Atomic and Molecular Species Supported

As mentioned in previous sections, SPECTRUM supports all 92 naturally occurring elements, including a total of 310 isotopes of those elements. The ionization states supported for those elements can be found in the atomic and molecular data file, stdatom.dat. The very last column of that file indicates, for a given element, the maximum charge state for which spectra can be computed. For instance, the maximum charge for iron (26) is 3, meaning that spectra can be computed for Fe I, Fe II, Fe III and Fe IV. The ionization states supported depend upon the availability of partition function data in the literature. To calculate accurate number densities for a given ionization state, partition function data for the next higher ion must be built into SPECTRUM.

Molecular species supported by SPECTRUM are also listed in stdatom.dat. Currently, only diatomic molecules are supported; those supported are H$_2$, CH, NH, OH, MgH, SiH, CaH, C$_2$, CN, CO, SiO and TiO. In v2.76, AlH, AlO, and ZrO were added. Other diatomic molecules will be added in the future, and can be added fairly easily on request, if partition function data are available. Molecules involving different isotopes are also supported. See §  above and §  below.

It should be noted that spectral lines for certain species are ``hard coded'' into SPECTRUM. This includes certain hydrogen-line series (Lyman, Balmer, Paschen, Brackett, Pfund and Humphreys), and lines of He I. He II lines are on the ``to do list'' to be coded into SPECTRUM. All of these lines require special calculations for Stark broadening and various other effects, such as forbidden components in the He I profiles. Certain other very strong lines, such as the Ca II K & H lines have also been hard-coded into SPECTRUM. You can see which lines are in this ``strong-line'' list by looking at the code for the function strong6.c. The point is that the hard-coded lines should not be included in the spectral linelist, or they will be computed twice and appear to either be unusually strong, or have a peculiar profile.