The TRAPPIST survey of southern transiting planets

Gillon, M.; Jehin, Emmanuël; Lendl, M.; Magain, Pierre; Kabáth, P.; Queloz, D.; Anderson, D. R.; Cameron, A. Collier; Hellier, C.; Lanotte, Audrey; Maxted, P. F. L.; Smalley, B.

doi:10.1051/0004-6361/201218817

Cited by 204 publications

(280 citation statements)

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“…1, the upper solid lines corresponding to the upper observed boundary of the planetary mass, the lower dashed lines corresponding to the lower observed boundary of the planetary mass. From these calculations, we infer that the volatile fraction of 55 Cnc e lies between 19% and 56%, consistant with previous evaluations (see, e.g., Gillon et al 2012). Interestingly enough, the recent determination of 55 Cnc e radius in Demory et al (2015) is much lower.…”

Section: Volatile Content Of Gas-poor Planetssupporting

confidence: 90%

“…We illustrated this method on the example of 55 Cnc e, showing that if gas is absent from the planet, its possible volatile content ranges from 20% to 50%, using the radius determination of Gillon et al (2012). This method is only applicable for very hot planets, however, and relies on the assumption that the entire planetary gas envelope has been lost through evaporation.…”

Section: Discussionmentioning

confidence: 99%

“…To illustrate this, we considered the close-in planet 55 Cnc e. We took the parameters of this planet (mass, period, and equilibrium temperature) from Gillon et al (2012) and used the abundances quoted in Bond et al (2010) for the 55 Cnc system. These parameters are summarized in Table 3.…”

Section: Volatile Content Of Gas-poor Planetsmentioning

confidence: 99%

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Constraining the volatile fraction of planets from transit observations

Alibert

2016

A&A

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Context. The determination of the abundance of volatiles in extrasolar planets is very important as it can provide constraints on transport in protoplanetary disks and on the formation location of planets. However, constraining the internal structure of low-mass planets from transit measurements is known to be a degenerate problem. Aims. Using planetary structure and evolution models, we show how observations of transiting planets can be used to constrain their internal composition, in particular the amount of volatiles in the planetary interior, and consequently the amount of gas (defined in this paper to be only H and He) that the planet harbors. We first explore planets that are located close enough to their star to have lost their gas envelope. We then concentrate on planets at larger distances and show that the observation of transiting planets at different evolutionary ages can provide statistical information on their internal composition, in particular on their volatile fraction. Methods. We computed the evolution of low-mass planets (super-Earths to Neptune-like) for different fractions of volatiles and gas. We used a four-layer model (core, silicate mantle, icy mantle, and gas envelope) and computed the internal structure of planets for different luminosities. With this internal structure model, we computed the internal and gravitational energy of planets, which was then used to derive the time evolution of the planet. Since the total energy of a planet depends on its heat capacity and density distribution and therefore on its composition, planets with different ice fractions have different evolution tracks. Results. We show for low-mass gas-poor planets that are located close to their central star that assuming evaporation has efficiently removed the entire gas envelope, it is possible to constrain the volatile fraction of close-in transiting planets. We illustrate this method on the example of 55 Cnc e and show that under the assumption of the absence of gas, the measured mass and radius imply at least 20% of volatiles in the interior. For planets at larger distances, we show that the observation of transiting planets at different evolutionary ages can be used to set statistical constraints on the volatile content of planets. Conclusions. These results can be used in the context of future missions like PLATO to better understand the internal composition of planets, and based on this, their formation process and potential habitability.

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Section: Volatile Content Of Gas-poor Planetssupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

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Constraining the volatile fraction of planets from transit observations

Alibert

2016

A&A

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“…An exhaustive description of the MCMC adaptive algorithm applied in this study can be found in Gillon et al (2010Gillon et al ( , 2012. We use a model based on a star and a transiting planet on a Keplerian orbit about their centre of mass.…”

Section: Data and Modelmentioning

confidence: 99%

A global analysis ofSpitzerand new HARPS data confirms the loneliness and metal-richness of GJ 436 b

