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Jonathan J. Fortney - One of the best experts on this subject based on the ideXlab platform.
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The transit Transmission Spectrum of a cold gas giant planet
The Astrophysical Journal, 2015Co-Authors: Paul A. Dalba, Jonathan J. Fortney, Philip S. Muirhead, Matthew M. Hedman, Philip D. Nicholson, Mark J. VeyetteAbstract:© 2015. The American Astronomical Society. All rights reserved.. We use solar occultations observed by the Visual and Infrared Mapping Spectrometer on board the Cassini Spacecraft to extract the 1-5 μm Transmission Spectrum of Saturn, as if it were a transiting exoplanet. We detect absorption from methane, ethane, acetylene, aliphatic hydrocarbons, and possibly carbon monoxide, with peak-to-peak features of up to 90 parts-per-million despite the presence of ammonia clouds. We also find that atmospheric refraction, as opposed to clouds or haze, determines the minimum altitude that could be probed during mid-transit. Self-consistent exoplanet atmosphere models show good agreement with Saturn's Transmission Spectrum but fail to reproduce a large absorption feature near 3.4 μm, likely caused by gaseous ethane and a C-H stretching mode of an unknown aliphatic hydrocarbon. This large feature is located in one of the Spitzer Space Telescope bandpasses and could alter interpretations of Transmission spectra if not properly modeled. The large signal in Saturn's Transmission Spectrum suggests that Transmission spectroscopy of cold, long-period gaseous exoplanets should be possible with current and future observatories. Motivated by these results, we briefly consider the feasibility of using a survey to search for and characterize cold exoplanets that are analogous to Jupiter and Saturn utilizing a target-of-opportunity approach.
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broad band Transmission Spectrum and k band thermal emission of wasp 43b as observed from the ground
Astronomy and Astrophysics, 2014Co-Authors: Jonathan J. Fortney, Wei Wang, R. Van Boekel, N Nikolov, G Chen, H Wang, U Seemann, L ManciniAbstract:Aims. WASP-43b is the closest-orbiting hot Jupiter, and it has high bulk density. It causes deep eclipse depths in the system's light curve in both transit and occultation that is attributed to the cool temperature and small radius of its host star. We aim to secure a broad-band Transmission Spectrum and to detect its near-infrared thermal emission in order to characterize its atmosphere.
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a ground based optical Transmission Spectrum of wasp 6b
The Astrophysical Journal, 2013Co-Authors: Andres Jordan, J M Desert, N Espinoza, M Rabus, S Eyheramendy, David K Sing, G A Bakos, Jonathan J. FortneyAbstract:We present a ground-based optical Transmission Spectrum of the inflated sub-Jupiter-mass planet WASP-6b. The Spectrum was measured in 20 spectral channels from 480 nm to 860 nm using a series of 91 spectra over a complete transit event. The observations were carried out using multi-object differential spectrophotometry with the Inamori-Magellan Areal Camera and Spectrograph on the Baade Telescope at Las Campanas Observatory. We model systematic effects on the observed light curves using principal component analysis on the comparison stars and allow for the presence of short and long memory correlation structure in our Monte Carlo Markov Chain analysis of the transit light curves for WASP-6. The measured Transmission Spectrum presents a general trend of decreasing apparent planetary size with wavelength and lacks evidence for broad spectral features of Na and K predicted by clear atmosphere models. The Spectrum is consistent with that expected for scattering that is more efficient in the blue, as could be caused by hazes or condensates in the atmosphere of WASP-6b. WASP-6b therefore appears to be yet another massive exoplanet with evidence for a mostly featureless Transmission Spectrum, underscoring the importance that hazes and condensates can have in determining the Transmission spectra of exoplanets.
