Radiative properties of magnetic elements
I. Why are -band bright points bright?
Kiepenheuer-Institut für Sonnenphysik, Schöneckstrasse 6, 79104 Freiburg, Germany
2 The University of Georgia, Dept. of Physics & Astronomy, Athens, GA 30602-2451, Greece
Corresponding author: O. Steiner, email@example.com
Accepted: 11 April 2001
Photospheric magnetic elements are most conspicuously visible in high-resolution G-band filtergrams. We show that their enhanced contrast in the G-band is due to a reduction of the CH abundance by dissociation in the deep photospheric layers of the flux tube, where it is hotter than in the surrounding atmosphere. As a consequence, the CH-lines weaken, allowing more of the continuum to "shine" through the forest of G-band CH-lines. We suggest that other molecular bands or atomic lines may exhibit a similar behaviour.
Key words: Sun: photosphere / Sun: magnetic fields / Sun: faculae, plages / solar irradiance variability / G-band
© ESO, 2001