Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b

Awiphan, S.; Kerins, E.; Pichadee, S.; Komonjinda, S.; Dhillon, V. S.; Rujopakarn, W.; Poshyachinda, S.; Marsh, T. R.; Reichart, D. E.; Ivarsen, K.; Haislip, J.

doi:10.1093/mnras/stw2148

Cited by 60 publications

(26 citation statements)

References 46 publications

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“…The mid-transit time T mid and the coefficients (c j , c k ) of the systematics baseline models were Run dependent. The derived transit parameters are given in Table 2, which are fully consistent with the ones obtained by the Spitzer observations in the 4.5 µm band and other literature studies (see Table 2 of Awiphan et al 2016). -Secondly, we fixed (i, a/R , T mid ) to the values listed in Table 2 and fit R p /R individually.…”

Section: Fitting Of White-color Light Curvessupporting

confidence: 88%

“…Nascimbeni et al (2013) analyzed their high-quality light curves simultaneously obtained by two Large Binocular Cameras (LBC) at the Large Binocular Telescope (LBT), and found that the planet radius is 9.7 ± 1.9% larger in the ultraviolet (λ c = 357.5 nm) than in the red-optical (λ c = 963.5 nm), which, together with Fukui et al (2013)'s measurements, was interpreted as a signature of scattering processes. Since then, several follow-up multi-epoch optical photometric studies (Biddle et al 2014;Dragomir et al 2015;Awiphan et al 2016) have reported tentative evidence of Rayleigh scattering in GJ 3470b. Crossfield et al (2013) performed the first transmission spectroscopy for GJ 3470b in the 2.09-2.36 µm band with the MOSFIRE spectrograph at the Keck telescope, and obtained a flat transmission spectrum.…”

Section: Introductionmentioning

confidence: 99%

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The GTC exoplanet transit spectroscopy survey

Chen

Guenther

Pallé

et al. 2017

A&A

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Aims. As a sub-Uranus-mass low-density planet, GJ 3470b has been found to show a flat featureless transmission spectrum in the infrared and a tentative Rayleigh scattering slope in the optical. We conducted an optical transmission spectroscopy project to assess the impacts of stellar activity and to determine whether or not GJ 3470b hosts a hydrogen-rich gas envelop. Methods. We observed three transits with the low-resolution Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) at the 10.4 m Gran Telescopio Canarias, and one transit with the high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) at the 8.2 m Very Large Telescope. Results. From the high-resolution data, we find that the difference of the Ca ii H+K lines in-and out-of-transit is only 0.67 ± 0.22%, and determine a magnetic filling factor of about 10-15%. From the low-resolution data, we present the first optical transmission spectrum in the 435-755 nm band, which shows a slope consistent with Rayleigh scattering. Conclusions. After exploring the potential impacts of stellar activity in our observations, we confirm that Rayleigh scattering in an extended hydrogen-helium atmosphere is currently the best explanation. Further high-precision observations that simultaneously cover optical and infrared bands are required to answer whether or not clouds and hazes exist at high-altitude.

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Section: Fitting Of White-color Light Curvessupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

The GTC exoplanet transit spectroscopy survey

Chen

Guenther

Pallé

et al. 2017

A&A

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“…However, there is evidence that many M dwarfs show a large number of small spots (Jackson & Jeffries 2012, 2013, which would greatly reduce the effect of spot activity because the occulted part of the stellar surface would be very similar to the unocculted areas. This is consistent with the lack of starspot features seen in transits of planets in front of M dwarfs (e.g., Mancini et al 2014;Awiphan et al 2016).…”