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an hst optical to near ir Transmission Spectrum of the hot jupiter wasp 19b detection of atmospheric water and likely absence of tio
Monthly Notices of the Royal Astronomical Society, 2013Co-Authors: Catherine M Huitson, Jonathan J. Fortney, David K Sing, N Nikolov, N P Gibson, F Pont, Adam Burrows, P A Wilson, Gilda E BallesterAbstract:We measure the Transmission Spectrum of WASP-19b from three transits using low-resolution optical spectroscopy from the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS). The STIS spectra cover a wavelength range of 0.29-1.03 µm, with resolving power R = 500. The optical data are combined with archival near-infrared data from the HST Wide Field Camera 3 (WFC3) G141 grism, covering the wavelength range from 1.087 to 1.687 µm, with resolving power R = 130. We reach S/N levels between 3,000 and 11,000 in 0.1 µm bins when measuring the Transmission spectra from 0.53-1.687 µm. WASP-19 is known to be a very active star, with the optical stellar flux varying by a few per cent over time. We correct the transit light curves for the effects of stellar activity using ground-based activity monitoring with the Cerro Tololo Inter-American Observatory (CTIO). While we were not able to construct a Transmission Spectrum using the blue optical data because of the presence of large occulted star spots, we were able to use the spot crossings to help constrain the mean stellar spot temperature. To search for predicted features in the hot-Jupiter atmosphere, in addition to the Transmission Spectrum we also define spectral indices for differential radius (�RP/R⋆) measurements to specifically search for the presence of TiO and alkali line features. Our measurements rule out TiO features predicted for a planet of WASP-19b’s equilibrium temperature (2050 K) in the Transmission Spectrum at the 2.7-2.9 σ confidence level, depending on atmospheric model formalism. The WFC3 Transmission Spectrum shows strong absorption features due to the presence of H2O, which is detected at the 4 σ confidence level between 1.1 and 1.4 µm. The Transmission spectra results indicate that WASP-19b is a planet with no or low levels of TiO and without a high C/O ratio. The lack of observable TiO features are possibly due to rainout, breakdown from stellar activity or the presence of other absorbers in the optical.
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quantitatively assessing the role of clouds in the Transmission Spectrum of gj 1214b
The Astrophysical Journal, 2013Co-Authors: Caroline V Morley, Jonathan J. Fortney, Eliza M R Kempton, Mark S Marley, Channon Vissher, Kevin ZahnleAbstract:Recent observations of the super-Earth GJ?1214b show that it has a relatively featureless Transmission Spectrum. One suggestion is that these observations indicate that the planet's atmosphere is vertically compact, perhaps due to a water-rich composition that yields a large mean molecular weight. Another suggestion is that the atmosphere is hydrogen/helium-rich with clouds that obscure predicted absorption features. Previous models that incorporate clouds have included their effect without a strong physical motivation for their existence. Here, we present model atmospheres of GJ?1214b that include physically motivated clouds of two types. We model the clouds that are present in chemical equilibrium, as has been suggested to occur on brown dwarfs, which include KCl and ZnS for this planet. We also include clouds that form as a result of photochemistry, forming a hydrocarbon haze layer. We use a photochemical kinetics model to understand the vertical distribution and available mass of haze-forming molecules. We model both solar and enhanced-metallicity cloudy models and determine the cloud properties necessary to match observations. In enhanced-metallicity atmospheres, we find that the equilibrium clouds can match the observations of GJ?1214b if they are lofted high into the atmosphere and have a low sedimentation efficiency (f sed = 0.1). We find that models with a variety of hydrocarbon haze properties can match the observations. Particle sizes from 0.01 to 0.25 ?m can match the Transmission Spectrum with haze-forming efficiencies as low as 1%-5%.
J M Desert - One of the best experts on this subject based on the ideXlab platform.
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the hubble space telescope pancet program an optical to infrared Transmission Spectrum of hat p 32ab
The Astronomical Journal, 2020Co-Authors: Munazza K Alam, J M Desert, David K Sing, Thomas Mikalevans, Gregory W. Henry, Joanna K Barstow, Mercedes Lopezmorales, N Nikolov, Claire Baxter, V BourrierAbstract:We present a 0.3-5 micron Transmission Spectrum of the hot Jupiter HAT-P-32Ab observed with the Space Telescope Imaging Spectrograph (STIS) and Wide Field Camera 3 (WFC3) instruments mounted on the Hubble Space Telescope, combined with Spitzer Infrared Array Camera (IRAC) photometry. The Spectrum is composed of 51 spectrophotometric bins with widths ranging between 150 and 400 A, measured to a median precision of 215 ppm. Comparisons of the observed Transmission Spectrum to a grid of 1D radiative-convective equilibrium models indicate the presence of clouds/hazes, consistent with previous transit observations and secondary eclipse measurements. To provide more robust constraints on the planet's atmospheric properties, we perform the first full optical to infrared retrieval analysis for this planet. The retrieved Spectrum is consistent with a limb temperature of 1248$\pm$92 K, a thick cloud deck, enhanced Rayleigh scattering, and $\sim$10x solar H2O abundance. We find log($Z/Z_{\odot}$) = 2.41$_{-0.07}^{+0.06}$, in agreement with the mass-metallicity relation derived for the Solar System.
