HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering

Sing, David K.; Wakeford, Hannah R.; Showman, Adam P.; Nikolov, Nikolay; Fortney, Jonathan J.; Burrows, Adam; Ballester, G. E.; Deming, Drake; Aigrain, S.; Désert, Jean-Michel; Gibson, Neale P.; Henry, Gregory W.; Knutson, Heather A.; Étangs, A. Lecavelier des; Pont, F.; Vidal‐Madjar, A.; Williamson, Michael; Wilson, Paul

doi:10.1093/mnras/stu2279

Cited by 201 publications

(271 citation statements)

References 70 publications

(124 reference statements)

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“…signals which affected all curves in an identical manner. Such common-mode corrections are usual practice when dealing with spectrophotometric transit data (Gibson et al 2013b;Sing et al 2015). In accordance with expectation the correction appears to fully dispose of the light curve distortion we suspect to be caused by the wavelength-independent pupil vignetting (see Sect.…”

Section: Analysis Of the Color Light Curves Of Runsupporting

confidence: 83%

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The GTC exoplanet transit spectroscopy survey

Nortmann

Pallé

Murgas

et al. 2016

A&A

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We observed the hot Jupiter HAT-P-32b (also known as HAT-P-32Ab) to determine its optical transmission spectrum by measuring the wavelength-dependent planet-to-star radius ratios in the region between 518 -918 nm. We used the OSIRIS instrument at the GTC in long slit spectroscopy mode, placing HAT-P-32 and a reference star in the same slit and obtaining a time series of spectra covering two transit events. Using the best quality data set, we were able to yield 20 narrow-band transit light curves, with each passband spanning a 20 nm wide interval. After removal of all systematic noise signals and light curve modeling the uncertainties for the resulting radius ratios lie between 337 and 972 ppm. The radius ratios show little variation with wavelength suggesting a high altitude cloud layer masking any atmospheric features. Alternatively, a strong depletion in alkali metals or a much smaller than expected planetary atmospheric scale height could be responsible for the lack of atmospheric features. Our result of a flat transmission spectrum is consistent with a previous ground-based study of the optical spectrum of this planet. This agreement between independent results demonstrates that ground-based measurements of exoplanet atmospheres can give reliable and reproducible results despite the fact that the data often is heavily affected by systematic noise, as long as the noise source is well understood and properly corrected. We also extract an optical spectrum of the M-dwarf companion HAT-P-32B. Using PHOENIX stellar atmosphere models we determine an effective temperature of T eff = 3187 +60 −71 K, slightly colder than previous studies relying only on broadband infra-red data.

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Section: Analysis Of the Color Light Curves Of Runsupporting

confidence: 83%

“…Many successful measurements of wavelength-dependent planet radii have been obtained from space using the Hubble Space Telescope (HST) (e.g. Charbonneau et al 2002;Pont et al 2008;Berta et al 2012;Sing et al 2015). Moreover, in the last 4 years, ground-based observations have also yielded promising results (e.g.…”

Section: Introductionmentioning

confidence: 99%

The GTC exoplanet transit spectroscopy survey

Nortmann

Pallé

Murgas

et al. 2016

A&A

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“…For the symmetric transits, nine hot Jupiters (HAT-P-1b, HAT-P-12b, WASP43b, are observed to have a constant planetary radii from near-UV to optical wavelengths Turner et al 2013;Bento et al 2014;Nikolov et al 2014;Pearson, Turner & Sagan 2014;Mallonn et al 2015;Ricci et al 2015;Sing et al 2016). Additionally, 11 exoplanets with symmetric light curves (GJ 3470b, HD 189733b, HD 209458b, HAT-P-5b, HATP12b, WASP-6b, WASP-12b, WASP-17b, WASP-31b, WASP-39b, XO-2b) are observed to have a larger near-UV radii than optical wavelengths Sing et al 2008Sing et al , 2011Sing et al , 2013Sing et al , 2015Sing et al , 2016Southworth et al 2012b;Nascimbeni et al 2013;Zellem et al 2015). There seems to be a wavelength distinction between asymmetric and symmetric lights where asymmetric transits are only observed below 300 nm.…”

Section: Introductionmentioning

confidence: 98%

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

Turner

Pearson

Biddle

et al. 2016

Mon. Not. R. Astron. Soc.

