Synspec Level Checker

Methodology

This recipe explains how to check if the level of a spectral line is correct.

1. Synthesize the line. The parameters are not important. We just want to generate the output files.

2. In the file fort.12, look for the desired spectral line. To find it, you can use the third, fourth and fifth column that are, respectively, the central wavelength, the chemical element and the ionization stage.

   What we need is the number of the lower level (11th column) and the upper level (12th column).

   For example, let's identify the Si IV line at 4116.104 angstrons. The line on the fort.12 file refferring to this spectral line is:

   9 5584 4116.104 Si IV -0.11 193978.889 1.19E+00 56.8 ** 1394 1395 31

   The values that we want are 1394 and 1395.

3. For this step, it is needed a output from Tlusty with termination .6. Tlusty is, as advertised by the authors, "A user-oriented package for modeling stellar atmospheres and accretion disks and for stellar spectroscopic diagnostics". The levelchcker only works if you are using a grid of atmospheric models from Tlusty.

   Open the file .6 file and look for the section called EXPLICIT IONS INCLUDED. Here, it has all identification levels used by Synspec. Note that the lower level is for Hydrogen and the following ones will only stacking over one another. Thus, look for the chemical element and ionization stage desired and obtain the values of the lowest level (column N0).

   For our example, we have:

   27 Si 4 1390 1442 1443 4 0 16 0.000D+00

   And the needed value is in boldface.

4. Subtract the level indifications found on (2) and (3).

   For our little example, we have:

   lower level : 1394 - 1390 = 05

   upper level : 1395 - 1390 = 06

   Note that the lower level identification has to be included.

5. With the lower and upper level identified, open the file containing the atomic data for the chemical element and ionization stage desired. It should be in a folder called atdata. In this file, the level are in ascending order.

   If we go back to the example, we will look into the file atdata\Si4_53lev.dat and obtain the 13th and the 19th level:

   5.09978082E+15 2. 4 'SiIV 2Se 2' 0 0. -105

   4.36843030E+15 6. 4 'SiIV 2Po 2' 0 0. -105

   And the levels are showed in boldface, i.e., the lower level is Si IV 2Se 2 and the upper level is SiIV 2Po 2. The last term ('2') means that it is the the second level with this term ('2 Se' for the lower level and '2Po' for the upper term).

6. Go to NIST or look for a table of eletronic transitions and check if the wavelength of the desired line is correct.

   The NIST pages to go are the Lines Form and the Levels Form.

   On the Lines Form fill the chemical element plus ionization stage and the wavelength range and then press retrieve. For our example, we can see that the lower level is 2p6.4s 2S and the upper level is 2p6.4p 2P*, where * means 'odd'.

   On the Levels Form, fill the chemical element and ionization stage and retrieve the data. For the lower level we had obtained 2Se 2, which is the second configuration with the term 2Se and we see from the Levels Formt table that it is 2p6.45 2S, in accordance with what we got on the Lines Form. The same line of thinking can be made for the upper level. Thus, we can see that both levels are correct.