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the hst pancet program an optical to infrared Transmission Spectrum of hat p 32ab
arXiv: Earth and Planetary Astrophysics, 2020Co-Authors: Munazza K Alam, J M Desert, David K Sing, Thomas Mikalevans, Gregory W. Henry, Joanna K Barstow, Mercedes Lopezmorales, N Nikolov, Claire Baxter, V BourrierAbstract:We present a 0.3-5 micron Transmission Spectrum of the hot Jupiter HAT-P-32Ab observed with the Space Telescope Imaging Spectrograph (STIS) and Wide Field Camera 3 (WFC3) instruments mounted on the Hubble Space Telescope, combined with Spitzer Infrared Array Camera (IRAC) photometry. The Spectrum is composed of 51 spectrophotometric bins with widths ranging between 150 and 400 A, measured to a median precision of 215 ppm. Comparisons of the observed Transmission Spectrum to a grid of 1D radiative-convective equilibrium models indicate the presence of clouds/hazes, consistent with previous transit observations and secondary eclipse measurements. To provide more robust constraints on the planet's atmospheric properties, we perform the first full optical to infrared retrieval analysis for this planet. The retrieved Spectrum is consistent with a limb temperature of 1248$\pm$92 K, a thick cloud deck, enhanced Rayleigh scattering, and $\sim$10x solar H2O abundance. We find log($Z/Z_{\odot}$) = 2.41$_{-0.07}^{+0.06}$, in agreement with the mass-metallicity relation derived for the Solar System.
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A Near-infrared Transmission Spectrum for the Warm Saturn HAT-P-12b
The Astrophysical Journal, 2013Co-Authors: Michael R. Line, Heather A. Knutson, Drake Deming, Ashlee Wilkins, J M DesertAbstract:We present a Hubble Space Telescope Wide Field Camera-3 (WFC3) Transmission Spectrum for the transiting exoplanet HAT-P-12b. This warm (1000 K) sub-Saturn-mass planet has a smaller mass and a lower temperature than the hot Jupiters that have been studied so far. We find that the planet's measured Transmission Spectrum lacks the expected water absorption feature for a hydrogen-dominated atmosphere and is instead best described by a model with high-altitude clouds. Using a frequentist hypothesis testing procedure, we can rule out a hydrogen-dominated cloud-free atmosphere to 4.9σ. When combined with other recent WFC3 studies, our observations suggest that clouds may be common in exoplanetary atmospheres.
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a ground based optical Transmission Spectrum of wasp 6b
The Astrophysical Journal, 2013Co-Authors: Andres Jordan, J M Desert, N Espinoza, M Rabus, S Eyheramendy, David K Sing, G A Bakos, Jonathan J. FortneyAbstract:We present a ground-based optical Transmission Spectrum of the inflated sub-Jupiter-mass planet WASP-6b. The Spectrum was measured in 20 spectral channels from 480 nm to 860 nm using a series of 91 spectra over a complete transit event. The observations were carried out using multi-object differential spectrophotometry with the Inamori-Magellan Areal Camera and Spectrograph on the Baade Telescope at Las Campanas Observatory. We model systematic effects on the observed light curves using principal component analysis on the comparison stars and allow for the presence of short and long memory correlation structure in our Monte Carlo Markov Chain analysis of the transit light curves for WASP-6. The measured Transmission Spectrum presents a general trend of decreasing apparent planetary size with wavelength and lacks evidence for broad spectral features of Na and K predicted by clear atmosphere models. The Spectrum is consistent with that expected for scattering that is more efficient in the blue, as could be caused by hazes or condensates in the atmosphere of WASP-6b. WASP-6b therefore appears to be yet another massive exoplanet with evidence for a mostly featureless Transmission Spectrum, underscoring the importance that hazes and condensates can have in determining the Transmission spectra of exoplanets.
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the flat Transmission Spectrum of the super earth gj1214b from wide field camera 3 on the hubble space telescope
The Astrophysical Journal, 2012Co-Authors: Zachory K Berta, David Charbonneau, Peter R. Mccullough, Jonathan Irwin, J M Desert, Christopher J Burke, Jonathan J. Fortney, Eliza M R Kempton, Philip NutzmanAbstract:Capitalizing on the observational advantage oered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the Transmission Spectrum of the super-Earth exoplanet GJ1214b. These are the rst published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, nding the Transmission Spectrum of GJ1214b to be at between 1.1 and 1.7 m. Inconsistent with a cloud-free solar composition atmosphere at 8:2 , the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b’s outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the at Transmission Spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 m in diameter. Subject headings: planetary systems: individual (GJ 1214b) | eclipses | techniques: spectroscopic
Zachory K Berta - One of the best experts on this subject based on the ideXlab platform.
