The atmosphere of WASP-17b: Optical high-resolution transmission spectroscopy

Khalafinejad, S.; Salz, M.; Cubillos, Patricio; Zhou, George; Essen, C. von; Husser, Tim-Oliver; Bayliss, Daniel; López‐Morales, Mercedes; Schmitt, J. H. M. M.; Lüftinger, T.

doi:10.1051/0004-6361/201732029

Cited by 18 publications

(20 citation statements)

References 64 publications

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“…Absorption excess in neutral Ca lines was firstly reported by Astudillo-Defru & Rojo (2013) in HD 209458b atmosphere, and the Ca + triplet lines variation during a transit was studied for the first time by Khalafinejad et al (2018) as indicator of stellar activity. Hoeijmakers et al (2018) detected Fe, Fe + , and Ti + atoms in the KELT-9b atmosphere, using the cross-correlation technique.…”

Section: Discussionmentioning

confidence: 91%

Atmospheric characterization of the ultra-hot Jupiter MASCARA-2b/KELT-20b

Casasayas-Barris

Πάλλη

Yan

et al. 2019

A&A

139

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Ultra-hot Jupiters orbit very close to their host star and consequently receive strong irradiation, causing their atmospheric chemistry to be different from the common gas giants. Here, we have studied the atmosphere of one of these particular hot planets, MASCARA-2b/KELT-20b, using four transit observations with high resolution spectroscopy facilities. Three of these observations were performed with HARPS-N and one with CARMENES. Additionally, we simultaneously observed one of the transits with MuSCAT2 to monitor possible spots in the stellar surface. At high resolution, the transmission residuals show the effects of Rossiter-McLaughlin and centre-to-limb variations from the stellar lines profiles, which we have corrected to finally extract the transmission spectra of the planet. We clearly observe the absorption features of CaII, FeII, NaI, Hα, and Hβ in the atmosphere of MASCARA-2b, and indications of Hγ and MgI at low signal-to-noise ratio. In the case of NaI, the true absorption is difficult to disentangle from the strong telluric and interstellar contamination. The results obtained with CARMENES and HARPS-N are consistent, measuring an Hα absorption depth of 0.68 ± 0.05 and 0.59 ± 0.07%, and NaI absorption of 0.11 ± 0.04 and 0.09 ± 0.05% for a 0.75 Å passband, in the two instruments respectively. The Hα absorption corresponds to ~1.2 Rp, which implies an expanded atmosphere, as a result of the gas heating caused by the irradiation received from the host star. For Hβ and Hγ only HARPS-N covers this wavelength range, measuring an absorption depth of 0.28 ± 0.06 and 0.21 ± 0.07%, respectively. For CaII, only CARMENES covers this wavelength range measuring an absorption depth of 0.28 ± 0.05, 0.41 ± 0.05 and 0.27 ± 0.06% for CaII λ8498Å, λ8542Å and λ8662Å lines, respectively. Three additional absorption lines of FeII are observed in the transmission spectrum by HARPS-N (partially covered by CARMENES), measuring an average absorption depth of 0.08 ± 0.04% (0.75 Å passband). The results presented here are consistent with theoretical models of ultra-hot Jupiters atmospheres, suggesting the emergence of an ionised gas on the day-side of such planets. Calcium and iron, together with other elements, are expected to be singly ionised at these temperatures and be more numerous than its neutral state. The Calcium triplet lines are detected here for the first time in transmission in an exoplanet atmosphere.

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Section: Discussionmentioning

confidence: 91%

Atmospheric characterization of the ultra-hot Jupiter MASCARA-2b/KELT-20b

Casasayas-Barris

Πάλλη

Yan

et al. 2019

A&A

139

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“…For hot Jupiters, a plethora of sodium detections have been confirmed, starting with Charbonneau et al (2002) in low resolution and Snellen et al (2008); Redfield et al (2008) up to more recent high resolution observations (e. g. Louden & Wheatley (2015); Ridden-Harper et al (2016); Wyttenbach et al (2015Wyttenbach et al ( , 2017; Casasayas- Barris et al (2017); Jensen et al (2018); Khalafinejad et al (2018); Seidel et al (2019)).…”

Section: Introductionmentioning

confidence: 92%

Wind of change: retrieving exoplanet atmospheric winds from high-resolution spectroscopy

