Linelist files

A linelist file, suitable for use from 3000 - 6800Å for luke-warm stars (mid B to K-type stars) is available on the download webpage. This file, called luke.lst, contains data for over half a million atomic and molecular lines. The format of a typical line is as follows:

4045.813   26.0   11976   36686    0.280  1.000 01  NIST

The first entry is the wavelength of the spectral line in angstroms. The second is the species code, which gives both the atomic number and the ionization state. The code ``26.0'' refers to an Fe I (neutral iron) line, as the atomic number of iron is 26, and the neutral ionization state is given as decimal 0. The code for Fe II is 26.1, the code for Ca III is 20.2 and so on. For diatomic molecules, the code specifies the atomic makeup of the molecule. Thus, H$_2$ is 101.0, the two ``1''s referring to the two hydrogens, CH is 106.0, CO 608.0, MgH 112.0, TiO 822.0, etc. The lightest element always comes first in the code, so that 608.0 cannot be confused with NdO, which would be written 860.0. The third entry is the energy of the lower state in cm$^{-1}$, and the fourth, in the case of atomic species, the energy of the upper state. Since only the energy of the lower state is used in molecular calculations, this entry is sometimes used to encode the molecular band information. The fifth entry is the log(gf) value, that is the logarithm of the product of the statistical weight of the lower level and the oscillator strength for the transition. The sixth entry is a fudge factor which can be used to adjust the calculation for the van der Waals broadening of the line. The seventh entry encodes the type of transition; ``01'' refers to an s-p transition, ``12'' a p-d transition, etc. The default coding is ``99'' which is used when 1) the compiler of the linelist has been too lazy to determine the type of transition, 2) when the transition does not fit into these simple categories (for instance it may involve two electrons) or 3) for a molecular line. Three other possible codings for the seventh entry are ``AO'', ``GA'', and ``AI''. ``AO'' enables the user to provide SPECTRUM, in a packed format, the $\sigma$ and $\alpha$ parameters used in the Anstee and O'Mara broadening theory. ``GA'' can be used to input the individual broadening half-widths for natural broadening, Stark broadening and van der Waals broadening. These two options are discussed in more detail in §  below. ``AI'' can be used in the computation of autoionizing lines; see § . Finally, the eighth entry gives the source of the data. In the example above, ``NIST'' obviously stands for the National Institute of Standards and Technology, and their wonderful and very useful atomic line and level website, http://physics.nist.gov/PhysRefData/ASD/index.html. If the source begins with a ``K'', this means it comes from the Kurucz line lists which contain tens of millions of both atomic and molecular lines. Most of the data in luke.lst come from those sources. The Kurucz data may be picked up on his website (http://kurucz.harvard.edu).

More linelist files in the format required by SPECTRUM may be picked up from the SPECTRUM distribution site, and others are available on special request. For instance, luke.lst does not include lines of TiO or ZrO, but a file called cool5.lst which does is available.

If SPECTRUM is operated in the isotope mode, an additional column must be included in the linelist file. See the discussion in §  below.