| Issue |
A&A
Volume 372, Number 1, June II 2001
|
|
|---|---|---|
| Page(s) | L13 - L16 | |
| Section | Letters | |
| DOI | https://doi.org/10.1051/0004-6361:20010540 | |
| Published online | 15 June 2001 | |
Radiative properties of magnetic elements
I. Why are 
-band bright points bright?
1
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, steiner@kis.uni-freiburg.de
Received:
1
February
2001
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
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