Atmospheric Transmission Spectroscopy of Hot Jupiter KELT-10b using Synthetic Telluric Correction Software

McCloat, Sean; Essen, C. von; Fieber-Beyer, S. K.

doi:10.3847/1538-3881/ac132b

Cited by 4 publications

(11 citation statements)

References 44 publications

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“…This hot Jupiter has many properties similar to the benchmark planet system HD 209458 b, providing a valuable opportunity to compare these two planets. It notably features a sodium detection obtained by McCloat et al (2021) with VLT/UVES. We obtained two transits with HARPS as part of HEARTS, which is further discussed in Sect.…”

Section: Radius [R ]mentioning

confidence: 80%

“…If the observed UVES signal is truly redshifted, we could explain the "emission-like" shoulders apparent in the UVES transmission spectrum (Fig. 4 in McCloat et al 2021). However, only the D1 signal there seems to be as broad as our simulation, while the D2 signal appears to be due to a few pixels.…”

Section: Correction For Stellar Effectsmentioning

confidence: 99%

“…However, doing so disregards the RM and center-to-limb variation (CLV) effects that can affect our spectra. This approach is the one McCloat et al (2021) took, as the lack of precise wavelength calibration in their UVES data disallowed the measurement of RVs from the spectra, preventing an RM correction. HARPS, however, is designated to provide accurate RVs, hence we could measure and correct for the RM effect and simulate its impact on the final transmission spectrum.…”

Section: Correction For Stellar Effectsmentioning

confidence: 99%

“…Figure 7 shows the comparison between our EVE simulation and the best-fit model to the UVES transmission spectrum from 6 https://github.com/bertrandplez/Turbospectrum2019 McCloat et al (2021) in the region of the sodium doublet. We are unable to explain the observed signal with the pure RM and CLV effects.…”

Section: Correction For Stellar Effectsmentioning

confidence: 99%

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Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Attia

Ehrenreich

et al. 2023

A&A

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Context. The HEARTS survey aims to probe the upper layers of the atmosphere by detecting resolved sodium doublet lines, a tracer of the temperature gradient, and atmospheric winds. KELT-10b, one of the targets of HEARTS, is a hot-inflated Jupiter with 1.4 RJup and 0.7 MJup. Recently, there was a report of sodium absorption in the atmosphere of KELT-10b (0.66% ± 0.09% (D2) and 0.43% ± 0.09% (D1)); VLT/UVES data from single transit). Aims. We searched for potential atmospheric species in KELT-10b, focusing on sodium doublet lines (Na I; 589 nm) and the Balmer alpha line (Hα; 656 nm) in the transmission spectrum. Furthermore, we measured the planet-orbital alignment with the spin of its host star. Methods. We used the Rossiter-McLaughlin Revolutions technique to analyze the local stellar lines occulted by the planet during its transit. We used the standard transmission spectroscopy method to probe the planetary atmosphere, including the correction for telluric lines and the Rossiter-McLaughlin effect on the spectra. We analyzed two new light curves jointly with the public photometry observations. Results. We do not detect signals in the Na I and H α lines within the uncertainty of our measurements. We derive the 3σ upper limit of excess absorption due to the planetary atmosphere corresponding to equivalent height Rp to 1.8Rp (Na I) and 1.9Rp (H α). The analysis of the Rossiter-McLaughlin effect yields the sky-projected spin-orbit angle of the system λ = −5.2 ± 3.4° and the stellar projected equatorial velocity υeqsin i⋆ = 2.58 ± 0.12 km s−1. Photometry results are compatible within 1σ with previous studies. Conclusions. We found no evidence of Na I and H α, within the precision of our data, in the atmosphere of KELT-10b. Our detection limits allow us to rule out the presence of neutral sodium or excited hydrogen in an escaping extended atmosphere around KELT-10b. We cannot confirm the previous detection of Na I at lower altitudes with VLT/UVES. We note, however, that the Rossiter-McLaughlin effect impacts the transmission spectrum on a smaller scale than the previous detection with UVES. Analysis of the planet-occulted stellar lines shows the sky-projected alignment of the system, which is likely truly aligned due to tidal interactions of the planet with its cool (Teff < 6250 K) host star.

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Section: Radius [R ]mentioning

confidence: 80%

Section: Correction For Stellar Effectsmentioning

confidence: 99%

Section: Correction For Stellar Effectsmentioning

confidence: 99%

Section: Correction For Stellar Effectsmentioning

confidence: 99%

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Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Attia

Ehrenreich

et al. 2023

A&A

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“…However, this has in turn biased detections of sodium absorption from the ground to exoplanets with short transit durations. (less than five hours, such as Borsa et al (2021) on WASP-121b;McCloat et al (2021) on KELT-10;or Allart et al (2020) on WASP-127b). KELT-11 b transits in front of its host star for 7.1 hours.…”

Section: -Day Observation Methodsmentioning

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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Optimising spectroscopic observations of transiting exoplanets

Boldt-Christmas,

Lesjak,

Wehrhahn

et al. 2024

A&A

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When observing the atmospheres of transiting exoplanets using high-resolution spectroscopy, the aim is to detect well-resolved spectral features with high signal-to-noise ratios (S/Ns), as is possible today with modern spectrographs. However, obtaining such high-quality observations comes with a trade-off: a lower cadence of fewer, longer exposures across the transit collects more photons thanks to reduced overheads, enhancing the S/N of each observation, while a higher cadence of several shorter exposures minimises spectral feature smearing due to the continuously changing radial velocity of the planet. Considering that maximising S/N and minimising smearing are both beneficial to analysis, there is a need to identify the optimal compromise between the two for a given target. In this work, we aim to establish where this compromise lies for a typical exoplanet transit observation in order to benefit future data collection and subsequent interpretation. We modelled real transit events based on targets as they would be observed with VLT/ at Paranal Observatory, Chile. Creating four hypothetical scenarios, we simulated each set of transmission spectra across 100 realisations of the same transit event in order to vary the time resolution only. We removed telluric and stellar lines from these data sets using the algorithm and analysed them through cross-correlation with model templates, measuring how successfully each time resolution and case detected the planetary signal and exploring how the results vary. We demonstrate that there is a continuous change in the significance of the cross-correlation detection based on the trade-off between high and low time resolutions, and that, averaged over a large number of realisations, the function of this significance has clear maxima. The strength and location of these maxima vary depending on, for example, planet system parameters, instrumentation, and the number of removal iterations. We discuss why observers should therefore take several factors into account using a strategy akin to the `exposure triangle' employed in traditional photography where a balance must be struck by considering the full context of the observation. Our method is robust and may be employed by observers to estimate the best observational strategies for other targets.

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Atmospheric Transmission Spectroscopy of Hot Jupiter KELT-10b using Synthetic Telluric Correction Software

Cited by 4 publications

References 44 publications

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Optimising spectroscopic observations of transiting exoplanets

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