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

Luque, R.; Casasayas-Barris, N.; Parviainen, H.; Chen, G.; Πάλλη, Ε.; Livingston, John H.; Béjar, V. J. S.; Crouzet, Nicolas; Esparza-Borges, E.; Fukui, A.; Hidalgo, D.; Kawashima, Yui; Kawauchi, Kiyoe; Klagyivik, P.; Kurita, S.; Kusakabe, Nobuhiko; Leon, Jerome P. de; Madrigal-Aguado, A.; Montañés-Rodŕıguez, P.; Mori, Mayuko; Murgas, F.; Narita, Norio; Nishiumi, Taku; Nowak, G.; Oshagh, M.; Sánchez-Benavente, Manuel; Stangret, M.; Tamura, Motohide; Terada, Yuka; Watanabe, Noriharu

doi:10.1051/0004-6361/202038703

Cited by 17 publications

(23 citation statements)

References 80 publications

(92 reference statements)

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“…Other studies have applied, or fitted for, offsets without wavelength overlap. In a study of WASP-74 b with photometry from ground-based instruments along with HST/WFC3 and Spitzer/IRAC, Luque et al (2020) fitted for an offset for the HST data, discovering a best-fit value of 434 or 615 ppm, depending upon the additional data used. Wilson et al (2020) obtained FORS2 data of WASP-103 b and combined it with other ground-based data as well as data from HST and Spitzer.…”

Section: Offset Between Hst and Vlt Observationsmentioning

confidence: 99%

On the Compatibility of Ground-based and Space-based Data: WASP-96 b, an Example*

Yip

Changeat

Edwards

et al. 2020

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The study of exoplanetary atmospheres relies on detecting minute changes in the transit depth at different wavelengths. To date, a number of ground-and space-based instruments have been used to obtain transmission spectra of exoplanets in different spectral bands. One common practice is to combine observations from different instruments in order to achieve a broader wavelength coverage. We present here two inconsistent observations of WASP-96 b, one by the Hubble Space Telescope (HST) and the other by the Very Large Telescope (VLT). We present two key findings in our investigation: (1) a strong water signature is detected via the HST WFC3 observations and (2) a notable offset in transit depth (>1100 ppm) can be seen when the ground-based and space-based observations are combined. The discrepancy raises the question of whether observations from different instruments could indeed be combined. We attempt to align the observations by including an additional parameter in our retrieval studies but are unable to definitively ascertain that the aligned observations are indeed compatible. The case of WASP-96 b signals that compatibility of instruments should not be assumed. While wavelength overlaps between instruments can help, it should be noted that combining data sets remains risky business. The difficulty of combining observations also strengthens the need for next-generation instruments that possess broader spectral coverage.

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Section: Offset Between Hst and Vlt Observationsmentioning

confidence: 99%

On the Compatibility of Ground-based and Space-based Data: WASP-96 b, an Example*

Yip

Changeat

Edwards

et al. 2020

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“…Super-Rayleigh slopes have been observed in several exoplanet atmospheres before (e.g. HD189733 b, WASP-127 b, WASP-21 b, WASP-74 b, WASP-104 b; Sing et al 2011;Palle et al 2017;Alderson et al 2020;Luque et al 2020;Chen et al 2021). Several explanations have been suggested for this, including based on additional opacity sources such as mineral clouds (e.g.…”

Section: Scattering Slopementioning

confidence: 94%

LRG-BEASTS: sodium absorption and Rayleigh scattering in the atmosphere of WASP-94A b using NTT/EFOSC2

Ahrer,

Wheatley,

Kirk

et al. 2022

Preprint

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We present an optical transmission spectrum for WASP-94A b, the first atmospheric characterisation of this highly-inflated hot Jupiter. The planet has a reported radius of 1.72 +0.06 −0.05 R Jup , a mass of only 0.456 +0.032 −0.036 M Jup , and an equilibrium temperature of 1508 ± 75 K. We observed the planet transit spectroscopically with the EFOSC2 instrument on the ESO New Technology Telescope (NTT) at La Silla, Chile: the first use of NTT/EFOSC2 for transmission spectroscopy. We achieved an average transitdepth precision of 128 ppm for bin widths of ∼ 200 Å. This high precision was achieved in part by linking Gaussian Process hyperparameters across all wavelength bins. The resulting transmission spectrum, spanning a wavelength range of 3800−7140 Å, exhibits a sodium absorption with a significance of 4.9𝜎, suggesting a relatively cloud-free atmosphere. The sodium signal may be broadened, with a best fitting width of 78 +67 −32 Å in contrast to the instrumental resolution of 27.2 ± 0.2 Å. We also detect a steep slope in the blue end of the transmission spectrum, indicating the presence of Rayleigh scattering in the atmosphere of WASP-94A b. Retrieval models show evidence for the observed slope to be super-Rayleigh and potential causes are discussed. Finally, we find narrow absorption cores in the CaII H&K lines of WASP-94A, suggesting the star is enshrouded in gas escaping the hot Jupiter.

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“…The Spitzer/InfraRed Array Camera (IRAC) broadband photometry at 3.6, 4.5, 5.8, and 8.0 µm has suggested the possible presence of carbon molecules (Beaulieu et al 2011;Knutson et al 2011;Morello et al 2015). Combined spectra from different space-and/or ground-based instruments covering UV to infrared wavelengths have also been analyzed in the literature (Danielski et al 2014;Sing et al 2016;Barstow et al 2017;Mancini et al 2019;Pinhas et al 2019;Luque et al 2020).…”

Section: Havementioning

confidence: 99%

Phase-curve Pollution of Exoplanet Transmission Spectra

Morello

Zingalès

Martin-Lagarde

et al. 2021

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The occurrence of a planet transiting in front of its host star offers the opportunity to observe the planet's atmosphere filtering starlight. The fraction of occulted stellar flux is roughly proportional to the optically thick area of the planet, the extent of which depends on the opacity of the planet's gaseous envelope at the observed wavelengths. Chemical species, haze, and clouds are now routinely detected in exoplanet atmospheres through rather small features in transmission spectra, i.e., collections of planet-to-star area ratios across multiple spectral bins and/or photometric bands. Technological advances have led to a shrinking of the error bars down to a few tens of parts per million (ppm) per spectral point for the brightest targets. The upcoming James Webb Space Telescope (JWST) is anticipated to deliver transmission spectra with precision down to 10 ppm. The increasing precision of measurements requires a reassessment of the approximations hitherto adopted in astrophysical models, including transit light curve models. Recently, it has been shown that neglecting the planet's thermal emission can introduce significant biases in the transit depth measured with the JWST/Mid-InfraRed Instrument, integrated between 5 and 12 µm. In this paper, we take a step forward by analyzing the effects of the approximation on transmission spectra over the 0.6-12 µm wavelength range covered by various JWST instruments. We present open source software to predict the spectral bias, showing that, if not corrected, it may affect the inferred molecular abundances and thermal structure of some exoplanet atmospheres.

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

Cited by 17 publications

References 80 publications

On the Compatibility of Ground-based and Space-based Data: WASP-96 b, an Example*

On the Compatibility of Ground-based and Space-based Data: WASP-96 b, an Example*

LRG-BEASTS: sodium absorption and Rayleigh scattering in the atmosphere of WASP-94A b using NTT/EFOSC2

Phase-curve Pollution of Exoplanet Transmission Spectra

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