Seidel

Ehrenreich

Pino

et al. 2020

A&A

124

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Context. The atmosphere of exoplanets has been studied extensively in recent years, using numerical models to retrieve chemical composition, dynamical circulation or temperature from data. One of the best observational probes in transmission is the sodium doublet, due to its large cross section. However, modelling the shape of the planetary sodium lines has proven to be challenging. Models with different assumptions regarding the atmosphere have been employed to fit the lines in the literature, yet statistically sound direct comparisons of different models are needed to paint a clear picture. Aims. We will compare different wind and temperature patterns and provide a tool to distinguish them driven by their best fit for the sodium transmission spectrum of the hot Jupiter HD 189733b. We parametrise different possible wind patterns already tested in literature and introduce the new option of an upwards driven vertical wind. Methods. We construct a forward model where the wind speed, wind geometry and temperature are injected into the calculation of the transmission spectrum. We embed this forward model in a nested sampling retrieval code to rank the models via their Bayesian evidence.Results. We retrieve a best-fit to the HD 189733b data for vertical upward winds |v ver (mean)| = 40 ± 4 km s −1 at altitudes above 10 −6 bar. With the current data from HARPS, we cannot distinguish wind patterns for higher pressure atmospheric layers. Conclusions. We show that vertical upwards winds in the upper atmosphere are a possible explanation for the broad sodium signature in hot Jupiters. We highlight other influences on the width of the doublet and explore strong magnetic fields acting on the lower atmosphere as one possible origin of the retrieved wind speed.

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“…In this section, we use the term "light curve" to refer to the timeseries of the line cores (line indices). For this purpose, we first look for the center of each line by fitting a Gaussian, integrating the flux in a 1.5 Å pass-band centered on the core of the line, and dividing it by the integrated flux of the reference band in the continuum (Khalafinejad et al 2018). In principle, a Lorenzian profile can better explain the line shape compared to a Gaussian profile; however, due to the relatively large scatter of the data here, neither one has an advantage over the other.…”

Section: Stellar Activity and Excess Light Curvesmentioning

confidence: 99%

Probing the atmosphere of WASP-69 b with low- and high-resolution transmission spectroscopy

Khalafinejad,

Molaverdikhani,

Blecic

et al. 2021

Preprint

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Consideration of both low-and high-resolution transmission spectroscopy is key for obtaining a comprehensive picture of exoplanet atmospheres. In studies of transmission spectra, the continuum information is well established with low-resolution spectra, while the shapes of individual lines are best constrained with high-resolution observations. In this work, we aim to merge high-with lowresolution transmission spectroscopy to place tighter constraints on physical parameters of the atmospheres. We present the analysis of three primary transits of WASP-69 b in the visible (VIS) channel of the CARMENES instrument and perform a combined lowand high-resolution analysis using additional data from HARPS-N, OSIRIS/GTC, and WFC3/HST already available in the literature. We investigate the Na i D 1 and D 2 doublet, Hα, the Ca ii infra-red triplet (IRT), and K i λ7699 Å lines, and we monitor the stellar photometric variability by performing long-term photometric observations with the STELLA telescope. During the first CARMENES observing night, we detected the planet Na i D 2 and D 1 lines at ∼ 7σ and ∼ 3σ significance levels, respectively. We measured a D 2 /D 1 intensity ratio of 2.5±0.7, which is in agreement with previous HARPS-N observations. Our modelling of WFC3 and OSIRIS data suggests strong Rayleigh scattering, solar to super-solar water abundance, and a highly muted Na feature in the atmosphere of this planet, in agreement with previous investigations of this target. We use the continuum information retrieved from the low-resolution spectroscopy as a prior to break the degeneracy between the Na abundance, reference pressure, and thermosphere temperature for the high-resolution spectroscopic analysis. We fit the Na i D 1 and D 2 lines individually and find that the posterior distributions of the model parameters agree with each other within 1σ. Our results suggest that local thermodynamic equilibrium processes can explain the observed D 2 /D 1 ratio because the presence of haze opacity mutes the absorption features.

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The atmosphere of WASP-17b: Optical high-resolution transmission spectroscopy

Cited by 18 publications

References 64 publications

Atmospheric characterization of the ultra-hot Jupiter MASCARA-2b/KELT-20b

Atmospheric characterization of the ultra-hot Jupiter MASCARA-2b/KELT-20b

Wind of change: retrieving exoplanet atmospheric winds from high-resolution spectroscopy

Probing the atmosphere of WASP-69 b with low- and high-resolution transmission spectroscopy

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