Lanotte

Gillon

Demory

et al. 2014

A&A

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Context. GJ 436b is one of the few transiting warm Neptunes for which a detailed characterisation of the atmosphere is possible, whereas its non-negligible orbital eccentricity calls for further investigation. Independent analyses of several individual datasets obtained with Spitzer have led to contradicting results attributed to the different techniques used to treat the instrumental effects. Aims. We aim at investigating these previous controversial results and developing our knowledge of the system based on the full Spitzer photometry dataset combined with new Doppler measurements obtained with the HARPS spectrograph. We also want to search for additional planets. Methods. We optimise aperture photometry techniques and the photometric deconvolution algorithm DECPHOT to improve the data reduction of the Spitzer photometry spanning wavelengths from 3-24 µm. Adding the high-precision HARPS radial velocity data, we undertake a Bayesian global analysis of the system considering both instrumental and stellar effects on the flux variation.Results. We present a refined radius estimate of R P = 4.10 ± 0.16 R ⊕ , mass M P = 25.4 ± 2.1 M ⊕ , and eccentricity e = 0.162 ± 0.004 for GJ 436b. Our measured transit depths remain constant in time and wavelength, in disagreement with the results of previous studies. In addition, we find that the post-occultation flare-like structure at 3.6 µm that led to divergent results on the occultation depth measurement is spurious. We obtain occultation depths at 3.6, 5.8, and 8.0 µm that are shallower than in previous works, in particular at 3.6 µm. However, these depths still appear consistent with a metal-rich atmosphere depleted in methane and enhanced in CO/CO 2 , although perhaps less than previously thought. We could not detect a significant orbital modulation in the 8 µm phase curve. We find no evidence of a potential planetary companion, stellar activity, or a stellar spin-orbit misalignment. Conclusions. Recent theoretical models invoking high-metallicity atmospheres for warm Neptunes are a reasonable match to our results, but we encourage new modelling efforts based on our revised data. Future observations covering a wide wavelength range of GJ 436b and other Neptune-class exoplanets will further illuminate their atmosphere properties, whilst future accurate radial velocity measurements might explain the eccentricity.

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“…We employed the MCMC method using the implementation described in Gillon et al (2010Gillon et al ( , 2012. In short, the radial velocities are modeled using a Keplerian orbit and with the prescription of the Rossiter-McLaughlin effect (Rossiter 1924;McLaughlin 1924) provided by Giménez (2006).…”

Section: Mcmcmentioning

confidence: 99%

A photometric study of the hot exoplanet WASP-19b

Lendl

Gillon

Queloz

et al. 2013

A&A

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Context. The sample of hot Jupiters that have been studied in great detail is still growing. In particular, when the planet transits its host star, it is possible to measure the planetary radius and the planet mass (with radial velocity data). For the study of planetary atmospheres, it is essential to obtain transit and occultation measurements at multiple wavelengths. Aims. We aim to characterize the transiting hot Jupiter WASP-19b by deriving accurate and precise planetary parameters from a dedicated observing campaign of transits and occultations. Methods. We have obtained a total of 14 transit lightcurves in the r -Gunn, I-Cousins, z -Gunn, and I + z filters and 10 occultation lightcurves in z -Gunn using EulerCam on the Euler-Swiss telescope and TRAPPIST. We also obtained one lightcurve through the narrow-band NB1190 filter of HAWK-I on the VLT measuring an occultation at 1.19 µm. We performed a global MCMC analysis of all new data, together with some archive data in order to refine the planetary parameters and to measure the occultation depths in z -band and at 1.19 µm. Results. We measure a planetary radius of R p = 1.376 ± 0.046 R J , a planetary mass of M p = 1.165 ± 0.068 M J , and find a very low eccentricity of e = 0.0077 +0.0068 −0.0032 , compatible with a circular orbit. We have detected the z -band occultation at 3σ significance and measure it to be δF occ,z = 352 ± 116 ppm, more than a factor of 2 smaller than previously published. The occultation at 1.19 µm is only marginally constrained at δF occ,NB1190 = 1711 +745 −726 ppm. Conclusions. We show that the detection of occultations in the visible range is within reach, even for 1 m class telescopes if a considerable number of individual events are observed. Our results suggest an oxygen-dominated atmosphere of WASP-19b, making the planet an interesting test case for oxygen-rich planets without temperature inversion.

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The TRAPPIST survey of southern transiting planets

Cited by 204 publications

References 53 publications

Constraining the volatile fraction of planets from transit observations

Constraining the volatile fraction of planets from transit observations

A global analysis ofSpitzerand new HARPS data confirms the loneliness and metal-richness of GJ 436 b

A photometric study of the hot exoplanet WASP-19b

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