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N P Gibson - One of the best experts on this subject based on the ideXlab platform.
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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, David K Sing, Jonathan J. Fortney, N Nikolov, N P Gibson, F Pont, Gilda E Ballester, P. A. Wilson, Adam BurrowsAbstract: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.
Adam Burrows - One of the best experts on this subject based on the ideXlab platform.
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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, David K Sing, Jonathan J. Fortney, N Nikolov, N P Gibson, F Pont, Gilda E Ballester, P. A. Wilson, Adam BurrowsAbstract: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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photometric and spectral signatures of three dimensional models of transiting giant exoplanets
The Astrophysical Journal, 2010Co-Authors: Adam Burrows, Emily Rauscher, David S Spiegel, Kristen MenouAbstract:Using a three-dimensional general circulation model, we create dynamical model Atmospheres of a representative transiting giant exoplanet, HD 209458b. We post-process these Atmospheres with an opacity code to obtain transit radius spectra during the primary transit. Using a spectral Atmosphere code, we integrate over the face of the planet seen by an observer at various orbital phases and calculate light curves as a function of wavelength and for different photometric bands. The products of this study are generic predictions for the phase variations of a zero-eccentricity giant planet's transit spectrum and of its light curves. We find that for these models the temporal variations in all quantities and the ingress/egress contrasts in the transit radii are small (<1.0%). Moreover, we determine that the day/night contrasts and phase shifts of the brightness peaks relative to the ephemeris are functions of photometric band. The J, H, and K bands are shifted most, while the IRAC bands are shifted least. Therefore, we verify that the magnitude of the downwind shift in the planetary "hot spot" due to equatorial winds is strongly wavelength dependent. The phase and wavelength dependence of light curves, as well as the associated day/night contrasts, can be used to constrain the circulation regime of irradiated giant planets and to probe different pressure levels of a hot Jupiter Atmosphere. We posit that though our calculations focus on models of HD 209458b, similar calculations for other transiting hot Jupiters in low-eccentricity orbits should yield transit spectra and light curves of a similar character.
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photometric and spectral signatures of 3d models of transiting giant exoplanets
arXiv: Earth and Planetary Astrophysics, 2010Co-Authors: Adam Burrows, Emily Rauscher, David S Spiegel, Kristen MenouAbstract:Using a 3D GCM, we create dynamical model Atmospheres of a representative transiting giant exoplanet, HD 209458b. We post-process these Atmospheres with an opacity code to obtain transit radius spectra during the primary transit. Using a spectral Atmosphere code, we integrate over the face of the planet seen by an observer at various orbital phases and calculate light curves as a function of wavelength and for different photometric bands. The products of this study are generic predictions for the phase variations of a zero-eccentricity giant planet's transit spectrum and of its light curves. We find that for these models the temporal variations in all quantities and the ingress/egress contrasts in the transit radii are small ($< 1.0$\%). Moreover, we determine that the day/night contrasts and phase shifts of the brightness peaks relative to the ephemeris are functions of photometric band. The $J$, $H$, and $K$ bands are shifted most, while the IRAC bands are shifted least. Therefore, we verify that the magnitude of the downwind shift in the planetary ``hot spot" due to equatorial winds is strongly wavelength-dependent. The phase and wavelength dependence of light curves, and the associated day/night contrasts, can be used to constrain the circulation regime of irradiated giant planets and to probe different pressure levels of a hot Jupiter Atmosphere. We posit that though our calculations focus on models of HD 209458b similar calculations for other transiting hot Jupiters in low-eccentricity orbits should yield transit spectra and light curves of a similar character.
Kristen Menou - One of the best experts on this subject based on the ideXlab platform.
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photometric and spectral signatures of three dimensional models of transiting giant exoplanets
The Astrophysical Journal, 2010Co-Authors: Adam Burrows, Emily Rauscher, David S Spiegel, Kristen MenouAbstract:Using a three-dimensional general circulation model, we create dynamical model Atmospheres of a representative transiting giant exoplanet, HD 209458b. We post-process these Atmospheres with an opacity code to obtain transit radius spectra during the primary transit. Using a spectral Atmosphere code, we integrate over the face of the planet seen by an observer at various orbital phases and calculate light curves as a function of wavelength and for different photometric bands. The products of this study are generic predictions for the phase variations of a zero-eccentricity giant planet's transit spectrum and of its light curves. We find that for these models the temporal variations in all quantities and the ingress/egress contrasts in the transit radii are small (<1.0%). Moreover, we determine that the day/night contrasts and phase shifts of the brightness peaks relative to the ephemeris are functions of photometric band. The J, H, and K bands are shifted most, while the IRAC bands are shifted least. Therefore, we verify that the magnitude of the downwind shift in the planetary "hot spot" due to equatorial winds is strongly wavelength dependent. The phase and wavelength dependence of light curves, as well as the associated day/night contrasts, can be used to constrain the circulation regime of irradiated giant planets and to probe different pressure levels of a hot Jupiter Atmosphere. We posit that though our calculations focus on models of HD 209458b, similar calculations for other transiting hot Jupiters in low-eccentricity orbits should yield transit spectra and light curves of a similar character.