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the flat Transmission Spectrum of the super earth gj1214b from wide field camera 3 on the hubble space telescope
The Astrophysical Journal, 2012Co-Authors: Zachory K Berta, David Charbonneau, Peter R. Mccullough, Jonathan Irwin, J M Desert, Christopher J Burke, Jonathan J. Fortney, Eliza M R Kempton, Philip NutzmanAbstract:Capitalizing on the observational advantage oered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the Transmission Spectrum of the super-Earth exoplanet GJ1214b. These are the rst published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, nding the Transmission Spectrum of GJ1214b to be at between 1.1 and 1.7 m. Inconsistent with a cloud-free solar composition atmosphere at 8:2 , the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b’s outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the at Transmission Spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 m in diameter. Subject headings: planetary systems: individual (GJ 1214b) | eclipses | techniques: spectroscopic
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The flat Transmission Spectrum of the super-earth GJ1214b from wide field camera 3 on the Hubble space telescope
Astrophysical Journal, 2012Co-Authors: Zachory K Berta, David Charbonneau, Eliza Miller-ricci Kempton, Peter R. Mccullough, Jonathan Irwin, Philip Nutzman, J M Desert, Christopher J Burke, Jonathan J. Fortney, Derek HomeierAbstract:Capitalizing on the observational advantage offered by its tiny M dwarf host, we present Hubble Space Telescope/Wide Field Camera 3 (WFC3) grism measurements of the Transmission Spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the Transmission Spectrum of GJ1214b to be flat between 1.1 and 1.7 μm. Inconsistent with a cloud-free solar composition atmosphere at 8.2σ, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat Transmission Spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 μm in diameter.
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the optical and near infrared Transmission Spectrum of the super earth gj 1214b further evidence for a metal rich atmosphere
The Astrophysical Journal, 2011Co-Authors: Jacob L Bean, Zachory K Berta, J M Desert, Eliza M R Kempton, D Homeier, P Kabath, B Stalder, Sara Seager, Shane Walsh, Andreas SeifahrtAbstract:We present an investigation of the Transmission Spectrum of the 6.5 M ? planet GJ?1214b based on new ground-based observations of transits of the planet in the optical and near-infrared, and on previously published data. Observations with the VLT + FORS and Magellan + MMIRS using the technique of multi-object spectroscopy with wide slits yielded new measurements of the planet's Transmission Spectrum from 0.61 to 0.85 ?m, and in the J, H, and K atmospheric windows. We also present a new measurement based on narrow-band photometry centered at 2.09 ?m with the VLT + HAWKI. We combined these data with results from a reanalysis of previously published FORS data from 0.78 to 1.00 ?m using an improved data reduction algorithm, and previously reported values based on Spitzer data at 3.6 and 4.5 ?m. All of the data are consistent with a featureless Transmission Spectrum for the planet. Our K-band data are inconsistent with the detection of spectral features at these wavelengths reported by Croll and collaborators at the level of 4.1?. The planet's atmosphere must either have at least 70% H2O by mass or optically thick high-altitude clouds or haze to be consistent with the data.
Eliza M R Kempton - One of the best experts on this subject based on the ideXlab platform.
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quantitatively assessing the role of clouds in the Transmission Spectrum of gj 1214b
The Astrophysical Journal, 2013Co-Authors: Caroline V Morley, Jonathan J. Fortney, Eliza M R Kempton, Mark S Marley, Channon Vissher, Kevin ZahnleAbstract:Recent observations of the super-Earth GJ?1214b show that it has a relatively featureless Transmission Spectrum. One suggestion is that these observations indicate that the planet's atmosphere is vertically compact, perhaps due to a water-rich composition that yields a large mean molecular weight. Another suggestion is that the atmosphere is hydrogen/helium-rich with clouds that obscure predicted absorption features. Previous models that incorporate clouds have included their effect without a strong physical motivation for their existence. Here, we present model atmospheres of GJ?1214b that include physically motivated clouds of two types. We model the clouds that are present in chemical equilibrium, as has been suggested to occur on brown dwarfs, which include KCl and ZnS for this planet. We also include clouds that form as a result of photochemistry, forming a hydrocarbon haze layer. We use a photochemical kinetics model to understand the vertical distribution and available mass of haze-forming molecules. We model both solar and enhanced-metallicity cloudy models and determine the cloud properties necessary to match observations. In enhanced-metallicity atmospheres, we find that the equilibrium clouds can match the observations of GJ?1214b if they are lofted high into the atmosphere and have a low sedimentation efficiency (f sed = 0.1). We find that models with a variety of hydrocarbon haze properties can match the observations. Particle sizes from 0.01 to 0.25 ?m can match the Transmission Spectrum with haze-forming efficiencies as low as 1%-5%.