Section: Stellar Activitysupporting

confidence: 84%

Detection of the Atmosphere of the 1.6 M_⊕ Exoplanet GJ 1132 b

Southworth

Mancini

Madhusudhan

et al. 2017

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Detecting the atmospheres of low-mass, low-temperature exoplanets is a high-priority goal on the path to ultimately detecting biosignatures in the atmospheres of habitable exoplanets. High-precision HST observations of several super-Earths with equilibrium temperatures below 1000 K have to date all resulted in featureless transmission spectra, which have been suggested to be due to high-altitude clouds. We report the detection of an atmospheric feature in the atmosphere of a 1.6 M Å transiting exoplanet, GJ 1132 b, with an equilibrium temperature of ∼600 K and orbiting a nearby M dwarf. We present observations of nine transits of the planet obtained simultaneously in the griz and JHK passbands. We find an average radius of 1.43±0.16 R Å for the planet, averaged over all the passbands, and a radius of 0.255±0.023 R  for the star, both of which are significantly greater than previously found. The planet radius can be decomposed into a "surface radius" at ∼1.375 R Å overlaid by atmospheric features that increase the observed radius in the z and K bands. The z-band radius is 4σ higher than the continuum, suggesting a strong detection of an atmosphere. We deploy a suite of tests to verify the reliability of the transmission spectrum, which are greatly helped by the existence of repeat observations. The large z-band transit depth indicates strong opacity from H 2 O and/or CH 4 or a hitherto-unconsidered opacity. A surface radius of 1.375±0.16 R Å allows for a wide range of interior compositions ranging from a nearly Earth-like rocky interior, with ∼70% silicate and ∼30% Fe, to a substantially H 2 O-rich water world.

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“…GJ 436b is also reported as showing a featureless spectrum in the near-infrared by Knutson et al (2014), suggesting the presence of a cloudy/hazy layer. GJ 3470b is reported to show a bit more complicated spectrum, which includes a steep spectral slope 1 in the optical Nascimbeni et al 2013;Biddle et al 2014;Dragomir et al 2015;Awiphan et al 2016) and is relatively featureless or flat in the near-infrared (Crossfield et al 2013;Ehrenreich et al 2014). A modest amount of cloud/haze particles, if present, tend to steepen the spectral slope in the optical (Lecavelier Des Etangs et al 2008), while a thick cloud/haze obscures molecular and atomic absorption features, flattening the spectrum.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Transmission Spectra of Exoplanet Atmospheres with Hydrocarbon Haze: Effect of Creation, Growth, and Settling of Haze Particles. I. Model Description and First Results

Kawashima¹,

Ikoma

2018

ApJ

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Recently, properties of exoplanet atmospheres have been constrained via multi-wavelength transit observation, which measures an apparent decrease in stellar brightness during planetary transit in front of its host star (called transit depth). Sets of transit depths so far measured at different wavelengths (called transmission spectra) are somewhat diverse: Some show steep spectral slope features in the visible, some contain featureless spectra in the near-infrared, some show distinct features from radiative absorption by gaseous species. These facts infer the existence of haze in the atmospheres especially of warm, relatively low-density super-Earths and mini-Neptunes. Previous studies that addressed theoretical modeling of transmission spectra of hydrogen-dominated atmospheres with haze used some assumed distribution and size of haze particles. In this study, we model the atmospheric chemistry, derive the spatial and size distributions of haze particles by simulating the creation, growth and settling of hydrocarbon haze particles directly, and develop transmission spectrum models of UVirradiated, solar-abundance atmospheres of close-in warm (∼ 500 K) exoplanets. We find that the haze is distributed in the atmosphere much more broadly than previously assumed and consists of particles of various sizes. We also demonstrate that the observed diversity of transmission spectra can be explained by the difference in the production rate of haze monomers, which is related to the UV irradiation intensity from host stars.

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Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b

Abstract: This is a repository copy of Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b.

Cited by 60 publications

References 46 publications

The GTC exoplanet transit spectroscopy survey

The GTC exoplanet transit spectroscopy survey

Detection of the Atmosphere of the 1.6 M_⊕ Exoplanet GJ 1132 b

Theoretical Transmission Spectra of Exoplanet Atmospheres with Hydrocarbon Haze: Effect of Creation, Growth, and Settling of Haze Particles. I. Model Description and First Results

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Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b

Abstract: This is a repository copy of Transit timing variation and transmission spectroscopy analyses of the hot Neptune GJ3470b.

Cited by 60 publications

References 46 publications

The GTC exoplanet transit spectroscopy survey

The GTC exoplanet transit spectroscopy survey

Detection of the Atmosphere of the 1.6 M⊕ Exoplanet GJ 1132 b

Theoretical Transmission Spectra of Exoplanet Atmospheres with Hydrocarbon Haze: Effect of Creation, Growth, and Settling of Haze Particles. I. Model Description and First Results

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Detection of the Atmosphere of the 1.6 M_⊕ Exoplanet GJ 1132 b