Photometric properties of resolved and unresolved magnetic elements

¹ Osservatorio astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Italy e-mail: criscuoli@mporzio.astro.it
² Laboratory for Atmospheric and Space Physics, Department of Astrophysical and Planetary Science, University of Colorado, Boulder CO, 80309-0391 USA e-mail: mark.rast@lasp.colorado.edu

Received: 20 June 2008
Accepted: 16 December 2008

Abstract

Aims. We investigate the photometric signature of magnetic flux tubes in the solar photosphere.

Methods. We developed two-dimensional, static numerical models of isolated and clustered magnetic flux tubes. We investigated the emergent intensity profiles at different lines-of-sight for various spatial resolutions and opacity models.

Results. We found that both geometric and photometric properties of bright magnetic features are determined not only by the physical properties of the tube and its surroundings, but also by the particularities of the observations, including the line/continuum formation height, the spatial resolution, and the image analysis techniques applied. We show that some observational results presented in the literature can be interpreted by considering bright magnetic features to be clusters of smaller elements, rather than a monolithic flux tube.