A GROUND-BASED OPTICAL TRANSMISSION SPECTRUM OF WASP-6b

Jordán, Andrés; Espinoza, N.; Rabus, M.; Eyheramendy, S.; Sing, David K.; Désert, Jean-Michel; Bakos, G. Á.; Fortney, Jonathan J.; López‐Morales, Mercedes; Maxted, P. F. L.; Triaud, A. H. M. J.; Szentgyorgyi, Andrew

doi:10.1088/0004-637x/778/2/184

Cited by 112 publications

(116 citation statements)

References 58 publications

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“…We caution that differences can occur due to different telescope size, target brightness, and the complexity of systematics in the light curves and analysis techniques. However, our average uncertainty of k 2 for the 200 Å channels of 3.6 × 10 −4 agrees well with the range of literature values 1.8-3.4 × 10 −4 (Gibson et al 2013a,b;Jordán et al 2013;Murgas et al 2014). One reason for our uncertainty to be slightly larger is certainly the lack of an out-of-transit baseline on one side.…”

Section: Transmission Spectrumsupporting

confidence: 90%

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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Section: Transmission Spectrumsupporting

confidence: 90%

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

Mallonn

Essen

Weingrill

et al. 2015

A&A

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“…Following the framework detailed by Jordán et al (2013), we modeled the observed target light curve l t ( ) as…”

Section: Pca-based Modeling Frameworkmentioning

confidence: 99%

ACCESS I. AN OPTICAL TRANSMISSION SPECTRUM OF GJ 1214b REVEALS A HETEROGENEOUS STELLAR PHOTOSPHERE

Rackham

Espinoza

Apai

et al. 2017

ApJ

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GJ1214b is the most studied sub-Neptune exoplanet to date. Recent measurements have shown its near-infrared transmission spectrum to be flat, pointing to a high-altitude opacity source in the exoplanetʼs atmosphere, either equilibrium condensate clouds or photochemical hazes. Many photometric observations have been reported in the optical by different groups, though simultaneous measurements spanning the entire optical regime are lacking. We present an optical transmission spectrum (4500-9260Å) of GJ1214b in 14 bins, measured with Magellan/IMACS repeatedly over three transits. We measure a mean planet-to-star radius ratio of ( ) in the spectral bins. The optical transit depths are shallower on average than observed in the near-infrared. We present a model for jointly incorporating the effects of a composite photosphere and atmospheric transmission through the exoplanetʼs limb (the CPAT model), and use it to examine the cases of absorber and temperature heterogeneities in the stellar photosphere. We find the optical and near-infrared measurements are best explained by the combination of (1) photochemical haze in the exoplanetary atmosphere with a mode particle size r=0.1μm and haze-forming efficiency = f 10% haze and (2) faculae in the unocculted stellar disk with a temperature contrast D = -+ T 354 46 46 K, assuming 3.2% surface coverage. The CPAT model can be used to assess potential contributions of heterogeneous stellar photospheres to observations of exoplanet transmission spectra, which will be important for searches for spectral features in the optical.

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“…While we do not detect any atmospheric features on HATS-5b, the large scale height makes HATS-5b an appealing target for future transmission spectroscopy observations. Future observations in the bluer U band may also reveal opacity variations in the atmosphere by H 2 Rayleigh scattering (e.g., Sing et al 2011Sing et al , 2013Jordán et al 2013;Nascimbeni et al 2013). …”

Section: Notesmentioning

confidence: 99%

HATS-5b: A TRANSITING HOT SATURN FROM THE HATSouth SURVEY

Zhou¹,

Bayliss²,

Penev³

et al. 2014

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We report the discovery of HATS-5b, a transiting hot Saturn orbiting a G-type star, by the HATSouth survey. HATS-5b has a mass of M p ≈ 0.24 M J , radius of R p ≈ 0.91 R J , and transits its host star with a period of P ≈ 4.7634 days. The radius of HATS-5b is consistent with both theoretical and empirical models. The host star has a V-band magnitude of 12.6, mass of 0.94 M , and radius of 0.87 R . The relatively high scale height of HATS-5b and the bright, photometrically quiet host star make this planet a favorable target for future transmission spectroscopy follow-up observations. We reexamine the correlations in radius, equilibrium temperature, and metallicity of the close-in gas giants and find hot Jupiter-mass planets to exhibit the strongest dependence between radius and equilibrium temperature. We find no significant dependence in radius and metallicity for the close-in gas giant population.

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A GROUND-BASED OPTICAL TRANSMISSION SPECTRUM OF WASP-6b

Cited by 112 publications

References 58 publications

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

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

ACCESS I. AN OPTICAL TRANSMISSION SPECTRUM OF GJ 1214b REVEALS A HETEROGENEOUS STELLAR PHOTOSPHERE

HATS-5b: A TRANSITING HOT SATURN FROM THE HATSouth SURVEY

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