Semi-empirical model of solar plages

By use of the 2-m McMath-Pierce telescope at Kitt Peak, the high-quality spectra of a moderate-brightness plage near the center of solar disk were obtained, The data include seven spectral lines: H alpha, H beta, Call H and K lines and infrared triplet. Under the assumption of plane-parallel atmosphere, the hydrostatic, transfer and statistic equilibrium equations were solved iteratively and the semi-empirical model of the plage has been obtained. It can well reproduce the observed seven line profiles. The model has been compared with two existing plage models. Further improvement has also been discussed.