101

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Transits of exoplanets observed in the near-UV have been used to study the scattering properties of their atmospheres and possible star-planet interactions. We observed the primary transits of 15 exoplanets (CoRoT-1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-16b, HAT-P-22b, TrES2b, in the near-UV and several optical photometric bands to update their planetary parameters, ephemerides, search for a wavelength dependence in their transit depths to constrain their atmospheres, and determine if asymmetries are visible in their light curves. Here, we present the first ground-based near-UV light curves for 12 of the targets (CoRoT1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-22b, TrES-2b, TrES-4b, WASP-1b, WASP-33b, WASP-36b, WASP-48b, and WASP-77Ab). We find that none of the near-UV transits exhibit any non-spherical asymmetries, this result is consistent with recent theoretical predictions by Ben-Jaffel et al. and Turner et al. The multiwavelength photometry indicates a constant transit depth from near-UV to optical wavelengths in 10 targets (suggestive of clouds), and a varying transit depth with wavelength in 5 targets (hinting at Rayleigh or aerosol scattering in their atmospheres). We also present the first detection of a smaller near-UV transit depth than that measured in the optical in WASP-1b and a possible opacity source that can cause such radius variations is currently unknown. WASP-36b also exhibits a smaller near-UV transit depth at

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“…Furthermore, it was ruled out for the somewhat cooler atmospheres of HAT-P-1b (Nikolov et al 2014). The non-detection of TiO in HD 189733b, HAT-P-32b, WASP-31b, and WASP-6b can be explained by clouds or haze on top of the atmosphere (Pont et al 2008;Gibson et al 2013b;Sing et al 2015;Nikolov et al 2015). …”

Section: Introductionmentioning

confidence: 99%

Transmission spectroscopy of the inflated exo-Saturn HAT-P-19b

Mallonn

Essen

Weingrill

et al. 2015

A&A

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Context. Transiting highly inflated giant planets offer the possibility of characterizing their atmospheres. A fraction of the starlight passes through the high-altitude layers of the planetary atmosphere during transit. The resulting absorption is expected to be wavelength dependent for cloud-free atmospheres with an amplitude of up to 10 −3 of the stellar flux, while a high-altitude cloud deck would cause a gray opacity. Aims. We observed the Saturn-mass and Jupiter-sized exoplanet HAT-P-19b to refine its transit parameters and ephemeris as well as to shed first light on its transmission spectrum. We monitored the host star over one year to quantify its flux variability and to correct the transmission spectrum for a slope caused by starspots. Methods. A transit of HAT-P-19b was observed spectroscopically with OSIRIS at the Gran Telescopio Canarias in January 2012. The spectra of the target and the comparison star covered the wavelength range from 5600 to 7600 Å. One high-precision differential light curve was created by integrating the entire spectral flux. This white-light curve was used to derive absolute transit parameters. Furthermore, a set of light curves over wavelength was formed by a flux integration in 41 wavelength channels of 50 Å width. We analyzed these spectral light curves for chromatic variations of transit depth. Results. The transit fit of the combined white-light curve yields a refined value of the planet-to-star radius ratio of 0.1390±0.0012 and an inclination of 88.89 ± 0.32 deg. After a re-analysis of published data, we refine the orbital period to 4.0087844 ± 0.0000015 days. We obtain a flat transmission spectrum without significant additional absorption at any wavelength or any slope. However, our accuracy is not sufficient to significantly rule out the presence of a pressure-broadened sodium feature. Our photometric monitoring campaign allowed for an estimate of the stellar rotation period of 35.5 ± 2.5 days and an improved age estimate of 5.5 +1.8 −1.3 Gyr by gyrochronology. The calculated correction of the transit depth for unocculted spots on the visible hemisphere was found to be well within the derived 1σ uncertainty of the white-light curve and the spectral data points of the transmission spectrum.

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HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering

Cited by 201 publications

References 70 publications

The GTC exoplanet transit spectroscopy survey

The GTC exoplanet transit spectroscopy survey

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

Transmission spectroscopy of the inflated exo-Saturn HAT-P-19b

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