High-Precision Limb-Darkening Measurement of a K3 Giant Using Microlensing

Fields, Dale; Albrow, M; An, J.; Beaulieu, J.-P; Caldwell, J A R; DePoy, D; Dominik, M; Gaudi, B S; Gould, A; Greenhill, J; Hill, Kym; Jorgensen, U G; Kane, S; Martin, R; Menzies, J; Pogge, R W; Pollard, K R; Sackett, Penny; Sahu, K C; Vermaak, P; Watson, R; Williams, Andrew; Glicenstein, J F; Hauschildt, Peter H

High-Precision Limb-Darkening Measurement of a K3 Giant Using Microlensing

Date

2003

Authors

Fields, Dale

Albrow, M

An, J.

Beaulieu, J.-P

Caldwell, J A R

DePoy, D

Dominik, M

Gaudi, B S

Gould, A

Greenhill, J

Publisher

IOP Publishing

Abstract

We obtain high-precision limb-darkening measurements in five bands (V, VE, IE, I, and H) for the K3 III (Teff = 4200 K, [Fe/H] = +0.3, log g = 2.3) source of the Galactic bulge microlensing event EROS BLG-2000-5. These measurements are inconsistent with the predictions of atmospheric models at higher than 10 σ. While the disagreement is present in all bands, it is most apparent in I, IE, and VE, in part because the data are better and in part because the intrinsic disagreement is stronger. We find that when limb-darkening profiles are normalized to have unit total flux, the I-band models for a broad range of temperatures all cross each other at a common point. The solar profile also passes through this point. However, the profile as measured by microlensing does not. We hypothesize that the models have incorporated some aspect of solar physics that is not shared by giant atmospheres.