The GTC exoplanet transit spectroscopy survey

Chen, G.; Πάλλη, Ε.; Nortmann, L.; Murgas, F.; Parviainen, H.; Nowak, G.

doi:10.1051/0004-6361/201730736

Cited by 56 publications

(55 citation statements)

References 44 publications

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“…4.3, respectively. Chen et al (2017) obtained an absorption depth of ∆F/F = 0.378 ± 0.068% in a 16 Å band at Na with GTC low-resolution transmission spectrum, where the Na doublet is unresolved. For comparison, we integrated the ESPRESSO transmission spectrum over a 16-Å passband centered at the Na doublet (A ≈ 0.62%), and convolved it with a Gaussian kernel.…”

Section: Binned Absorption Depthmentioning

confidence: 98%

Detection of Na, K, and Hαabsorption in the atmosphere of WASP-52b using ESPRESSO

Chen

Casasayas-Barris

Πάλλη

et al. 2020

A&A

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WASP-52b is a low density hot Jupiter orbiting a moderately active K2V star. Previous low-resolution studies have revealed a cloudy atmosphere and found atomic Na above the cloud deck. Here we report the detection of excess absorption at the Na doublet, the Hα line, and the K D 1 line. We derived a high-resolution transmission spectrum based on three transits of WASP-52b, observed with the ultra stable, high-resolution spectrograph ESPRESSO at the VLT. We measure a line contrast of 1.09 ± 0.16% for Na D 1 , 1.31 ± 0.13% for Na D 2 , 0.86 ± 0.13% for Hα, and 0.46 ± 0.13% for K D 1 , with a line FWHM range of 11-22 km s −1 . We also find that the velocity shift of these detected lines during the transit is consistent with the planet orbital motion, thus confirming their planetary origin. We do not observe any significant net blueshift or redshift that can be attributed to planetary winds. We use activity indicator lines as control but find no excess absorption. However, we do notice signatures arising from the Center-to-Limb variation (CLV) and the Rossiter-McLaughlin (RM) effect at these control lines. This highlights the importance of the CLV+RM correction in correctly deriving the transmission spectrum, which, if not corrected, could resemble or cancel out planetary absorption in certain cases. WASP-52b is the second non-ultra-hot Jupiter to show excess Hα absorption, after HD 189733b. Future observations targeting non-ultra-hot Jupiters that show Hα could help reveal the relation between stellar activity and the heating processes in the planetary upper atmosphere.

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Section: Binned Absorption Depthmentioning

confidence: 98%

Detection of Na, K, and Hαabsorption in the atmosphere of WASP-52b using ESPRESSO

Chen

Casasayas-Barris

Πάλλη

et al. 2020

A&A

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“…Most recently, Louden et al (2017) used spectroscopy between 4000 and 8750 Å for two transit observations from the ACAM instrument mounted on the William Herschel Telescope (WHT). Chen et al (2017) observed one transit with the Gran Telescopio Canarias's (GTC) OSIRIS instrument in the 5220−9030 Å wavelength range. We show these transmission spectra compared to our STIS+Spitzer results in Figure 9.…”

Section: Comparison With Previous Resultsmentioning

confidence: 99%

“…We acquired 135 out-of-transit R-band images over the 2014-2015, 2015-2016, and 2016-2017 observing seasons with Tennessee State University's 14-inch Celestron Automatic Imaging Telescope (AIT). These observations, however, do not include the epochs of the Spitzer and groundbased (Chen et al 2017;Louden et al 2017) transit observations. We therefore used 740 out-of-transit V -band images from Ohio State University's All-Sky Automated Survey for Supernovae 2 (ASAS-SN) program (Shappee et al 2014;Kochanek et al 2017) for more detailed activity monitoring coverage.…”

Section: Stellar Variability Monitoringmentioning

confidence: 99%

The HST PanCET Program: Hints of Na i and Evidence of a Cloudy Atmosphere for the Inflated Hot Jupiter WASP-52b

