Name/Affiliation: Luca Bertello, Alexei A. Pevtsov, Mark S. Giampapa, Andrew R. Marble (National Solar Observatory)
Solar cycle Dependency of Sun-as-a-Star Photospheric Spectral Line Profiles
We investigate solar-cycle related changes in the profile of several photospheric spectral lines taken with the Integrated Sunlight Spectrometer (ISS) operating at the National Solar Observatory at Kitt Peak (Arizona). Daily high spectral resolution (R = 300,000) measurements of the Sun-as-a-star were obtained since December 2006, covering the decline of solar cycle 23 and the rising phase of cycle 24. We present time series of line parameters (including core intensity, full width at half maximum, and equivalent width) and discuss their correlation to indices of solar magnetic activity. Because of their different response to variations in the thermodynamic and magnetic structures of the solar atmosphere, the measured line shape parameters provide an excellent tool for disentangling thermal and magnetic effects occurring during different phases of the solar cycle. The results of this analysis may also help with developing a better understanding of magnetic cycle of activity in other solar-like stars.