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the flat Transmission Spectrum of the super earth gj1214b from wide field camera 3 on the hubble space telescope
The Astrophysical Journal, 2012Co-Authors: Zachory K Berta, David Charbonneau, Peter R. Mccullough, Jonathan Irwin, J M Desert, Christopher J Burke, Jonathan J. Fortney, Eliza M R Kempton, Philip NutzmanAbstract:Capitalizing on the observational advantage oered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the Transmission Spectrum of the super-Earth exoplanet GJ1214b. These are the rst published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, nding the Transmission Spectrum of GJ1214b to be at between 1.1 and 1.7 m. Inconsistent with a cloud-free solar composition atmosphere at 8:2 , the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b’s outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the at Transmission Spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 m in diameter. Subject headings: planetary systems: individual (GJ 1214b) | eclipses | techniques: spectroscopic
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the optical and near infrared Transmission Spectrum of the super earth gj 1214b further evidence for a metal rich atmosphere
The Astrophysical Journal, 2011Co-Authors: Jacob L Bean, Zachory K Berta, J M Desert, Eliza M R Kempton, D Homeier, P Kabath, B Stalder, Sara Seager, Shane Walsh, Andreas SeifahrtAbstract:We present an investigation of the Transmission Spectrum of the 6.5 M ? planet GJ?1214b based on new ground-based observations of transits of the planet in the optical and near-infrared, and on previously published data. Observations with the VLT + FORS and Magellan + MMIRS using the technique of multi-object spectroscopy with wide slits yielded new measurements of the planet's Transmission Spectrum from 0.61 to 0.85 ?m, and in the J, H, and K atmospheric windows. We also present a new measurement based on narrow-band photometry centered at 2.09 ?m with the VLT + HAWKI. We combined these data with results from a reanalysis of previously published FORS data from 0.78 to 1.00 ?m using an improved data reduction algorithm, and previously reported values based on Spitzer data at 3.6 and 4.5 ?m. All of the data are consistent with a featureless Transmission Spectrum for the planet. Our K-band data are inconsistent with the detection of spectral features at these wavelengths reported by Croll and collaborators at the level of 4.1?. The planet's atmosphere must either have at least 70% H2O by mass or optically thick high-altitude clouds or haze to be consistent with the data.
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a ground based Transmission Spectrum of the super earth exoplanet gj 1214b
Nature, 2010Co-Authors: Eliza M R Kempton, Jacob L Bean, D HomeierAbstract:For many extrasolar planets — such as 'hot Jupiters' — measurements of the mass and radius are sufficient to allow the calculation of the planet's density and infer their bulk composition. But for the rather smaller 'super-Earths', things get complicated. For instance, the mass and radius of the recently discovered transiting super-Earth GJ1214b are known, but three distinct models for the planet's composition are consistent with the data. Additional information on the composition of the atmosphere is required if the uncertainty is to be reduced. Now a method that provides just that has been developed. A team using the Very Large Telescope in Chile's Atacama Desert has obtained a Transmission Spectrum for GJ1214b between 780 nanometres and 1,000 nanometres that rules out cloud-free atmospheres composed mainly of hydrogen. If the planet's atmosphere is hydrogen-dominated, it must be hazy — or there could be a dense water-vapour atmosphere. This new ground-based observing technique will make investigation of extrasolar planets much more practical, so expect more news of super-Earths in the months to come. Three distinct models for the recently discovered super-Earth (masses 2–10 times that of Earth) planet GJ 1214b that are consistent with its mass and radius have been suggested. Breaking the degeneracy between these models requires obtaining constraints on the planet's atmospheric composition. Here, a ground based measurement of the Transmission Spectrum of GJ 1214b between 780 and 1,000 nm is reported. The lack of features in this Spectrum rules out cloud free atmospheres composed primarily of hydrogen. If the planet's atmosphere is hydrogen-dominated, then it must contain clouds or hazes that are optically thick at pressures <200 mbar. Alternatively, the data are also consistent with the presence of a dense water vapour atmosphere. In contrast to planets with masses similar to that of Jupiter and higher, the bulk compositions of planets in the so-called super-Earth regime (masses 2–10 times that of the Earth) cannot be uniquely determined from a measurement of mass and radius alone. For these planets, there is a degeneracy between the mass and composition of both the interior and a possible atmosphere in theoretical models1,2. The recently discovered transiting super-Earth exoplanet GJ 1214b is one example of this problem3. Three distinct models for the planet that are consistent with its mass and radius have been suggested4. Breaking the degeneracy between these models requires obtaining constraints on the planet's atmospheric composition5,6. Here we report a ground-based measurement of the Transmission Spectrum of GJ 1214b between wavelengths of 780 and 1,000 nm. The lack of features in this Spectrum rules out (at 4.9σ confidence) cloud-free atmospheres composed primarily of hydrogen. If the planet's atmosphere is hydrogen-dominated, then it must contain clouds or hazes that are optically thick at the observed wavelengths at pressures less than 200 mbar. Alternatively, the featureless Transmission Spectrum is also consistent with the presence of a dense, water vapour atmosphere.
