HST/STIS transmission spectrum of the ultra-hot Jupiter WASP-76 b confirms the presence of sodium in its atmosphere

Essen, C. von; Mallonn, M.; Hermansen, Stine; Nixon, Matthew C.; Madhusudhan, Nikku; Kjeldsen, H.; Tautvaišienė, G.

doi:10.1051/0004-6361/201937169

Cited by 34 publications

(23 citation statements)

References 74 publications

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“…WASP-76b orbits an F7 V star with m V ≈ 9.5 mag with an orbital period of approximately 1.8 d (West et al 2016;Ehrenreich et al 2020). WASP-76b is an inflated UHJ with roughly one Jupiter mass and twice its radius with an equilibrium temperature of more than 2200 K. Thus, it is a perfect target for atmospheric characterisation given its high equilibrium temperature and the high-metallicity of the host-star (see Seidel et al 2019;Ehrenreich et al 2020;Edwards et al 2020;von Essen et al 2020). We analysed the same data as in Ehrenreich et al (2020) with the objective in mind of exploring which spectral atomic and molecular species can be detected using ESPRESSO.…”

Section: Introductionmentioning

confidence: 99%

ESPRESSO high-resolution transmission spectroscopy of WASP-76 b

Tabernero¹,

Osorio²,

Allart³

et al. 2021

A&A

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Aims. We report on ESPRESSO high-resolution transmission spectroscopic observations of two primary transits of the highly irradiated, ultra-hot Jupiter-sized planet, WASP-76b. We investigated the presence of several key atomic and molecular features of interest that may reveal the atmospheric properties of the planet. Methods. We extracted two transmission spectra of WASP-76b with R ≈ 140 000 using a procedure that allowed us to process the full ESPRESSO wavelength range (3800–7880 Å) simultaneously. We observed that at a high signal-to-noise ratio, the continuum of ESPRESSO spectra shows ‘wiggles’, which are likely caused by an interference pattern outside the spectrograph. To search for the planetary features, we visually analysed the extracted transmission spectra and cross-correlated the observations against theoretical spectra of different atomic and molecular species. Results. The following atomic features are detected: Li I, Na I, Mg I, Ca II, Mn I, K I, and Fe I. All are detected with a confidence level between 9.2 σ (Na I) and 2.8 σ (Mg I). We did not detect the following species: Ti I, Cr I, Ni I, TiO, VO, and ZrO. We impose the following 1 σ upper limits on their detectability: 60, 77, 122, 6, 8, and 8 ppm, respectively. Conclusions. We report the detection of Li I on WASP-76b for the first time. In addition, we confirm the presence of Na I and Fe I as previously reported in the literature. We show that the procedure employed in this work can detect features down to the level of ~0.1% in the transmission spectrum and ~10 ppm by means of a cross-correlation method. We discuss the presence of neutral and singly ionised features in the atmosphere of WASP-76b.

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Section: Introductionmentioning

confidence: 99%

ESPRESSO high-resolution transmission spectroscopy of WASP-76 b

Tabernero¹,

Osorio²,

Allart³

et al. 2021

A&A

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“…These could include modeling various atmospheric scenarios for each planet to judge its suitability for characterization (e.g., Fortenbach & Dressing 2020), performing retrievals on populations of exoplanets (e.g., Changeat et al 2020), classifying groups of planets via color-magnitude diagrams (e.g., Dransfield & Triaud 2020), testing machinelearning techniques for atmospheric retrieval (e.g., Márquez-Neila et al 2018;Hayes et al 2020;, or the exploration of potential biases in current data analysis techniques (e.g., Feng et al 2016;Rocchetto et al 2016;Caldas et al 2019;Changeat et al 2019;Powell et al 2019;MacDonald et al 2020;Taylor et al 2020). Additionally, thorough analyses of Twinkle's capabilities for specific scientific endeavors, such as confirming/refuting the presence of thermal inversions and identifying optical absorbers in ultrahot Jupiters (e.g., Fortney et al 2008;Spiegel et al 2009;Haynes et al 2015;Evans et al 2018;Parmentier et al 2018;Edwards et al 2020;Pluriel et al 2020;von Essen et al 2020;Changeat & Edwards 2021), searching for an exoplanet mass-metallicity trend (e.g., Wakeford et al 2017;Welbanks et al 2019), probing the atmospheres of planets in/close to the radius valley to discern their true nature (e.g., Owen & Wu 2017;Fulton & Petigura 2018;Zeng et al 2019), refining basic planetary and orbital characteristics (e.g., Berardo et al 2019;Dalba & Tamburo 2019;Livingston et al 2019), measuring planet masses through accurate transit timings (e.g., Hadden & Lithwick 2017;Grimm et al 2018;Petigura et al 2018), verifying additional planets within system...…”

