Can microlensing fold caustics reveal a second stellar limb-darkening coefficient?
arXiv:astro-ph/0403212 · doi:10.1111/j.1365-2966.2004.08019.x
Abstract
Dense high-precision photometry of microlensed stars during a fold-caustic passage can be used to reveal their intensity profiles from which the temperature of the stellar atmosphere as function of fractional radius can be derived. While the capabilities of current microlensing follow-up campaigns such as PLANET allow a precise measurement of linear limb-darkening coefficients, the residual signal of a second coefficient characterizing square-root limb darkening is ~ 25 times smaller which prevents a proper determination except for unlikely cases of very high caustic-peak-to-outside relative magnifications with no adequate event being observed so far or for source stars passing over a cusp singularity. Although the presence of limb darkening can be well established from the data, a reliable measurement of the index of an underlying power-law cannot be obtained.
4 pages with 4 EPS figures embedded, LaTeX2e using mn2e.cls. Final version, minor changes. This is a preprint of an Article accepted for publication in Monthly Notices of the Royal Astronomical Society, (C) 2004 The Royal Astronomical Society
References in corpus (3)
Cited by in corpus (6)
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- Limb Darkening and Planetary Transits: Testing Center-to-limb Intensity Variations and Limb-Darkening Directly from Model Stellar Atmospheres
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