Gravity and limb-darkening coefficients for theKepler, CoRoT,Spitzer,uvby,UBVRIJHK, and Sloan photometric systems

Abstract

Aims. The complex physics of close binary stars is made even more challenging by the proximity effects that affect it. Understanding the influence of these proximity effects is one of the most important tasks in theoretical stellar astrophysics. It is crucial to know how the specific intensity is distributed over the stellar disk for a correct modelling of the light curves of eclipsing binaries and planetary transits. To provide theoretical input for light curve modelling codes, we present new calculations of gravity-and limb-darkening coefficients for a wide range of effective temperatures, gravities, metallicities, and microturbulent velocities. Methods. We computed limb-darkening coefficients for several atmosphere models, which cover the transmission curves of the Kepler, CoRoT, and Spitzer space missions as well as more widely used passbands (Strömgren, Johnson-Cousins, Sloan). In addition to these computations, which were made adopting the least-square method, we also performed calculations for the bi-parametric approximations by adopting the flux conservation method to provide users with an additional tool to estimate the theoretical error bars. To facilitate the modelling of the effects of tidal and rotational distortions, we computed the gravity-darkening coefficients y(λ) using the same models of stellar atmospheres as for the limb-darkening. Compared to previous work, a more general differential equation was used, which now takes into account local gravity variations and the effects of convection. Results. The limb-darkening coefficients were computed with a higher numerical resolution (100 μ points instead of 15 or 17, as is often used in the ATLAS models), and five equations were used to describe the specific intensities (linear, quadratic, root-square, logarithmic, and a 4-coefficient law). Concerning the gravity-darkening coefficients, the influence of the local gravity on y(λ) is shown as well as the effects of convection, which turn out to be very significant for cool stars. The results are tabulated for log g s ranging from 0.0 to 5.0, -5.0 ≤ log [M/H] ≤ +1, 2000 K ≤ T eff ≤ 50 000 K and for five values of the microturbulent velocity. ATLAS and PHOENIX plane-parallel atmosphere models were used for all computations.

SECURE MASS MEASUREMENTS FROM TRANSIT TIMING: 10 KEPLER EXOPLANETS BETWEEN 3 AND 8 M ⊕ WITH DIVERSE DENSITIES AND INCIDENT FLUXES

“…We adopt the analytic model of Mandel & Agol (2002) for the transit profile, with quadratic limb-darkening parameters from Claret & Bloemen (2011). Atmospheric parameters come from the most recent version of the Kepler Input Catalog retrieval from the NASA Exoplanet Archive (Huber et al 2014).…”

Variability in the super-Earth 55 Cnc e

“…In a first MCMC run, we keep the eccentricity fixed to zero as previous studies using radial-velocity data, which provides better constraints on √ e sin ω, found eccentricity values consistent with 0 (Nelson et al 2014). We also add the limbdarkening linear combinations c1 = 2u1 + u2 and c2 = u1 − 2u2 as jump parameters, where u1 and u2 are the quadratic coefficients drawn from the theoretical tables of Claret & Bloemen (2011) using published stellar parameters (von Braun et al 2011). We impose Gaussian priors on the limb-darkening coefficients and the radial-velocity semi amplitude K (Nelson et al 2014).…”

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

“…The a/R * , e, ω, i, and P p of each of the planets are fixed to their values listed in Table 6. The linear and quadratic limb darkening coefficients in each filter are taken from Claret & Bloemen (2011) and interpolated to the stellar parameters of the host stars (see Table 7) using the EXOFAST applet 8 (Eastman et al 2013). In addition, a linear or quadratic least squares fit is modelled to the OoT baseline simultaneously with the Mandel & Agol (2002) model.…”