Section: Discussionmentioning

confidence: 99%

Terminus: A Versatile Simulator for Space-based Telescopes

Edwards

Stotesbury²

2021

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Space-based telescopes offer unparalleled opportunities for characterizing exoplanets, solar system bodies, and stellar objects. However, observatories in low-Earth orbits (e.g., Hubble, CHaracterising ExOPlanets Satellite, Twinkle, and an ever-increasing number of cubesats) cannot always be continuously pointed at a target due to Earth obscuration. For exoplanet observations consisting of transit, or eclipse, spectroscopy, this causes gaps in the light curve, which reduces the information content and can diminish the science return of the observation. Terminus, a time-domain simulator, has been developed to model the occurrence of these gaps to predict the potential impact on future observations. The simulator is capable of radiometrically modeling exoplanet observations as well as producing light curves and spectra. Here, Terminus is baselined on the Twinkle mission, but the model can be adapted for any space-based telescope and is especially applicable to those in a low-Earth orbit. Terminus also has the capability to model observations of other targets such as asteroids or brown dwarfs.Unified Astronomy Thesaurus concepts: Exoplanet atmospheres (487); Space telescopes (1547); Asteroids (72); Astronomical instrumentation (799); Infrared telescopes (794)

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“…Our chemical model actually suggests a super-solar oxygen abundance to explain the metric in Figure 11. von Essen et al (2020) and Edwards et al (2020) have similarly studied the atmosphere of WASP-76b with HST. Edwards et al (2020) studied both transmission and emission spectra from 1.1 -1.6 µm, and found evidence for both TiO and H 2 O in their fits -albeit with higher TiO abundance (by a factor of 1000) in their emission spectra than in their transmission spectra.…”

Section: Wasp-76bmentioning

confidence: 99%

Tracing bulk elemental ratios in exoplanetary atmospheres with TiO chemistry

Ramírez

Cridland

Mollière

2020

A&A

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Deciphering the bulk elemental abundances of exoplanetary atmospheres is not an easy task, yet it is crucial to understanding the formation history of planets. The purpose of this work is to show that the observability of TiO features at optical wavelengths in the transmission spectra of hot Jupiter atmospheres is sensitive to the bulk chemical properties of the atmosphere. To this end, we ran a grid of chemical models, which include TiO formation and destruction, for the ultra-hot Jupiter WASP-19b and an ultra-hot version of HD 209458b. We take into account non-equilibrium chemistry and changes in the temperature and pressure structure of these atmospheres caused by different C/O ratios. We calculated synthetic transmission spectra for these models, and studied the relative strengths of TiO and H2O features quantitatively. To compare with observations, we used a model-independent metric for molecular abundances, ΔZTiO−H2O/Heq, which has previously been used in observational studies of exoplanetary atmospheres. We find that with this metric we can differentiate between different chemical models and place constraints on the bulk carbon and oxygen abundances of the atmosphere. From chemical considerations, we expected the TiO abundance to depend on the bulk nitrogen. However, we find that changes in N/H do not result in changes in the resulting TiO. We applied our method to a set of known exoplanets that have been observed in the relevant optical wavelengths and find good agreement between low-resolution observations and our model for WASP-121b, marginally good agreement with WASP-79b, WASP-76b, and WASP-19b, and poorer agreement with HD 209458b. Our method will be particularly helpful for indirect studies of the bulk abundances of carbon and oxygen.

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HST/STIS transmission spectrum of the ultra-hot Jupiter WASP-76 b confirms the presence of sodium in its atmosphere

Cited by 34 publications

References 74 publications

ESPRESSO high-resolution transmission spectroscopy of WASP-76 b

ESPRESSO high-resolution transmission spectroscopy of WASP-76 b

Terminus: A Versatile Simulator for Space-based Telescopes

Tracing bulk elemental ratios in exoplanetary atmospheres with TiO chemistry

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