High-resolution Transit Spectroscopy of Warm Saturns

Deibert, Emily; Mooij, Ernst de; Jayawardhana, Ray; Fortney, Jonathan J.; Brogi, Matteo; Rustamkulov, Zafar; Tamura, Motohide

doi:10.3847/1538-3881/aaf56b

Cited by 35 publications

(41 citation statements)

References 52 publications

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“…Although the LBT results indicate a nondetection of potassium, we cannot confidentially rule out the existence of a weak K feature, considering the large errors of the light curves acquired with narrow spectral bins and the effect of telluric oxygen absorption adjacent to the K absorption lines. Deibert et al (2019) observed the transit of HAT-P-12b with the echelle high-dispersion spectrograph mounted on the Subaru telescope. These authors achieved a 3.2 σ detection of sodium absorption.…”

Section: Comparison With Hst Results In the Visiblementioning

confidence: 99%

“…Sing et al (2016) obtained the optical transmission spectrum of the planet using the Space Telescope Imaging Spectrograph (STIS) mounted on HST and discovered a Rayleigh-scattering feature as well as indications for K absorption. Deibert et al (2019) reported a tentative detection of Na with the high-dispersion spectrograph mounted on the Subaru telescope, but they were not able to detect the K feature. Alexoudi et al (2018 reanalyzed the optical HST data to investigate a discrepancy of the S2016 result compared to a previously published ground-based broadband transmission spectrum of HAT-P-12b, which did not show a slope (Mallonn et al 2015).…”

Section: Introductionmentioning

confidence: 99%

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LBT transmission spectroscopy of HAT-P-12b

Yan

Espinoza

Molaverdikhani

et al. 2020

A&A

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The hot sub-Saturn-mass exoplanet HAT-P-12b is an ideal target for transmission spectroscopy because of its inflated radius. We observed one transit of the planet with the multi-object double spectrograph (MODS) on the Large Binocular Telescope (LBT) with the binocular mode and obtained an atmosphere transmission spectrum with a wavelength coverage of ~0.4–0.9 μm. The spectrum is relatively flat and does not show any significant sodium or potassium absorption features. Our result is consistent with the revised Hubble Space Telescope (HST) transmission spectrum of a previous work, except that the HST result indicates a tentative detection of potassium. The potassium discrepancy could be the result of statistical fluctuation of the HST dataset. We fit the planetary transmission spectrum with an extensive grid of cloudy models and confirm the presence of high-altitude clouds in the planetary atmosphere. The fit was performed on the combined LBT and HST spectrum, which has an overall wavelength range of 0.4–1.6 μm. The LBT/MODS spectrograph has unique advantages in transmission spectroscopy observations because it can cover a wide wavelength range with a single exposure and acquire two sets of independent spectra simultaneously.

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Section: Comparison With Hst Results In the Visiblementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

LBT transmission spectroscopy of HAT-P-12b

Yan

Espinoza

Molaverdikhani

et al. 2020

A&A

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“…We then calculated the 1σ and 3σ detection limits using the phaseshuffling method (e.g. Esteves et al 2017;Deibert et al 2019). This is done by assigning random in-transit phases to the total CCF during the transit then integrating them at the planetary rest frame by adopting the K p of the detected signal.…”

Section: Non-detection Of Other Thermal Inversion Agentsmentioning

confidence: 99%

Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

Nugroho

Gibson

Mooij

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We analyse the transmission spectra of KELT-20b/MASCARA-2b to search for possible thermal inversion agents. The data consist of three transits obtained using HARPSN and one using CARMENES. We removed stellar and telluric lines before cross-correlating the residuals with spectroscopic templates produced using a 1D plane-parallel model, assuming an isothermal atmosphere and chemical equilibrium at solar metallicity. Using a likelihood-mapping method, we detect Fe i at > 13σ, Ca ii H$\&$K at > 6σ and confirm the previous detections of Fe ii, Ca ii IR Triplet, and Na i D. The detected signal of Fe i is shifted by −3.4 ± 0.4 km s−1 from the planetary rest frame, which indicates a strong day–night wind. Our likelihood-mapping technique also reveals that the absorption features of the detected species extend to different altitudes in the planet’s atmosphere. Assuming that the line lists are accurate, we do not detect other potential thermal inversion agents (NaH, MgH, AlO, SH, CaO, VO, FeH, and TiO) suggesting that non-chemical equilibrium mechanisms (e.g. a cold-trap) might have removed Ti- and V-bearing species from the upper atmosphere. Our results, therefore, show that KELT-20b/MASCARA-2b cannot possess an inversion layer caused by a TiO/VO-related mechanism. The presence of an inversion layer would therefore likely be caused by metal atoms such as Fe i and Fe ii. Finally, we report a double-peak structure in the Fe i signal in all of our data sets that could be a signature of atmospheric dynamics. However, further investigation is needed to robustly determine the origin of the signal.

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“…Using WFC3 on the HST, the planet was found to have a muted water feature at 1.4 µm with an overlying slope of a larger planet radius toward bluer wavelengths (Tsiaras et al 2018). Furthermore, absorption in Na D was detected during transit using high-resolution observations obtained with the HARPS spectrograph (Casasayas- Barris et al 2017), although an independent study using ESPaDOnS/CFHT could not confirm the sodium detection (Deibert et al 2019). This paper is organized as follows.…”

Section: Starmentioning

confidence: 99%

The GTC exoplanet transit spectroscopy survey

Murgas

Chen

Nortmann

et al. 2020

A&A

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Context. One of the main atmospheric features in exoplanet atmospheres, detectable both from ground- and space-based facilities, is Rayleigh scattering. In hydrogen-dominated planetary atmospheres, Rayleigh scattering causes the measured planetary radius to increase toward blue wavelengths in the optical range. Aims. We aim to detect and improve our understanding of several features in the optical range observable in planetary atmospheres. We focus on studying transiting exoplanets that present a wide range of orbital periods, masses, radii, and irradiation from their host star. Methods. We obtained a spectrophotometric time series of one transit of the Saturn-mass planet WASP-69b using the OSIRIS instrument at the Gran Telescopio Canarias. From the data we constructed 19 spectroscopic transit light curves representing 20 nm wide wavelength bins spanning from 515 to 905 nm. We derived the transit depth for each curve individually by fitting an analytical model together with a Gaussian process to account for systematic noise in the light curves. Results. We find that the transit depth increases toward bluer wavelengths, indicative of a larger effective planet radius. Our results are consistent with space-based measurements obtained in the near infrared using the Hubble Space Telescope, which show a compatible slope of the transmission spectrum. We discuss the origin of the detected slope and argue between two possible scenarios: a Rayleigh scattering detection originating in the planet’s atmosphere or a stellar activity induced signal from the host star.

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High-resolution Transit Spectroscopy of Warm Saturns

Cited by 35 publications

References 52 publications

LBT transmission spectroscopy of HAT-P-12b

LBT transmission spectroscopy of HAT-P-12b

Searching for thermal inversion agents in the transmission spectrum of KELT-20b/MASCARA-2b: detection of neutral iron and ionised calcium H&K lines

The GTC exoplanet transit spectroscopy survey

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