Rayleigh Scattering in the Atmosphere of the Warm Exo-Neptune Gj 3470b

Dragomir, Diana; Benneke, Björn; Pearson, Kyle A.; Crossfield, Ian J. M.; Eastman, Jason D.; Barman, Travis; Biddle, Lauren I.

doi:10.1088/0004-637x/814/2/102

Cited by 76 publications

(60 citation statements)

References 54 publications

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“…Fukui et al (2013) found variations in the transit depths in the J, I, and 4.5 µm bands that suggest that the atmospheric opacity varies with wavelength due to the absorption or scattering of stellar light by atmospheric molecules. Nascimbeni et al (2013) detected a transit depth difference between the ultraviolet and optical wavelengths also indicating a Rayleighscattering slope, confirmed by Biddle et al (2014); Chen et al (2017) and Dragomir et al (2015). Crossfield et al (2013) found a flat transmission spectrum in the K-band suggesting a hazy, methane-poor, or high-metallicity atmosphere.…”

Section: Target Systems and Stellar Parametersmentioning

confidence: 60%

Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits

Kosiarek

Crossfield

Hardegree-Ullman

et al. 2019

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We report improved masses, radii, and densities for four planets in two bright M-dwarf systems, K2-3 and GJ3470, derived from a combination of new radial velocity and transit observations. Supplementing K2 photometry with follow-up Spitzer transit observations refined the transit ephemerides of K2-3 b, c, and d by over a factor of 10. We analyze ground-based photometry from the Evryscope and Fairborn Observatory to determine the characteristic stellar activity timescales for our Gaussian Process fit, including the stellar rotation period and activity region decay timescale. The stellar rotation signals for both stars are evident in the radial velocity data and are included in our fit using a Gaussian process trained on the photometry. We find the masses of K2-3 b, K2-3 c and GJ3470 b to be 6.48 +0.99 −0.93 , 2.14 +1.08 −1.04 , and 12.58 +1.31 −1.28 M ⊕ respectively. K2-3 d was not significantly detected and has a 3σ upper limit of 2.80 M ⊕ . These two systems are training cases for future TESS systems; due to the low planet densities (ρ < 3.7 g cm −3 ) and bright host stars (K < 9 mag), they are among the best candidates for transmission spectroscopy in order to characterize the atmospheric compositions of small planets.

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Section: Target Systems and Stellar Parametersmentioning

confidence: 60%

Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits

Kosiarek

Crossfield

Hardegree-Ullman

et al. 2019

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“…Examples are the clear atmosphere of WASP-39b (Fischer et al 2016;Sing et al 2016;Nikolov et al 2016), the hazy atmo-Article number, page 1 of 21 arXiv:1810.02172v2 [astro-ph.EP] 6 Dec 2018 A&A proofs: manuscript no. main sphere of GJ3470b (Nascimbeni et al 2013;Dragomir et al 2015;Chen et al 2017), and the flat transmission spectrum for GJ1214b (Berta et al 2012;Kreidberg et al 2014;Nascimbeni et al 2015). However, since this research takes place at the edge of what can be detected, contradicting results regarding individual planets are reported in the literature as well.…”

Section: Introductionmentioning

confidence: 82%

Deciphering the atmosphere of HAT-P-12b: solving discrepant results

Alexoudi

Mallonn

Essen

et al. 2018

A&A

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Context. Two independent investigations of the atmosphere of the hot Jupiter HAT-P-12b by two different groups resulted in discrepant solutions. Using broad-band photometry from the ground, one study found a flat and featureless transmission spectrum that was interpreted as gray absorption by dense cloud coverage. The second study made use of Hubble Space Telescope (HST) observations and found Rayleigh scattering at optical wavelengths caused by haze. Aims. The main purpose of this work is to determine the source of this inconsistency and provide feedback to prevent similar discrepancies in future analyses of other exoplanetary atmospheres. Methods. We studied the observed discrepancy via two methods. With further broad-band observations in the optical wavelength regions, we strengthened the previous measurements in precision, and with a homogeneous reanalysis of the published data, we were able to assess the systematic errors and the independent analyses of the two different groups. Results. Repeating the analysis steps of both works, we found that deviating values for the orbital parameters are the reason for the aforementioned discrepancy. Our work showed a degeneracy of the planetary spectral slope with these parameters. In a homogeneous reanalysis of all data, the two literature data sets and the new observations converge to a consistent transmission spectrum, showing a low-amplitude spectral slope and a tentative detection of potassium absorption.

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“…Its near-infrared transmission spectrum shows no atmospheric features at the precision obtainable with HST/WFC3 in staring mode (Ehrenreich et al 2014) or from the ground (Crossfield et al 2013). In the optical, several studies point to a tentative increase in the planet radius towards short wavelengths (Fukui et al 2013;Nascimbeni et al 2013, Biddle et al 2014Dragomir et al 2015;Awiphan et al 2016;Chen et al 2017). As in HD 189733b, HD 209458b, WASP-6b, and HAT-P-12b (Lecavelier Des Etangs et al 2008a,c;Nikolov et al 2015;Sing et al 2016), this slope could be attributed to Rayleigh scattering in an extended atmosphere of molecular hydrogen and he- lium.…”

Section: Introductionmentioning

confidence: 99%

Hubble PanCET: an extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470b

Bourrier

Étangs

Ehrenreich

et al. 2018

A&A

161

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GJ 3470b is a warm Neptune transiting a M dwarf star at the edge of the evaporation desert. It offers the possibility to investigate how low-mass, close-in exoplanets evolve under the irradiation from their host stars. We observed three transits of GJ 3470b in the Lyman-α line with the Hubble Space Telescope (HST) as part of the Panchromatic Comparative Exoplanet Treasury (PanCET) program. Absorption signatures are detected with similar properties in all three independent epochs, with absorption depths of 35±7% in the blue wing of the line, and 23±5% in the red wing. The repeatability of these signatures, their phasing with the planet transit, and the radial velocity of the absorbing gas, allow us to conclude that there is an extended upper atmosphere of neutral hydrogen around GJ 3470 b. We determine from our observations the stellar radiation pressure and XUV irradiation from GJ 3470 and use them to perform numerical simulations of GJ 3470b's upper atmosphere with the EVaporating Exoplanets (EVE) code. The unusual redshifted signature can be explained by the damping wings of dense layers of neutral hydrogen extending beyond the Roche lobe and elongated in the direction of the planet motion. This structure could correspond to a shocked layer of planetary material formed by the collision of the expanding thermosphere with the wind of the star. The blueshifted signature is well explained by neutral hydrogen atoms escaping at rates of about 10 10 g s −1 , blown away from the star by its strong radiation pressure, and quickly photoionized, resulting in a smaller exosphere than that of the warm Neptune GJ 436b. The stronger escape from GJ 3470b, however, may have led to the loss of about 4-35% of its current mass over its ∼2 Gyr lifetime.

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Rayleigh Scattering in the Atmosphere of the Warm Exo-Neptune Gj 3470b

Cited by 76 publications

References 54 publications

Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits

Bright Opportunities for Atmospheric Characterization of Small Planets: Masses and Radii of K2-3 b, c, and d and GJ3470 b from Radial Velocity Measurements and Spitzer Transits

Deciphering the atmosphere of HAT-P-12b: solving discrepant results

Hubble PanCET: an extended upper atmosphere of neutral hydrogen around the warm Neptune GJ 3470b

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