Alam

Nikolov

López‐Morales

et al. 2018

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We present an optical to near-infrared transmission spectrum of the inflated hot Jupiter WASP-52b using three transit observations from the Space Telescope Imaging Spectrograph (STIS) mounted on the Hubble Space Telescope, combined with Spitzer/Infrared Array Camera (IRAC) photometry at 3.6 µm and 4.5 µm. Since WASP-52 is a moderately active (log(L x /L bol ) = −4.7) star, we correct the transit light curves for the effect of stellar activity using ground-based photometric monitoring data from the All-Sky Automated Survey for Supernovae (ASAS-SN) and Tennessee State University's Automatic Imaging Telescope (AIT). We bin the data in 38 spectrophotometric light curves from 0.29 to 4.5 µm and measure the transit depths to a median precision of 90 ppm. We compare the transmission spectrum to a grid of forward atmospheric models and find that our results are consistent with a cloudy spectrum and evidence of sodium at 2.3σ confidence, but no observable evidence of potassium absorption even in the narrowest spectroscopic channel. We find that the optical transmission spectrum of WASP-52b is similar to that of the well-studied inflated hot Jupiter HAT-P-1b, which has comparable surface gravity, equilibrium temperature, mass, radius, and stellar irradiation levels. At longer wavelengths, however, the best fitting models for WASP-52b and HAT-P-1b predict quite dissimilar properties, which could be confirmed with observations at wavelengths longer than ∼1 µm. The identification of planets with common atmospheric properties and similar system parameters will be insightful for comparative atmospheric studies with the James Webb Space Telescope.

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“…All the tested models present a synthetic transit model with a time dependency to reproduce a second-order color effect not corrected by the differential photometry, and a FWHM dependent polynomial to model the systematic effects produced by seeing variations. The FWHM correction was introduced because seeing variations affected the number of pixels in which the major part of the stellar flux is contained, and this pixel-dependent effect will act as a systematic correlated with FWHM (see Nortmann et al 2016;Chen et al 2017). With a slit 40 arcsec in width, the flux losses produced by not being able to measure the flux contained in the wings of the spectral profile are negligible.…”

Section: Model Selectionmentioning

confidence: 99%

“…The principle of transmission spectroscopy is to measure the change in the planetary radius at different wavelengths during a transit event, and to use this change to infer the presence of particular components of the exoplanet atmosphere. Because of their relatively big atmospheric scale heights, hot Jupiters are excellent targets for atmospheric detection from the ground and they are the main targets of our survey (e.g., Murgas et al 2014;Parviainen et al 2016;Pallé et al 2016;Nortmann et al 2016;Chen et al 2017).…”

Section: Introductionmentioning

confidence: 99%

The GTC exoplanet transit spectroscopy survey

Murgas

Πάλλη

Parviainen

et al. 2017

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Context. Transiting planets offer an excellent opportunity for characterizing the atmospheres of extrasolar planets under very different conditions from those found in our solar system. Aims. We are currently carrying out a ground-based survey to obtain the transmission spectra of several extrasolar planets using the 10 m Gran Telescopio Canarias. In this paper we investigate the extrasolar planet WASP-48b, a hot Jupiter orbiting around an F-type star with a period of 2.14 days. Methods. We obtained long-slit optical spectroscopy of one transit of WASP-48b with the Optical System for Imaging and lowIntermediate-Resolution Integrated Spectroscopy (OSIRIS) spectrograph. We integrated the spectrum of WASP-48 and one reference star in several channels with different wavelength ranges, creating numerous color light curves of the transit. We fit analytic transit curves to the data taking into account the systematic effects present in the time series in an effort to measure the change of the planetto-star radius ratio (R p /R s ) across wavelength. The change in transit depth can be compared with atmosphere models to infer the presence of particular atomic or molecular compounds in the atmosphere of WASP-48b. Results. After removing the transit model and systematic trends to the curves we reached precisions between 261 ppm and 455-755 ppm for the white and spectroscopic light curves, respectively. We obtained R p /R s uncertainty values between 0.8 × 10 −3 and 1.5 × 10 −3 for all the curves analyzed in this work. The measured transit depth for the curves made by integrating the wavelength range between 530 nm and 905 nm is in agreement with previous studies. We report a relatively flat transmission spectrum for WASP-48b with no statistical significant detection of atmospheric species, although the theoretical models that fit the data more closely include TiO and VO.

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The GTC exoplanet transit spectroscopy survey

Cited by 56 publications

References 44 publications

Detection of Na, K, and Hαabsorption in the atmosphere of WASP-52b using ESPRESSO

Detection of Na, K, and Hαabsorption in the atmosphere of WASP-52b using ESPRESSO

The HST PanCET Program: Hints of Na i and Evidence of a Cloudy Atmosphere for the Inflated Hot Jupiter WASP-52b

The GTC exoplanet transit spectroscopy survey

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