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A ground-based Transmission Spectrum of the super-Earth exoplanet GJ 1214b
Nature, 2010Co-Authors: Jacob L Bean, Eliza M R Kempton, Derek HomeierAbstract:For many extrasolar planets — such as 'hot Jupiters' — measurements of the mass and radius are sufficient to allow the calculation of the planet's density and infer their bulk composition. But for the rather smaller 'super-Earths', things get complicated. For instance, the mass and radius of the recently discovered transiting super-Earth GJ1214b are known, but three distinct models for the planet's composition are consistent with the data. Additional information on the composition of the atmosphere is required if the uncertainty is to be reduced. Now a method that provides just that has been developed. A team using the Very Large Telescope in Chile's Atacama Desert has obtained a Transmission Spectrum for GJ1214b between 780 nanometres and 1,000 nanometres that rules out cloud-free atmospheres composed mainly of hydrogen. If the planet's atmosphere is hydrogen-dominated, it must be hazy — or there could be a dense water-vapour atmosphere. This new ground-based observing technique will make investigation of extrasolar planets much more practical, so expect more news of super-Earths in the months to come. Three distinct models for the recently discovered super-Earth (masses 2–10 times that of Earth) planet GJ 1214b that are consistent with its mass and radius have been suggested. Breaking the degeneracy between these models requires obtaining constraints on the planet's atmospheric composition. Here, a ground based measurement of the Transmission Spectrum of GJ 1214b between 780 and 1,000 nm is reported. The lack of features in this Spectrum rules out cloud free atmospheres composed primarily of hydrogen. If the planet's atmosphere is hydrogen-dominated, then it must contain clouds or hazes that are optically thick at pressures
Philip Nutzman - One of the best experts on this subject based on the ideXlab platform.
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the flat Transmission Spectrum of the super earth gj1214b from wide field camera 3 on the hubble space telescope
The Astrophysical Journal, 2012Co-Authors: Zachory K Berta, David Charbonneau, Peter R. Mccullough, Jonathan Irwin, J M Desert, Christopher J Burke, Jonathan J. Fortney, Eliza M R Kempton, Philip NutzmanAbstract:Capitalizing on the observational advantage oered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the Transmission Spectrum of the super-Earth exoplanet GJ1214b. These are the rst published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, nding the Transmission Spectrum of GJ1214b to be at between 1.1 and 1.7 m. Inconsistent with a cloud-free solar composition atmosphere at 8:2 , the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b’s outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the at Transmission Spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 m in diameter. Subject headings: planetary systems: individual (GJ 1214b) | eclipses | techniques: spectroscopic
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The flat Transmission Spectrum of the super-earth GJ1214b from wide field camera 3 on the Hubble space telescope
Astrophysical Journal, 2012Co-Authors: Zachory K Berta, David Charbonneau, Eliza Miller-ricci Kempton, Peter R. Mccullough, Jonathan Irwin, Philip Nutzman, J M Desert, Christopher J Burke, Jonathan J. Fortney, Derek HomeierAbstract:Capitalizing on the observational advantage offered by its tiny M dwarf host, we present Hubble Space Telescope/Wide Field Camera 3 (WFC3) grism measurements of the Transmission Spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the Transmission Spectrum of GJ1214b to be flat between 1.1 and 1.7 μm. Inconsistent with a cloud-free solar composition atmosphere at 8.2σ, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat Transmission Spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 μm in diameter.