ldtk: Limb Darkening Toolkit

Parviainen, H.; Aigrain, S.

doi:10.1093/mnras/stv1857

Cited by 245 publications

(193 citation statements)

References 27 publications

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“…Different from previous EBOP-based models, this implementation uses the analytic method of Mandel & Agol (2002) for the quadratic limb-darkening law. GP-EBOP utilizes the LDtk toolkit (Parviainen & Aigrain 2015), which allows uncertainties in the stellar parameters (effective temperature, surface gravity, and metallicity) to be propagated through the PHOENIX stellar atmosphere models (Husser et al 2013) and into priors on the limbdarkening coefficients. Limb-darkening parameterization within the fitting process follows the triangular sampling method of Kipping (2013).…”

Section: Gp-ebopmentioning

confidence: 99%

New Low-mass Eclipsing Binary Systems in Praesepe Discovered by K2

Gillen

Hillenbrand

David

et al. 2017

ApJ

106

112

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We present the discovery and characterization of four low-mass ( < M 0.6  M ) eclipsing binary (EB) systems in the sub-Gyr old Praesepe open cluster using Kepler/K2 time series photometry and Keck/HIRES spectroscopy. We present a new Gaussian process EB model, GP-EBOP, as well as a method of simultaneously determining effective temperatures and distances for EBs. Three of the reported systems (AD 3814, AD 2615 and AD 1508) are detached and double-lined, and precise solutions are presented for the first two. We determine masses and radii to 1%-3% precision for AD 3814 and to 5%-6% for AD 2615. Together with effective temperatures determined to ∼50 K precision, we test the PARSEC v1.2 and BHAC15 stellar evolution models. Our EB parameters are more consistent with the PARSEC models, primarily because the BHAC15 temperature scale is hotter than our data over the mid-M-dwarf mass range probed. Both ADs 3814 and 2615, which have orbital periods of 6.0 and 11.6 days, are circularized but not synchronized. This suggests that either synchronization proceeds more slowly in fully convective stars than the theory of equilibrium tides predicts, or magnetic braking is currently playing a more important role than tidal forces in the spin evolution of these binaries. The fourth system (AD 3116) comprises a brown dwarf transiting a mid-M-dwarf, which is the first such system discovered in a sub-Gyr open cluster. Finally, these new discoveries increase the number of characterized EBs in sub-Gyr open clusters by 20% (40%) below < M 1.5 M e ( < M 0.6 M e ).

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Section: Gp-ebopmentioning

confidence: 99%

New Low-mass Eclipsing Binary Systems in Praesepe Discovered by K2

Gillen

Hillenbrand

David

et al. 2017

ApJ

106

112

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“…Instead, we run a Levenberg-Marquardt minimization on each planet candidate to fit a Mandel & Agol (2002) transit model. The stellar limbdarkening parameters are fixed to values derived using the PyLDTk package 25 (Parviainen & Aigrain 2015) and stellar parameters derived in Section 4.1. We find that this fit gives us a more reliable estimate of the transit ephemerides than TERRA.…”

Section: Triage and Vettingmentioning

confidence: 99%

Planetary Candidates from K2 Campaign 16

Crossfield

Schlieder

et al. 2018

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Given that Campaign 16 of the K2 mission is one of just two K2 campaigns observed so far in "forward-facing" mode, which enables immediate follow-up observations from the ground, we present a catalog of interesting targets identified through photometry alone. Our catalog includes 30 high-quality planet candidates (showing no signs of being non-planetary in nature), 48 more ambiguous events that may be either planets or false positives, 164 eclipsing binaries, and 231 other regularly periodic variable sources. We have released light curves for all targets in C16 and have also released system parameters and transit vetting plots for all interesting candidates identified in this paper. Of particular interest is a candidate planet orbiting the bright F dwarf HD73344 (V=6.9, K=5.6) with an orbital period of 15 days. If confirmed, this object would correspond to a 2.56±0.18 R ⊕ planet and would likely be a favorable target for radial velocity characterization. This paper is intended as a rapid release of planet candidates, eclipsing binaries, and other interesting periodic variables to maximize the scientific yield of this campaign, and as a test run for the upcoming TESS mission, whose frequent data releases call for similarly rapid candidate identification and efficient follow up.

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“…The transit model uses the quadratic limb darkening formalism by Mandel & Agol (2002), and is calculated using PyTransit (Parviainen & Aigrain 2015). PyTransit contains optimisations to compute a transit in multiple passbands with only a minor additional computational cost to the computation of a single passband transit, which reduces the computational burden due to the joint modelling approach.…”

Section: Overviewmentioning

confidence: 99%

The GTC exoplanet transit spectroscopy survey

Parviainen

Pallé

Chen

et al. 2018

A&A

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Aims. We set out to study the atmosphere of WASP-80b, a warm inflated gas giant with an equilibrium temperature of ∼800 K, using ground-based transmission spectroscopy covering the spectral range from 520 to 910 nm. The observations allow us to probe the existence and abundance of K and Na in WASP-80b's atmosphere, existence of high-altitude clouds, and Rayleigh-scattering in the blue end of the spectrum. Methods. We observed two spectroscopic time series of WASP-80b transits with the OSIRIS spectrograph installed in the Gran Telescopio CANARIAS, and use the observations to estimate the planet's transmission spectrum between 520 nm and 910 nm in 20 nm-wide passbands, and around the K I and Na I resonance doublets in 6 nm-wide passbands. We model three previously published broadband datasets consisting of 27 light curves jointly prior to the transmission spectroscopy analysis in order to obtain improved prior estimates for the planet's orbital parameters, average radius ratio, and stellar density. The parameter posteriors from the broadband analysis are used to set informative priors on the transmission spectroscopy analysis. The final transmission spectroscopy analyses are carried out jointly for the two nights using a divide-by-white approach to remove the common-mode systematics and Gaussian processes to model the residual wavelength-dependent systematics. Results. We recover a flat transmission spectrum with no evidence of Rayleigh scattering or K I or Na I absorption, and obtain an improved system characterisation as a by-product of the broadband-and GTC-dataset modelling. The transmission spectra estimated separately from the two observing runs are consistent with each other, as are the transmission spectra estimated using either a parametric or nonparametric systematics models. The flat transmission spectrum favours an atmosphere model with high-altitude clouds over cloud-free models with stellar or sub-stellar metallicities. Conclusions. Our results disagree with the recently published discovery of strong K I absorption in WASP-80b's atmosphere based on ground-based transmission spectroscopy with FORS2 at VLT.

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ldtk: Limb Darkening Toolkit

Cited by 245 publications

References 27 publications

New Low-mass Eclipsing Binary Systems in Praesepe Discovered by K2

New Low-mass Eclipsing Binary Systems in Praesepe Discovered by K2

Planetary Candidates from K2 Campaign 16

The GTC exoplanet transit spectroscopy survey

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