A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b

Yan, F.; Πάλλη, Ε.; Reiners, A.; Molaverdikhani, Karan; Casasayas-Barris, N.; Nortmann, L.; Chen, G.; Mollière, P.; Stangret, M.

doi:10.1051/0004-6361/202038294

Cited by 71 publications

(124 citation statements)

References 66 publications

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“…The search for TiO/VO in the optical transmission spectroscopy remains unresolved. An alternative explanation is that Fe is responsible for the thermal inversion, a claim that is gaining support with the recent detection of Fe I in the emission spectra of two UHJs, KELT-9 b (Pino et al 2020) and WASP-189 b (Yan et al 2020).…”

Section: Introductionmentioning

confidence: 93%

Obliquity measurement and atmospheric characterisation of the WASP-74 planetary system

Luque

Casasayas-Barris

Parviainen

et al. 2020

A&A

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We present new transit observations of the hot Jupiter WASP-74 b (Teq ~ 1860 K) using the high-resolution spectrograph HARPS-N and the multi-colour simultaneous imager MuSCAT2. We refined the orbital properties of the planet and its host star and measured its obliquity for the first time. The measured sky-projected angle between the stellar spin-axis and the orbital axis of the planet is compatible with an orbit that is well-aligned with the equator of the host star (λ = 0.77 ± 0.99 deg). We are not able to detect any absorption feature of Hα or any other atomic spectral features in the high-resolution transmission spectra of this source owing to low S/N at the line cores. Despite previous claims regarding the presence of strong optical absorbers such as TiO and VO gases in the atmosphere of WASP-74 b, new ground-based photometry combined with a reanalysis of previously reported observations from the literature show a slope in the low-resolution transmission spectrum that is steeper than expected from Rayleigh scattering alone.

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Section: Introductionmentioning

confidence: 93%

Obliquity measurement and atmospheric characterisation of the WASP-74 planetary system

Luque

Casasayas-Barris

Parviainen

et al. 2020

A&A

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“…For TiO, we took the inverted T -p profile found by Haynes et al (2015). To model the Fe spectrum, we used the T -p profile of WASP-189b, which was retrieved by Yan et al (2020) using the Fe emission lines. This planet has properties similar to WASP-33b (e.g., mass, radius, equilibrium temperature, and spectral type of the host star).…”

Section: Spectral Modelsmentioning

confidence: 99%

“…For some planets, the detected spectral lines allowed for properties of their Johnson et al (2015) atmospheres to be analyzed in more detail, including atmospheric mass loss rate (e.g., Yan & Henning 2018;Wyttenbach et al 2020) and nightside condensation (Ehrenreich et al 2020;Kesseli & Snellen 2021). In addition to the transmission spectra, emission features of neutral iron consistent with the presence of an inversion layer were observed in the dayside spectra of the UHJs KELT-9b, WASP-189b, and WASP-33b (Pino et al 2020;Yan et al 2020;Nugroho et al 2020a). These detections of atoms and ions, together with the absence of TiO and VO in the spectra of several UHJs suggest that metals are likely to play a key role in the formation of thermal inversions.…”

Section: Introductionmentioning

confidence: 99%

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

Cont

Yan

Reiners

et al. 2021

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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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“…These thermal spectra exhibit a lack of H 2 O features, which is probably due to thermal dissociation (Parmentier et al 2018). On the other hand, emission spectroscopy with high-resolution spectrographs has revealed the existence of neutral Fe in KELT-9 (Pino et al 2020), WASP-189b (Yan et al 2020), and WASP-33b (Nugroho et al 2020a). In ad-Article number, page 1 of 12 arXiv:2011.07888v1 [astro-ph.EP] 16 Nov 2020…”

Section: Introductionmentioning

confidence: 99%

Detection of the hydrogen Balmer lines in the ultra-hot Jupiter WASP-33b

Yan

Wyttenbach

Casasayas-Barris

et al. 2020

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Ultra-hot Jupiters (UHJs) are highly irradiated giant exoplanets with extremely high day-side temperatures, which lead to thermal dissociation of most of the molecular species. It is expected that the neutral hydrogen atom is one of the main species in the upper atmospheres of ultra-hot Jupiters. Neutral hydrogen has been detected in several UHJs by observing its Balmer line absorption. Here, we report four transit observations of the ultra-hot Jupiter WASP-33b, performed with the CARMENES and HARPS-North spectrographs, and the detection of the Hα, Hβ, and Hγ lines in the planetary transmission spectrum. The combined Hα transmission spectrum of the four transits has an absorption depth of 0.99±0.05 %, which corresponds to an effective radius of 1.31±0.01 R p. The strong Hα absorption indicates that the line probes the high-altitude thermosphere. We further fitted the three Balmer lines using the PAWN model, assuming that the atmosphere is hydrodynamic and in LTE. We retrieved a thermosphere temperature 12200 +1300 −1000 K and a mass-loss rateṀ = 10 11.8 +0.6 −0.5 g s −1. The retrieved large mass-loss rate is compatible with the "Balmer-driven" atmospheric escape scenario, in which the stellar Balmer continua radiation in the near-ultraviolet is substantially absorbed by the excited hydrogen atoms in the planetary thermosphere.

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A temperature inversion with atomic iron in the ultra-hot dayside atmosphere of WASP-189b

Cited by 71 publications

References 66 publications

Obliquity measurement and atmospheric characterisation of the WASP-74 planetary system

Obliquity measurement and atmospheric characterisation of the WASP-74 planetary system

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

Detection of the hydrogen Balmer lines in the ultra-hot Jupiter WASP-33b

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