence: 99%

“…High-resolution Doppler spectroscopy led to the detection of TiO in the emission spectrum of WASP-33b (Nugroho et al 2017). However, Herman et al (2020) reported a non-detection of TiO at high spectral resolution. More recently, Serindag et al (2021) reassessed the presence of TiO in the spectra from Nugroho et al (2017) by using an improved TiO line list, but they could not find a detection at the same orbital parameters as the previous work.…”

Section: Introductionmentioning

confidence: 99%

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Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

Cont

Yan

Reiners

et al. 2021

A&A

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Context. Theoretical studies predict the presence of thermal inversions in the atmosphere of highly irradiated gas giant planets. Recent observations have identified these inversion layers. However, the role of different chemical species in their formation remains unclear. Aims. We search for the signature of the thermal inversion agents TiO and Fe in the dayside emission spectrum of the ultra-hot Jupiter WASP-33b. Methods. The spectra were obtained with CARMENES and HARPS-N, covering different wavelength ranges. Telluric and stellar absorption lines were removed with SYSREM. We cross-correlated the residual spectra with model spectra to retrieve the signals from the planetary atmosphere. Results. We find evidence for TiO at a significance of 4.9σ with CARMENES. The strength of the TiO signal drops close to the secondary eclipse. No TiO signal is found with HARPS-N. An injection-recovery test suggests that the TiO signal is below the detection level at the wavelengths covered by HARPS-N. The emission signature of Fe is detected with both instruments at significance levels of 5.7σ and 4.5σ, respectively. By combining all observations, we obtain a significance level of 7.3σ for Fe. We find the TiO signal at Kp = 248.0−2.5+2.0 km s−1, which is in disagreement with the Fe detection at Kp = 225.0−3.5+4.0 km s−1. The Kp value for Fe is in agreement with prior investigations. The model spectra require different temperature profiles for TiO and Fe to match the observations. We observe a broader line profile for Fe than for TiO. Conclusions. Our results confirm the existence of a temperature inversion layer in the planetary atmosphere. The observed Kp offset and different strengths of broadening in the line profiles suggest the existence of a TiO-depleted hot spot in the planetary atmosphere.

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Section: Observationsmentioning

confidence: 99%

Section: Exclusion Of Bad Spectral Ordersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

Cont

Yan

Reiners

et al. 2021

A&A

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“…High-resolution spectroscopy has also provided detections of Fe , Fe , Ca , Ca , Mg , Cr and the Balmer series of hydrogen in the UHJ KELT-20b/MASCARA-2b (Casasayas-Barris et al 2018Nugroho et al 2020a;Hoeĳmakers et al 2020a;Stangret et al 2020). High-resolution explorations of the UHJ WASP-33b revealed signs of TiO (Nugroho et al 2017), Fe (Nugroho et al 2020b), andCa (Yan et al 2019), though TiO was not detected in later observations by Herman et al (2020). A search for FeH in several hot Jupiters resulted in tentative evidence for its presence in WASP-33b and KELT-20b/MASCARA-2b (Kesseli et al 2020).…”

Section: Introductionmentioning

confidence: 99%

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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“…This is both the first high-resolution TiO or VO detection and the first high-resolution detection of a thermal inversion. However, Herman et al (2020) analyzed similar quality high-resolution optical transmission and dayside spectra of WASP-33b taken with the Canada-France-Hawaii Telescope (CFHT) and do not detect a TiO signal. More recently, Nugroho et al (2020) have detected Fe I emission from WASP-33b in the same Subaru data and suggest neutral iron may also contribute to driving the inversion.…”

Section: Introductionmentioning

confidence: 99%

Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol TOTO line list

Serindag

Nugroho

Mollière

et al. 2021

A&A

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Context. Efficient absorption of stellar ultraviolet and visible radiation by TiO and VO is predicted to drive temperature inversions in the upper atmospheres of hot Jupiters. However, very few inversions or detections of TiO or VO have been reported, and results are often contradictory. Aims. Using the improved ExoMol Toto line list, we searched for TiO emission in the dayside spectrum of WASP-33b using the same data in which the molecule was previously detected with an older line list at 4.8σ. We intended to confirm the molecular detection and quantify the signal improvement offered by the ExoMol Toto line list. Methods. Data from the High Dispersion Spectrograph on the Subaru Telescope was extracted and reduced in an identical manner to the previous study. Stellar and telluric contamination were then removed. High-resolution TiO emission models of WASP-33b were created that spanned a range of molecular abundances using the radiative transfer code petitRADTRANS, and were subsequently cross-correlated with the data. Results. We measure a 4.3σ TiO emission signature using the ExoMol Toto models, corresponding to a WASP-33b orbital velocity semi-amplitude of K p = 252.9 +5.0 −5.3 km s −1 and a system velocity of v sys = −23.0 +4.7 −4.6 km s −1. Injection-recovery tests using models based on the new and earlier line lists indicate that if the new models provide a perfect match to the planet spectrum, the significance of the TiO detection should have increased by a factor of ∼2. Conclusions. Although the TiO signal we find is statistically significant, comparison with previous works makes our result too ambiguous to claim a clear-cut detection. Unexpectedly, the new ExoMol Toto models provide a weaker signal than that found previously, which is offset in K p-v sys space. This sheds some doubt on both detections, especially in light of a recently published TiO non-detection using a different dataset.

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Search for TiO and Optical Nightside Emission from the Exoplanet WASP-33b

Cited by 42 publications

References 55 publications

Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

Detection of Fe and evidence for TiO in the dayside emission spectrum of WASP-33b

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

Is TiO emission present in the ultra-hot Jupiter WASP-33b? A reassessment using the improved ExoMol TOTO line list

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