Synthetic spectrum study of the sun and Arcturus

An LTE synthetic spectrum study of six 1-3 Angstrom wide intervals of the solar spectrum was conducted with the purpose of determining the microturbulent and macroturbulent velocities that best characterize the line forming region. Seventy-eight weak and moderate strength lines arising from 13 atoms and ions are included in the synthetic spectrum study. In addition, line profile calculations were performed for 58 weakly blended iron and titanium lines. Synthetic spectra were computed for the same intervals in Arcturus' spectrum. The purposes of this segment of the study were to determine the microturbulent and macroturbulent velocities and to determine the heavy element abundance. The microturbulent velocity can be satisfactorily represented by a constant value of 2.4 km/s throughout the line-forming region. Including a mild depth dependence in the deeper layers results in a small improvement in the agreement between the observed and computed spectra. The abundance results are based on the study of the 61 lines for which complete line data are available. The heavy elements are found to be underabundant as compared to the sun; the values of N (Arcturus)/N (sun) range from approx. 1/4 to approx. 1/2