THE FLAT TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ1214b FROM WIDE FIELD CAMERA 3 ON THE<i>HUBBLE SPACE TELESCOPE</i>

Berta, Zachory K.; Charbonneau, David; Désert, Jean-Michel; Kempton, Eliza M.-R.; McCullough, P. R.; Burke, Christopher J.; Fortney, Jonathan J.; Irwin, Jonathan; Nutzman, P.; Homeier, D.

doi:10.1088/0004-637x/747/1/35

Cited by 361 publications

(518 citation statements)

References 85 publications

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“…Since its discovery, many groups have published measurements of GJ1214bʼs transmission spectrum in the optical and nearinfrared (Bean et al 2010Croll et al 2011;Crossfield et al 2011;Désert et al 2011;Berta et al 2012;de Mooij et al 2012de Mooij et al , 2013Murgas et al 2012;Colón & Gaidos 2013;Fraine et al 2013;Narita et al 2013;Teske et al 2013;Cáceres et al 2014;Gillon et al 2014;Kreidberg et al 2014;Wilson et al 2014;Nascimbeni et al 2015). A total of 58 measurements have been published for bandpasses with central wavelengths shorter than 9260Å, the longest wavelength in our Magellan/ IMACS spectrum.…”

Section: Previous Measurementsmentioning

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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Section: Previous Measurementsmentioning

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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“…Gibson et al 2012b;Waldmann 2012), along with the availability of more stable NIR cameras such as WFC3 (e.g. Berta et al 2012;Gibson et al 2012a).…”

Section: Introductionmentioning

confidence: 99%

A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720 nm

Gibson¹,

Aigrain²,

Barstow³

et al. 2012

Monthly Notices of the Royal Astronomical Society

136

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We report Gemini-South GMOS observations of the exoplanet system WASP-29 during primary transit as a test case for differential spectrophotometry. We use the multi-object spectrograph to observe the target star and a comparison star simultaneously to produce multiple light curves at varying wavelengths. The 'white' light curve and fifteen 'spectral' light curves are analysed to refine the system parameters and produce a transmission spectrum from ∼515 to 720 nm. All light curves exhibit time-correlated noise, which we model using a variety of techniques. These include a simple noise rescaling, a Gaussian process model, and a wavelet based method. These methods all produce consistent results, although with different uncertainties. The precision of the transmission spectrum is improved by subtracting a common signal from all the spectral light curves, reaching a typical precision of ∼1×10 −4 in transit depth. The transmission spectrum is free of spectral features, and given the non-detection of a pressure broadened Na feature, we can rule out the presence of a Na rich atmosphere free of clouds or hazes, although we cannot rule out a narrow Na core. This indicates that Na is not present in the atmosphere, and/or that clouds/hazes play a significant role in the atmosphere and mask the broad wings of the Na feature, although the former is a more likely explanation given WASP-29b's equilibrium temperature of ∼970 K, at which Na can form various compounds. We also briefly discuss the use of Gaussian process and wavelet methods to account for time correlated noise in transit light curves.

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“…Transit spectroscopy is the ideal technique to probe temperate planets around M-dwarfs. These are by far the most common type of stars in our Galaxy, albeit much smaller, dimmer and cooler than stars like our sun: if the host star is bright enough, these objects are within reach the current or the near-term future facilities (Bean et al 2010;Berta et al 2012). For temperate planets around earlier-type stars, direct imaging will be a more appropriate technique as transit observations would be rather impractical in these cases.…”

Section: Overviewmentioning

confidence: 99%

“…Third row: NIR transit spectra recorded with NICMOS for XO1-b (left: and XO2-b (fourth row, Crouzet et al 2012) and interpretations. Bottom figure: available data from space and the ground and interpretation for GJ 1214b (Berta et al 2012, see also Bean et al 2010) observations were followed by other space and ground data Croll et al 2011;Crossfield et al 2011;Désert et al 2011;Berta et al 2012) which are suggestive of an atmosphere heavier than pure molecular hydrogen, but additional observations are needed to confirm its composition (see Fig. 6).…”

Section: Primary Transit Observationsmentioning

confidence: 99%

Spectroscopy of planetary atmospheres in our Galaxy

Tinetti

Encrenaz

Coustenis

2013

Astron Astrophys Rev

124

110

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About 20 years after the discovery of the first extrasolar planet, the number of planets known has grown by three orders of magnitude, and continues to increase at neck breaking pace. For most of these planets we have little information, except for the fact that they exist and possess an address in our Galaxy. For about one third of them, we know how much they weigh, their size and their orbital parameters. For less than 20, we start to have some clues about their atmospheric temperature and composition. How do we make progress from here?We are still far from the completion of a hypothetical Hertzsprung-Russell diagram for planets comparable to what we have for stars, and today we do not even know whether such classification will ever be possible or even meaningful for planetary objects. But one thing is clear: planetary parameters such as mass, radius and temperature alone do not explain the diversity revealed by current observations. The chemical composition of these planets is needed to trace back their formation history and evolution, as happened for the planets in our Solar System. As in situ measurements are and will remain off-limits for exoplanets, to study their chemical composition we will have to rely on remote sensing spectroscopic observations of their gaseous envelopes.

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THE FLAT TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ1214b FROM WIDE FIELD CAMERA 3 ON THEHUBBLE SPACE TELESCOPE

Cited by 361 publications

References 85 publications

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

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

A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720 nm

Spectroscopy of planetary atmospheres in our Galaxy

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