Collisional broadening of the calcium infrared triplet lines by atomic hydrogen

The profiles of the calcium infrared triplet lines in light emitted at the center of the solar disk and in light emitted near the solar limb have been analyzed in order to determine the broadening parameters arising from collisions between calcium ions and hydrogen atoms. The analysis is based on high quality recordings of the spectral region 8000-9000 A made using the Fourier Transform Spectrometer and McMath solar telescope of the National Solar Observatory on Kitt Peak. It appears that a single value of the broadening parameter can account for the wing profiles of all three lines at both disk positions. A small excess absorption attributable to the Paschen lines, P13 and P15, of hydrogen is found in the long wavelength wings of the disk center profiles of the 8662 and 8542 A lines.