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photometric and spectral signatures of 3d models of transiting giant exoplanets
arXiv: Earth and Planetary Astrophysics, 2010Co-Authors: Adam Burrows, Emily Rauscher, David S Spiegel, Kristen MenouAbstract:Using a 3D GCM, we create dynamical model Atmospheres of a representative transiting giant exoplanet, HD 209458b. We post-process these Atmospheres with an opacity code to obtain transit radius spectra during the primary transit. Using a spectral Atmosphere code, we integrate over the face of the planet seen by an observer at various orbital phases and calculate light curves as a function of wavelength and for different photometric bands. The products of this study are generic predictions for the phase variations of a zero-eccentricity giant planet's transit spectrum and of its light curves. We find that for these models the temporal variations in all quantities and the ingress/egress contrasts in the transit radii are small ($< 1.0$\%). Moreover, we determine that the day/night contrasts and phase shifts of the brightness peaks relative to the ephemeris are functions of photometric band. The $J$, $H$, and $K$ bands are shifted most, while the IRAC bands are shifted least. Therefore, we verify that the magnitude of the downwind shift in the planetary ``hot spot" due to equatorial winds is strongly wavelength-dependent. The phase and wavelength dependence of light curves, and the associated day/night contrasts, can be used to constrain the circulation regime of irradiated giant planets and to probe different pressure levels of a hot Jupiter Atmosphere. We posit that though our calculations focus on models of HD 209458b similar calculations for other transiting hot Jupiters in low-eccentricity orbits should yield transit spectra and light curves of a similar character.
Reijo Karjalainen - One of the best experts on this subject based on the ideXlab platform.
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Rayleigh scattering in the transmission spectrum of HAT-P-18b
Monthly Notices of the Royal Astronomical Society, 2017Co-Authors: James Kirk, Tom Louden, Peter J. Wheatley, Ian Skillen, P G J Irwin, A. P. Doyle, James Mccormac, Reijo KarjalainenAbstract:We have performed ground-based transmission spectroscopy of the hot Jupiter HAT-P-18b using the ACAM instrument on the William Herschel Telescope (WHT). Differential spectroscopy over an entire night was carried out at a resolution of R ≈ 400 using a nearby comparison star. We detect a blueward slope extending across our optical transmission spectrum that runs from 4750 to 9250 A. The slope is consistent with Rayleigh scattering at the equilibrium temperature of the planet (852 K). We do not detect enhanced sodium absorption, which indicates that a high-altitude haze is masking the feature and giving rise to the Rayleigh slope. This is only the second discovery of a Rayleigh-scattering slope in a hot Jupiter Atmosphere from the ground, and our study illustrates how ground-based observations can provide transmission spectra with precision comparable to the Hubble Space Telescope.
James Kirk - One of the best experts on this subject based on the ideXlab platform.
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Rayleigh scattering in the transmission spectrum of HAT-P-18b
Monthly Notices of the Royal Astronomical Society, 2017Co-Authors: James Kirk, Tom Louden, Peter J. Wheatley, Ian Skillen, P G J Irwin, A. P. Doyle, James Mccormac, Reijo KarjalainenAbstract:We have performed ground-based transmission spectroscopy of the hot Jupiter HAT-P-18b using the ACAM instrument on the William Herschel Telescope (WHT). Differential spectroscopy over an entire night was carried out at a resolution of R ≈ 400 using a nearby comparison star. We detect a blueward slope extending across our optical transmission spectrum that runs from 4750 to 9250 A. The slope is consistent with Rayleigh scattering at the equilibrium temperature of the planet (852 K). We do not detect enhanced sodium absorption, which indicates that a high-altitude haze is masking the feature and giving rise to the Rayleigh slope. This is only the second discovery of a Rayleigh-scattering slope in a hot Jupiter Atmosphere from the ground, and our study illustrates how ground-based observations can provide transmission spectra with precision comparable to the Hubble Space Telescope.
