Discovery and characterisation of long-period eclipsing binary stars from <i>Kepler</i> K2 campaigns 1, 2, and 3

Maxted, P. F. L.; Hutcheon, R. J.

doi:10.1051/0004-6361/201732463

Cited by 28 publications

(45 citation statements)

References 64 publications

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“…It should be noted that the LDC error estimates from ldtk are very small and have often had to be inflated in literature during fitting to account for systematic errors in the atmospheric models (e.g. Raynard et al 2018;Maxted & Hutcheon 2018). Alternatively, the power-2 limb darkening law has been recommended for the analysis of transit light curves as it has been shown to provide remarkable agreement between stellar atmospheric models and observations, particularly for cool stars (Morello et al 2017;Maxted 2018).…”

Section: Discussionmentioning

confidence: 99%

Detectability of shape deformation in short-period exoplanets

Akinsanmi

Barros

Santos

et al. 2019

A&A

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Context. Short-period planets suffer from extreme tidal forces from their parent stars. These forces deform the planets causing them to attain non-spherical shapes. The non-spherical shapes, modeled here as triaxial ellipsoids, can have an impact on the observed transit light-curves and the parameters derived for these planets. Aims. We investigate the detectability of tidal deformation in short-period planets from their transit light curves and the instrumental precision needed. We also aim to show how detecting planet deformation allows us to obtain an observational estimate of the second fluid Love number from the light curve which gives valuable information about the planet's internal structure. Methods. We adopted a model to calculate the shape of a planet due to the external potentials acting on it and used this model to modify the ellc transit tool. We used the modified ellc to generate the transit light curve for a deformed planet. Our model is parameterized by the Love number, hence for a given light curve we can derive the value of the Love number that best matches the observations. Results. We simulated the known cases of WASP-103b and WASP-121b which are expected to be highly deformed. Our analyses showed that instrumental precision ≤ 50 ppm/min is required to reliably estimate the Love number and detect tidal deformation. This precision can be achieved for WASP-103b in ∼40 transits using the Hubble Space Telescope and in ∼300 transits using the forthcoming CHEOPS instrument. However, fewer transits will be required for short-period planets that may be found around bright stars in the TESS and PLATO survey missions. The unprecedented precisions expected from PLATO and JWST can permit the detection of shape deformation with a single transit observation. However, the effects of instrumental and astrophysical noise must be well-considered as they can increase the number of transits required to reach the 50 ppm/min detection limit. We also show that improper modeling of limb darkening can act to bury signals related to shape of the planet thereby leading us to infer sphericity for a deformed planet. Therefore accurate determination of the limb darkening coefficients is required to confirm planet deformation.

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Section: Discussionmentioning

confidence: 99%

Detectability of shape deformation in short-period exoplanets

Akinsanmi

Barros

Santos

et al. 2019

A&A

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“…. Because of the large TESS pixels and the possibility the extracted flux was contaminated by neighbouring bright stars, we also included a third light component ( 3 ) in the TESS light curve model (seeMaxted & Hutcheon 2018) 3 . For efficiency, we evaluated the full light curve model at every fifth point in the LCOGT time-series, making use of ELLC's ability to linearly interpolate the model at intermediate times.…”

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THOR 42: A touchstone ∼24 Myr-old eclipsing binary spanning the fully-convective boundary

Murphy

Lawson

Onken

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present the characterization of CRTS J055255.7−004426 (=THOR 42), a young eclipsing binary comprising two pre-main sequence M dwarfs (combined spectral type M3.5). This nearby (103 pc), short-period (0.859 d) system was recently proposed as a member of the ∼24 Myr-old 32 Orionis Moving Group. Using ground-and space-based photometry in combination with medium-and high-resolution spectroscopy, we model the light and radial velocity curves to derive precise system parameters. The resulting component masses and radii are 0.497 ± 0.005 and 0.205 ± 0.002 M , and 0.659 ± 0.003 and 0.424 ± 0.002 R , respectively. With mass and radius uncertainties of ∼1 per cent and ∼0.5 per cent, respectively, THOR 42 is one of the most precisely characterized pre-main sequence eclipsing binaries known. Its systemic velocity, parallax, proper motion, colour-magnitude diagram placement and enlarged radii are all consistent with membership in the 32 Ori Group. The system provides a unique opportunity to test pre-main sequence evolutionary models at an age and mass range not well constrained by observation. From the radius and mass measurements we derive ages of 22-26 Myr using standard (non-magnetic) models, in excellent agreement with the age of the group. However, none of the models can simultaneously reproduce the observed mass, radius, temperature and luminosity of the coeval components. In particular, their H-R diagram ages are 2-4 times younger and we infer masses ∼50 per cent smaller than the dynamical values.

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“…From the results in Table 6, we see that a constraint on E(B-V) of about 0.01 mag is needed to reduce T eff errors to less than 50 K. Uncertain reddening will tend to bias the T eff estimates as E(B-V) cannot be negative. There are many bright eclipsing binaries of all types being discovered as a results of survey like WASP, KELT, K2, TESS, ASAS (Kirkby-Kent et al 2018;Lubin et al 2017;Maxted & Hutcheon 2018;Lee et al 2019;He lminiak et al 2019b), many of which have both Gaia parallaxes and a wealth of archival photometry. We conclude that the prospects for measuring accurate and precise effective temperatures for a large number of stars in eclipsing binaries are excellent.…”

Section: Discussionmentioning

confidence: 99%

Fundamental effective temperature measurements for eclipsing binary stars – I. Development of the method and application to AI Phoenicis

Miller

Maxted

Smalley

2020

Monthly Notices of the Royal Astronomical Society

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Stars with accurate and precise effective temperature (Teff) measurements are needed to test stellar atmosphere models and calibrate empirical methods to determine Teff. There are few standard stars currently available to calibrate temperature indicators for dwarf stars. Gaia parallaxes now make it possible, in principle, to measure Teff for many dwarf stars in eclipsing binaries. We aim to develop a method that uses high-precision measurements of detached eclipsing binary stars, Gaia parallaxes and multi-wavelength photometry to obtain accurate and precise fundamental effective temperatures that can be used to establish a set of benchmark stars. We select the well-studied binary AI Phoenicis to test our method, since it has very precise absolute parameters and extensive archival photometry. The method uses the stellar radii and parallax for stars in eclipsing binaries. We use a Bayesian approach to obtain the integrated bolometric fluxes for the two stars from observed magnitudes, colours and flux ratios. The fundamental effective temperature of two stars in AI Phoenicis are 6199 ± 22 K for the F7 V component and 5094 ± 16 K for the K0 IV component. The zero-point error in the flux scale leads to a systematic error of only 0.2% (≈ 11 K) in Teff. We find that these results are robust against the details of the analysis, such as the choice of model spectra. Our method can be applied to eclipsing binary stars with radius, parallax and photometric measurements across a range of wavelengths. Stars with fundamental effective temperatures determined with this method can be used as benchmarks in future surveys.

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Discovery and characterisation of long-period eclipsing binary stars from Kepler K2 campaigns 1, 2, and 3

Cited by 28 publications

References 64 publications

Detectability of shape deformation in short-period exoplanets

Detectability of shape deformation in short-period exoplanets

THOR 42: A touchstone ∼24 Myr-old eclipsing binary spanning the fully-convective boundary

Fundamental effective temperature measurements for eclipsing binary stars – I. Development of the method and application to AI Phoenicis

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