Carbon I, Solar Activity and Secular Change?

Authors: Peter Fox and Dick White
Affiliation: High Altitude Observatory, NCAR, Boulder, Colorado

We present solar spectral synthesis of the solar spectral line of Carbon I line at 538.03368 nm and the behavior of the adjacent lines of Fe I at 537.95741 nm, and Ti II at 538.10151 nm.

We compare observed spectral line profiles with those obtained by synthesis under realistic solar conditions, including a discussion of line equivalent widths, line depths and line depth ratios with the nearby lines.

We find that C I is very insensitive to surface solar activity over much of the solar disk, and only displaying some line strength variation near the limb. We also discuss the impact of this insensitivity in interpreting the existing observed time series and speculate on implications for Carbon I in assessing long-term solar variability.

This work is supported in part by grants from NASA and NSF. NCAR is sponsored by the National Science Foundation.