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Paper: The Influence of Molecular Lines on the Measurement of Photospheric Velocities
Volume: 463, 2nd ATST-EAST Workshop in Solar Physics: Magnetic Fields from the Photosphere to the Corona
Page: 99
Authors: Uitenbroek, H.; Dumont, N.; Tritschler, A.
Abstract: We use different solar atmospheric models to investigate the influence of molecular lines on the accuracy with which line-of-sight velocities of mass flows can be measured from Doppler shifts. Particularly in relatively cool atmospheres molecules become more abundant and give rise to a thick forest of perturbing lines. Using bisectors we estimate the apparent shift introduced in the positions of the C I 538.0 nm and Fe I 557.6 nm lines by molecular lines in one-dimensional models with different effective temperatures, ranging from 3750 K to 6250 K, and in a three-dimensional section from a solar magneto-convection simulation. We find that the core of the iron line is mostly unaffected, and that by contrast the carbon line is severely compromised by molecular lines, even in environments with effective temperatures similar to those in the quiet Sun.
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