High resolution magnetogram measurements of solar faculae

We present new images of magnetic elements near the solar limb ("faculae") along with magnetogram measurements and contrast profiles. Imaging magnetogram observations were made of AR 10377 at μ = cosθ = 0.6 on 06-June-2003 using the Swedish 1-m Solar Telescope; the data are the highest spatial resolution magnetogram measurements of faculae to date. Contrary to previous lower resolution measurements, we find no correlation between facular contrast and magnetic flux density at a given disk position. Increasing magnetic flux density in a region implies an increasing prevalence of micropores. Previous observations which lacked sufficient spatial resolution to discern dark micropore "floors" from bright facular walls find a strong non-linear dependence of facular contrast on magnetic flux density, with decreasing contrast beyond a certain flux density. We show instead that the observed contrast of bright facular walls is independent of magnetic flux density when properly segmented from dark micropores. The observations are useful for examining the detailed structure of faculae including the dark lanes found on the disk-center side of many faculae (explained by several recent 3D MHD numerical simulations). The average radial profile for 678 faculae segmented from the dataset is very nearly gaussian with a FWHM radial extent of 265 km and an extended tail on the limbward side, as predicted by current MHD simulations.