The hot Neptune WASP-166 b with ESPRESSO II: confirmation of atmospheric sodium

Seidel, J. V.; Cegla, H. M.; Doyle, Lauren; Lafarga, M.; Brogi, Matteo; Gandhi, Siddharth; Anderson, D. R.; Allart, R.; Buchschacher, N.; Sоsnowska, Danuta

doi:10.1093/mnrasl/slac027

Cited by 15 publications

(16 citation statements)

References 35 publications

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“…WASP-166 has also been central to various other studies: Bryant et al ( 2020 ) use simultaneous photometric transit observations of WASP-166 b from TESS and NGTS and found the multiscope precision of NGTS can match TESS . Finally, Seidel et al ( 2020 ) use HARPS and then ESPRESSO (Seidel et al 2022 , same observations as in this paper) observations of WASP-166 b to detect neutral sodium in the planet atmosphere at a 3.4 σ level and tentati ve e vidence of line broadening. This suggests winds are responsible for pushing sodium further into space causing the bloated nature of this highly irradiated world.…”

mentioning

confidence: 99%

The Hot Neptune WASP-166 b with ESPRESSO – I. Refining the planetary architecture and stellar variability

Doyle

Cegla

Bryant

et al. 2022

Monthly Notices of the Royal Astronomical Society

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In this paper, we present high-resolution spectroscopic transit observations from ESPRESSO of the super-Neptune WASP-166 b. In addition to spectroscopic ESPRESSO data, we analyse photometric data from TESS of six WASP-166 b transits along with simultaneous NGTS observations of the ESPRESSO runs. These observations were used to fit for the planetary parameters as well as assessing the level of stellar activity (e.g. spot crossings, flares) present during the ESPRESSO observations. We utilize the Reloaded Rossiter McLaughlin (RRM) technique to spatially resolve the stellar surface, characterizing the centre-to-limb convection-induced variations, and to refine the star-planet obliquity. We find WASP-166 b has a projected obliquity of $\lambda = -15.52^{+2.85}_{-2.76}\, ^{\circ }$ and vsin (i) = 4.97 ± 0.09 kms−1 which is consistent with the literature. We were able to characterise centre-to-limb convective variations as a result of granulation on the surface of the star on the order of a few kms−1 for the first time. We modelled the centre-to-limb convective variations using a linear, quadratic and cubic model with the cubic being preferred. In addition, by modelling the differential rotation and centre-to-limb convective variations simultaneously we were able to retrieve a potential anti-solar differential rotational shear (α ∼ -0.5) and stellar inclination (i* either 42.03$^{+9.13}_{-9.60}\, ^{\circ }$ or 133.64$^{+8.42}_{-7.98}\, ^{\circ }$ if the star is pointing towards or away from us). Finally, we investigate how the shape of the cross-correlation functions change as a function of limb angle and compare our results to magnetohydrodynamic simulations.

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confidence: 99%

The Hot Neptune WASP-166 b with ESPRESSO – I. Refining the planetary architecture and stellar variability

Doyle

Cegla

Bryant

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…Their scale height is calculated using H = RT µg , assuming a hydrogen and helium atmosphere (µ = 2.4 g mol −1 ) and g = GM P R 2 P . Very few sodium signatures have been detected in and around the Neptune desert, most recently on WASP-166 b (Seidel et al 2022).…”

Section: Comparison With Previous Kelt-11 B Resultsmentioning

confidence: 99%

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Mounzer

Seidel

Attia

et al. 2022

A&A

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Context. High-resolution transmission spectroscopy has allowed for in-depth information on the composition and structure of exoplanetary atmospheres to be garnered in the last few years, especially in the visible and in the near-infrared. Many atomic and molecular species have been detected thanks to data gathered from state-of-the-art spectrographs installed on large ground-based telescopes. Nevertheless, the Earth daily cycle has been limiting observations to exoplanets with the shortest transits. Aims. The inflated sub-Saturn KELT-11 b has a hot atmosphere and orbits a bright evolved subgiant star, making it a prime choice for atmospheric characterization. The challenge lies in its transit duration -of more than seven hours -which can only be covered partially or without enough out-of-transit baselines when observed from the ground. Methods. To overcome this constraint, we observed KELT-11 b with the HARPS spectrograph in series of three consecutive nights, each focusing on a different phase of the planetary orbit: before, during, and after the transit. This allowed us to gather plenty of outof-transit baseline spectra, which was critical to build a spectrum of the unocculted star with sufficient precision. Telluric absorption lines were corrected using the atmospheric transmission code Molecfit. Individual high-resolution transmission spectra were merged to obtain a high signal-to-noise transmission spectrum to search for sodium in KELT-11 b's atmosphere through the ∼ 5900 Å doublet. Results. Our results highlight the potential for independent observations of a long-transiting planet over consecutive nights. Our study reveals a sodium excess absorption of 0.28 ± 0.05 % and 0.50 ± 0.06 % in the Na D1 and D2 lines, respectively. This corresponds to 1.44 and 1.69 times the white-light planet radius in the line cores. Wind pattern modeling tends to prefer day-to-night side winds with no vertical winds, which is surprising considering the planet bloatedness. The modeling of the Rossiter-Mclaughlin effect yields a significantly misaligned orbit, with a projected spin-orbit angle of λ = -77.86 +2.36 −2.26• . Conclusions. Belonging to the under-studied group of inflated sub-Saturns, the characteristics of KELT-11 b -notably its extreme scale height and long transit -make it an ideal and unique target for next-generation telescopes. Our results as well as recent findings from HST, TESS, and CHEOPS observations could make KELT-11 b a benchmark exoplanet in atmospheric characterization.

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“…Background WASP-166 b is a bloated, low-density super-Neptune on a close and aligned orbit around an F-star (Hellier et al 2019). Sodium was detected at high velocities and up to high altitudes in the planetary atmosphere, hinting at its hydrodynamical escape (Seidel et al 2020(Seidel et al , 2022.…”

Section: Wasp-166mentioning

confidence: 99%

Dream

Bourrier

Attia

Mallonn

et al. 2023

A&A

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The distribution of close-in exoplanets is shaped by a complex interplay between atmospheric and dynamical processes. The Desert-Rim Exoplanets Atmosphere and Migration (DREAM) program aims at disentangling those processes through the study of the hot Neptune desert, whose rim hosts planets that are undergoing, or survived, atmospheric evaporation and orbital migration. In this first paper, we use the Rossiter-McLaughlin revolutions (RMR) technique to investigate the orbital architecture of 14 close-in planets ranging from mini-Neptune to Jupiter-size and covering a broad range of orbital distances. While no signal is detected for the two smallest planets, we were able to constrain the sky-projected spin-orbit angle of six planets for the first time, to revise its value for six others, and, thanks to constraints on the stellar inclination, to derive the 3D orbital architecture in seven systems. These results reveal a striking three-quarters of polar orbits in our sample, all being systems with a single close-in planet but of various stellar and planetary types. High-eccentricity migration is favored to explain such orbits for several evaporating warm Neptunes, supporting the role of late migration in shaping the desert and populating its rim. Putting our measurements in the wider context of the close-in planet population will be useful to investigate the various processes shaping their architectures.

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The hot Neptune WASP-166 b with ESPRESSO II: confirmation of atmospheric sodium

Cited by 15 publications

References 35 publications

The Hot Neptune WASP-166 b with ESPRESSO – I. Refining the planetary architecture and stellar variability

The Hot Neptune WASP-166 b with ESPRESSO – I. Refining the planetary architecture and stellar variability

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

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